├── samples
    ├── demo-qa-issues.yar
    ├── demo2.yar
    ├── demo-broken.yar
    ├── demo-bad.yar
    ├── private-rule-example.yar
    ├── demo.yar
    ├── demo3.yar
    └── gen_webshells.yar
├── .gitignore
├── README.md
└── LICENSE


/samples/demo-qa-issues.yar:
--------------------------------------------------------------------------------
 1 | 
 2 | rule Demo_Rule_2_Short_Atom : APT {
 3 |    meta:
 4 |       description = "Rule that has a short atom"
 5 |       author = "Florian Roth"
 6 |       date = "2023-01-04"
 7 |       reference = "https://github.com/Neo23x0/yaraQA"
 8 |       score = 0
 9 |    strings:
10 |       $s1 = { 01 02 03 }
11 |    condition:
12 |       all of them
13 | }
14 | 


--------------------------------------------------------------------------------
/samples/demo2.yar:
--------------------------------------------------------------------------------
 1 | 
 2 | rule HKTL_EXPL_POC_LibSSH_Auth_Bypass_CVE_2023_2283_Jun23_1 {
 3 |    meta:
 4 |       myinf = "Detects POC code used in attacks against libssh vulnerability CVE-2023-2283"
 5 |       author = "Florian Roth"
 6 |       score = 85
 7 |       url = "https://www.test.de"
 8 |       date = "2023-10-01"
 9 |       id = "ccd8d370af123"
10 |    strings:
11 |       $s1 = "nprocs = %d" ascii fullword
12 |       $s2 = "fork failed: %s" ascii fullword
13 |    condition:
14 |       uint16(0) == 0x457f and all of them
15 | }
16 | 


--------------------------------------------------------------------------------
/samples/demo-broken.yar:
--------------------------------------------------------------------------------
 1 | rule Rule_With_Issue {
 2 |   meta:
 3 |     description = "This is a broken rule"
 4 |     author = "Florian Roth"
 5 |     date = "2023-11-07"
 6 |   strings:
 7 |     $a1 = "this is a test"
 8 |     $a2 = "another string for the test"
 9 |   condition:
10 |     3 of them
11 | }
12 | 
13 | rule Rule_With_Error {
14 |   meta:
15 |     description = "This is a broken rule"
16 |     author = "Florian Roth"
17 |     date = "2023-11-07"
18 |   strings:
19 |     $a1 = "this is a test"
20 |     $a2 = "another string for the test"
21 |   condition:
22 |     all of ($s*)
23 | }
24 | 


--------------------------------------------------------------------------------
/samples/demo-bad.yar:
--------------------------------------------------------------------------------
 1 | rule Linux_Trojan_Iroffer_53692410 {
 2 |     meta:
 3 |         author = "Elastic Security"
 4 |         id = "53692410-4213-4550-890e-4c62867937bc"
 5 |         fingerprint = "f070ee35ad42d9d30021cc2796cfd2859007201c638f98f42fdbec25c53194fb"
 6 |         creation_date = "2021-01-12"
 7 |         last_modified = "2021-09-16"
 8 |         threat_name = "Linux.Trojan.Iroffer"
 9 |         reference_sample = "e76508141970efb3e4709bcff83772da9b10169c599e13e58432257a7bb2defa"
10 |         severity = 100
11 |         arch_context = "x86"
12 |         scan_context = "file, memory"
13 |         license = "Elastic License v2"
14 |         os = "linux"
15 |     strings:
16 |         $a = { 69 6E 67 20 55 6E 6B 6E 6F 77 6E 20 4D 73 67 6C 6F 67 20 54 61 67 }
17 |     condition:
18 |         all of them
19 | }
20 | 
21 | 
22 | rule CISA_10478915_01 : trojan installs_other_components {
23 |    meta:
24 |       author = "CISA Code & Media Analysis"
25 |       incident = "10478915"
26 |       date = "2023-11-06"
27 |       last_modified = "20231108_1500"
28 |       actor = "n/a"
29 |       family = "n/a"
30 |       capabilities = "installs-other-components"
31 |       malware_Type = "trojan"
32 |       tool_type = "information-gathering"
33 |       description = "Detects trojan .bat samples"
34 |       sha256 = "98e79f95cf8de8ace88bf223421db5dce303b112152d66ffdf27ebdfcdf967e9"
35 |       id = "db351fe25ae9d5f2f"
36 |    strings:
37 |       $s1 = { 63 3a 5c 77 69 6e 64 6f 77 73 5c 74 61 73 6b 73 5c 7a 2e 74 78 74 }
38 |       $s2 = { 72 65 67 20 73 61 76 65 20 68 6b 6c 6d 5c 73 79 73 74 65 6d 20 63 3a 5c 77 69 6e 64 6f 77 73 5c 74 61 73 6b 73 5c 65 6d }
39 |       $s3 = { 6d 61 6b 65 63 61 62 20 63 3a 5c 75 73 65 72 73 5c 70 75 62 6c 69 63 5c 61 2e 70 6e 67 20 63 3a 5c 77 69 6e 64 6f 77 73 5c 74 61 73 6b 73 5c 61 2e 63 61 62 }
40 |    condition:
41 |       uint16(0) == 0x6540 and all of them
42 | }
43 | 


--------------------------------------------------------------------------------
/samples/private-rule-example.yar:
--------------------------------------------------------------------------------
 1 | private rule ELF
 2 | {
 3 | 	strings:
 4 | 		$h01 = { 7F 45 4C 46 (01|02) (01|02) 01 }
 5 | 	condition:
 6 | 		$h01 at 0
 7 | }
 8 | 
 9 | private rule EXE
10 | {
11 | 	condition:
12 | 		uint16(0) == 0x5A4D and uint32(uint32(0x3C)) == 0x00004550
13 | }
14 | 
15 | rule manjusaka_payload_encoded_hexstring
16 | {
17 | 	meta:
18 | 		author = "Avast Threat Intel Team"
19 | 		source = "https://github.com/avast/ioc"
20 | 	strings:
21 | 		// ELF v01 and v02
22 | 		$s01 = "1f8b08000000000000ff7cdd099c1ae5fd3ff031e620c6038d5aea493df18a24c688372626c1180d468d78d465b34b96357be0ee2612354ab5553caa68ad454d158f2a566b51ab454d2dde"
23 | 		// ELF v03 (dev)
24 | 		$s02 = "1f8b08000000000000ff94dd09982355d9fffd62d89a45880a181621804240c10888718328a8ed864144a3029d66ba67d2cc4c4fecee8180a85114f3284b4096b00d619380085111f3284a"
25 | 		// ELF v03
26 | 		$s03 = "1f8b08000000000000ff94dd0b982355b5fffde21eee011503a204440d201001317a148278890a1804348ad269667a260d3d33b1bb19820246bc10914bb80811618c80108f084110232204"
27 | 		// ELF v04
28 | 		$s04 = "1f8b08000000000000ff94dd07981bd5d9fffdb131208a41b4075123ba280101c6112d88d04468a22b01b25abc6b6bf17aadecae4140008540103582001110401483e8a28b2e4a4074d197"
29 | 		// MZ v01
30 | 		$s11 = "1f8b08000000000000ffecbd09784cd7ff077c26c924631977828958c284694d5092da12eb8448ce302108a248628ba82d65862025e924b8aeabdaeaa2abb6bfaebad74f83fe4804a1d5d6"
31 | 		// MZ v02
32 | 		$s12 = "1f8b08000000000000ffecbd097414c5faff5d9d7502849e400209201974c4441113371240c8842cd5d00361070502224bdc403203a82c8993d1146d2b7ac5e5ba5cdcb9aea85c36176612"
33 | 		// MZ v03 (dev)
34 | 		$s13 = "1f8b08000000000000ffecbd7b7854d5d928be7632496620710d4874522e9991ad4e94627641491425031378b7ae1150046a1168a1237ca2419801542e893b53b3d8eeafb4b5777b8eb5fd"
35 | 		// MZ v03
36 | 		$s14 = "1f8b08000000000000ffecbd7b7854d5d530be4f32496620710f9ae8a45c3223479d28d51c414934960c4c601ddd23a811a845a0858e50d120cc002a97c49369b3399e96b6dacb5bfb7dbe"
37 | 		// MZ v04
38 | 		$s15 = "1f8b08000000000000ffecbd79785445d6305eb7934e3a90e676846887451abc68c7b5e33293284b37e924a7e506a222a022c45119501c23744b1c194ce6764b2a97abcc88233a3aaee38a"
39 | 	condition:
40 | 		(EXE or ELF) and (
41 | 			any of ($s0*) and
42 | 			any of ($s1*)
43 | 		)
44 | }
45 | 


--------------------------------------------------------------------------------
/samples/demo.yar:
--------------------------------------------------------------------------------
 1 | import "pe"
 2 | 
 3 | rule LOG_F5_BIGIP_Exploitation_Artefacts_CVE_2021_22986_Mar21_1 : LOG {
 4 |    meta:
 5 |       description = "Detects forensic artefacts indicating successful exploitation of F5 BIG IP appliances as reported by NCCGroup"
 6 |       reference = "https://research.nccgroup.com/2021/03/18/rift-detection-capabilities-for-recent-f5-big-ip-big-iq-icontrol-rest-api-vulnerabilities-cve-2021-22986/"
 7 |       status = "experimental"
 8 |       my_bogus_date = "01.01.2020"
 9 |       id = "ab48d370af123"
10 |    strings:
11 |       $x1 = "\",\"method\":\"POST\",\"uri\":\"http://localhost:8100/mgmt/tm/util/bash\",\"status\":200," ascii
12 |       $x2 = "[com.f5.rest.app.RestServerServlet] X-F5-Auth-Token doesn't have value, so skipping" ascii
13 |    condition:
14 |       1 of them
15 | }
16 | 
17 | rule SUSP_ThemeBleed_Theme_Sep23 {
18 |     meta:
19 |         description = "Detects domain or IP placement in Windows theme files"
20 |         author = "@m_haggis, @nas_bench"
21 |         reference = "https://github.com/gabe-k/themebleed"
22 |         score = 75
23 |     strings:
24 |         $s1 = /Path=\\\\[0-9a-zA-Z\.-]{1,20}\\/
25 |         $s2 = "[VisualStyles]"
26 |         $s3 = "[Theme]"
27 | 
28 |     condition:
29 |         filesize < 1MB and all of them
30 | }
31 | 
32 | rule SUSP_Bad_Regex_Sep23 {
33 |     meta:
34 |         description = "Detects a bad regex"
35 |         author = "Noob"
36 |         reference = "https://github.com/gabe-k/themebleed"
37 |         score = 75
38 |     strings:
39 |         $sr1 = /[\w\-.]{1,3}@[\w\-.]{1,3}/
40 |     condition:
41 |         $sr1
42 | }
43 | 
44 | rule WinnieThePooh{
45 |     meta:
46 |         desc = "Detects a fictional malware named WinnieThePooh exploiting CVE-2021-1675"
47 |         author = "Florian's Evil Twin"
48 |         url = "https://en.wikipedia.org/wiki/Censorship_of_Winnie-the-Pooh_in_China"
49 |         created = "2021-06-29"
50 |         modified = "2023-12-13"
51 |         tags = "rat, arcom"
52 |     strings:
53 |         $x1 = "\\WinnieThePooh.pdb" ascii
54 |         $x2 = "\\pipe\\WinnieThePooh" ascii
55 | 
56 |         $s1 = "] dumping creds"
57 |         $s2 = "\\temp\\lsass.dmp"
58 |     condition:
59 |         uint16(0) == 0x5A4D
60 |         and filesize < 1MB
61 |         and (
62 |             1 of ($x*)
63 |             or 2 of them
64 |         )
65 |         and not pe.number_of_signatures > 0
66 | }
67 | 


--------------------------------------------------------------------------------
/samples/demo3.yar:
--------------------------------------------------------------------------------
 1 | rule win_cobalt_sleep_encrypt
 2 | {
 3 | 	meta:
 4 | 		author = "Matthew @ Embee_Research"
 5 | 		created = "2023/08/27"
 6 | 		info = "Detects Sleep Encryption Logic Found in Cobalt Strike Deployments"
 7 | 		sha_256 = "26b2f12906c3590c8272b80358867944fd86b9f2cc21ee6f76f023db812e5bb1"
 8 | 		sha_1 = "14b1a681fea9c0833f20ecc6ef231dfb7cc62a3d"
 9 | 	strings:
10 | 	
11 | 		/*
12 | 		Encryption Round 1 / Decrypt Code
13 | 		0000000000CCFD2E | 4E:8B0408                | mov r8,qword ptr ds:[rax+r9]           
14 | 		0000000000CCFD32 | B8 4FECC44E              | mov eax,4EC4EC4F                       
15 | 		0000000000CCFD37 | 41:F7E3                  | mul r11d                               
16 | 		0000000000CCFD3A | 41:8BC3                  | mov eax,r11d                           
17 | 		0000000000CCFD3D | C1EA 02                  | shr edx,2                              
18 | 		0000000000CCFD40 | 41:FFC3                  | inc r11d                               
19 | 		0000000000CCFD43 | 6BD2 0D                  | imul edx,edx,D                         
20 | 		0000000000CCFD46 | 2BC2                     | sub eax,edx                            
21 | 		0000000000CCFD48 | 8A4C18 18                | mov cl,byte ptr ds:[rax+rbx+18]        
22 | 		0000000000CCFD4C | 41:300C38                | xor byte ptr ds:[r8+rdi],cl            
23 | 		0000000000CCFD50 | 48:8B43 10               | mov rax,qword ptr ds:[rbx+10]          
24 | 		0000000000CCFD54 | 41:8BFB                  | mov edi,r11d                           
25 | 		0000000000CCFD57 | 4A:3B7C08 08             | cmp rdi,qword ptr ds:[rax+r9+8]        
26 | 				
27 | 		Encryption Round 2 / Possible Re-encrypt Code
28 | 		0000000000CCFD93 | 49:8BF9                  | mov rdi,r9                           
29 | 		0000000000CCFD96 | 4C:8B03                  | mov r8,qword ptr ds:[rbx]            
30 | 		0000000000CCFD99 | B8 4FECC44E              | mov eax,4EC4EC4F                     
31 | 		0000000000CCFD9E | 41:F7E1                  | mul r9d                              
32 | 		0000000000CCFDA1 | 41:8BC1                  | mov eax,r9d                          
33 | 		0000000000CCFDA4 | C1EA 02                  | shr edx,2                            
34 | 		0000000000CCFDA7 | 41:FFC1                  | inc r9d                              
35 | 		0000000000CCFDAA | 6BD2 0D                  | imul edx,edx,D                       
36 | 		0000000000CCFDAD | 2BC2                     | sub eax,edx                          
37 | 		0000000000CCFDAF | 8A4C18 18                | mov cl,byte ptr ds:[rax+rbx+18]      
38 | 		0000000000CCFDB3 | 42:300C07                | xor byte ptr ds:[rdi+r8],cl          
39 | 		0000000000CCFDB7 | 48:FFC7                  | inc rdi                              
40 | 		0000000000CCFDBA | 45:3BCB                  | cmp r9d,r11d                         
41 | 		
42 | 		*/
43 | 		
44 | 		
45 | 		$r1_nokey = {4E 8B 04 08 B8 ?? ?? ?? ?? 41 F7 E3 41 8B C3 C1 EA 02 41 FF C3 6B D2 0D 2B C2 8A 4C 18 18 41 30 0C 38 48 8B 43 10 41 8B FB 4A 3B 7C 08 08}
46 | 
47 | 		$r2_nokey = {49 8B F9 4C 8B 03 B8 ?? ?? ?? ?? 41 F7 E1 41 8B C1 C1 EA 02 41 FF C1 6B D2 0D 2B C2 8A 4C 18 18 42 30 0C 07 48 FF C7 45 3B CB}
48 | 		
49 | 	condition:
50 | 		//uint16(0) == 0x5a4d and
51 | 		//filesize < 3000KB and
52 | 		($r1_nokey or $r2_nokey)
53 | 		
54 | 
55 | }
56 | 


--------------------------------------------------------------------------------
/.gitignore:
--------------------------------------------------------------------------------
  1 | # Byte-compiled / optimized / DLL files
  2 | __pycache__/
  3 | *.py[cod]
  4 | *$py.class
  5 | 
  6 | # C extensions
  7 | *.so
  8 | 
  9 | # Distribution / packaging
 10 | .Python
 11 | build/
 12 | develop-eggs/
 13 | dist/
 14 | downloads/
 15 | eggs/
 16 | .eggs/
 17 | lib/
 18 | lib64/
 19 | parts/
 20 | sdist/
 21 | var/
 22 | wheels/
 23 | share/python-wheels/
 24 | *.egg-info/
 25 | .installed.cfg
 26 | *.egg
 27 | MANIFEST
 28 | 
 29 | # PyInstaller
 30 | #  Usually these files are written by a python script from a template
 31 | #  before PyInstaller builds the exe, so as to inject date/other infos into it.
 32 | *.manifest
 33 | *.spec
 34 | 
 35 | # Installer logs
 36 | pip-log.txt
 37 | pip-delete-this-directory.txt
 38 | 
 39 | # Unit test / coverage reports
 40 | htmlcov/
 41 | .tox/
 42 | .nox/
 43 | .coverage
 44 | .coverage.*
 45 | .cache
 46 | nosetests.xml
 47 | coverage.xml
 48 | *.cover
 49 | *.py,cover
 50 | .hypothesis/
 51 | .pytest_cache/
 52 | cover/
 53 | 
 54 | # Translations
 55 | *.mo
 56 | *.pot
 57 | 
 58 | # Django stuff:
 59 | *.log
 60 | local_settings.py
 61 | db.sqlite3
 62 | db.sqlite3-journal
 63 | 
 64 | # Flask stuff:
 65 | instance/
 66 | .webassets-cache
 67 | 
 68 | # Scrapy stuff:
 69 | .scrapy
 70 | 
 71 | # Sphinx documentation
 72 | docs/_build/
 73 | 
 74 | # PyBuilder
 75 | .pybuilder/
 76 | target/
 77 | 
 78 | # Jupyter Notebook
 79 | .ipynb_checkpoints
 80 | 
 81 | # IPython
 82 | profile_default/
 83 | ipython_config.py
 84 | 
 85 | # pyenv
 86 | #   For a library or package, you might want to ignore these files since the code is
 87 | #   intended to run in multiple environments; otherwise, check them in:
 88 | # .python-version
 89 | 
 90 | # pipenv
 91 | #   According to pypa/pipenv#598, it is recommended to include Pipfile.lock in version control.
 92 | #   However, in case of collaboration, if having platform-specific dependencies or dependencies
 93 | #   having no cross-platform support, pipenv may install dependencies that don't work, or not
 94 | #   install all needed dependencies.
 95 | #Pipfile.lock
 96 | 
 97 | # poetry
 98 | #   Similar to Pipfile.lock, it is generally recommended to include poetry.lock in version control.
 99 | #   This is especially recommended for binary packages to ensure reproducibility, and is more
100 | #   commonly ignored for libraries.
101 | #   https://python-poetry.org/docs/basic-usage/#commit-your-poetrylock-file-to-version-control
102 | #poetry.lock
103 | 
104 | # pdm
105 | #   Similar to Pipfile.lock, it is generally recommended to include pdm.lock in version control.
106 | #pdm.lock
107 | #   pdm stores project-wide configurations in .pdm.toml, but it is recommended to not include it
108 | #   in version control.
109 | #   https://pdm.fming.dev/#use-with-ide
110 | .pdm.toml
111 | 
112 | # PEP 582; used by e.g. github.com/David-OConnor/pyflow and github.com/pdm-project/pdm
113 | __pypackages__/
114 | 
115 | # Celery stuff
116 | celerybeat-schedule
117 | celerybeat.pid
118 | 
119 | # SageMath parsed files
120 | *.sage.py
121 | 
122 | # Environments
123 | .env
124 | .venv
125 | env/
126 | venv/
127 | ENV/
128 | env.bak/
129 | venv.bak/
130 | 
131 | # Spyder project settings
132 | .spyderproject
133 | .spyproject
134 | 
135 | # Rope project settings
136 | .ropeproject
137 | 
138 | # mkdocs documentation
139 | /site
140 | 
141 | # mypy
142 | .mypy_cache/
143 | .dmypy.json
144 | dmypy.json
145 | 
146 | # Pyre type checker
147 | .pyre/
148 | 
149 | # pytype static type analyzer
150 | .pytype/
151 | 
152 | # Cython debug symbols
153 | cython_debug/
154 | 
155 | # PyCharm
156 | #  JetBrains specific template is maintained in a separate JetBrains.gitignore that can
157 | #  be found at https://github.com/github/gitignore/blob/main/Global/JetBrains.gitignore
158 | #  and can be added to the global gitignore or merged into this file.  For a more nuclear
159 | #  option (not recommended) you can uncomment the following to ignore the entire idea folder.
160 | #.idea/
161 | 


--------------------------------------------------------------------------------
/samples/gen_webshells.yar:
--------------------------------------------------------------------------------
  1 | import "math"
  2 | // only needed for debugging of module math:
  3 | //import "console"
  4 | 
  5 | rule WEBSHELL_ASP_OBFUSC
  6 | {
  7 |     meta:
  8 |         description = "ASP webshell obfuscated"
  9 |         license = "Detection Rule License 1.1 https://github.com/Neo23x0/signature-base/blob/master/LICENSE"
 10 |         author = "Arnim Rupp (https://github.com/ruppde)"
 11 |         reference = "Internal Research"
 12 |         score = 75
 13 |         date = "2021/01/12"
 14 |         modified = "2023-07-05"
 15 |         hash = "ad597eee256de51ffb36518cd5f0f4aa0f254f27517d28fb7543ae313b15e112"
 16 |         hash = "e0d21fdc16e0010b88d0197ebf619faa4aeca65243f545c18e10859469c1805a"
 17 |         hash = "54a5620d4ea42e41beac08d8b1240b642dd6fd7c"
 18 |         hash = "fc44fd7475ee6c0758ace2b17dd41ed7ea75cc73"
 19 |         hash = "be2fedc38fc0c3d1f925310d5156ccf3d80f1432"
 20 |         hash = "3175ee00fc66921ebec2e7ece8aa3296d4275cb5"
 21 |         hash = "d6b96d844ac395358ee38d4524105d331af42ede"
 22 |         hash = "cafc4ede15270ab3f53f007c66e82627a39f4d0f"
 23 | 
 24 |     strings:
 25 |         $asp_obf1 = "/*-/*-*/" wide ascii
 26 |         $asp_obf2 = "u\"+\"n\"+\"s" wide ascii
 27 |         $asp_obf3 = "\"e\"+\"v" wide ascii
 28 |         $asp_obf4 = "a\"+\"l\"" wide ascii
 29 |         $asp_obf5 = "\"+\"(\"+\"" wide ascii
 30 |         $asp_obf6 = "q\"+\"u\"" wide ascii
 31 |         $asp_obf7 = "\"u\"+\"e" wide ascii
 32 |         $asp_obf8 = "/*//*/" wide ascii
 33 | 
 34 |         //strings from private rule capa_asp
 35 |         $tagasp_short1 = /<%[^"]/ wide ascii
 36 |         // also looking for %> to reduce fp (yeah, short atom but seldom since special chars)
 37 |         $tagasp_short2 = "%>" wide ascii
 38 | 
 39 |         // classids for scripting host etc
 40 |         $tagasp_classid1 = "72C24DD5-D70A-438B-8A42-98424B88AFB8" nocase wide ascii
 41 |         $tagasp_classid2 = "F935DC22-1CF0-11D0-ADB9-00C04FD58A0B" nocase wide ascii
 42 |         $tagasp_classid3 = "093FF999-1EA0-4079-9525-9614C3504B74" nocase wide ascii
 43 |         $tagasp_classid4 = "F935DC26-1CF0-11D0-ADB9-00C04FD58A0B" nocase wide ascii
 44 |         $tagasp_classid5 = "0D43FE01-F093-11CF-8940-00A0C9054228" nocase wide ascii
 45 |         $tagasp_long10 = "<%@ " wide ascii
 46 |         // <% eval
 47 |         $tagasp_long11 = /<% \w/ nocase wide ascii
 48 |         $tagasp_long12 = "<%ex" nocase wide ascii
 49 |         $tagasp_long13 = "<%ev" nocase wide ascii
 50 | 
 51 |         // <%@ LANGUAGE = VBScript.encode%>
 52 |         // <%@ Language = "JScript" %>
 53 | 
 54 |         // <%@ WebHandler Language="C#" class="Handler" %>
 55 |         // <%@ WebService Language="C#" Class="Service" %>
 56 | 
 57 |         // <%@Page Language="Jscript"%>
 58 |         // <%@ Page Language = Jscript %>
 59 |         // <%@PAGE LANGUAGE=JSCRIPT%>
 60 |         // <%@ Page Language="Jscript" validateRequest="false" %>
 61 |         // <%@ Page Language = Jscript %>
 62 |         // <%@ Page Language="C#" %>
 63 |         // <%@ Page Language="VB" ContentType="text/html" validaterequest="false" AspCompat="true" Debug="true" %>
 64 |         // <script runat="server" language="JScript">
 65 |         // <SCRIPT RUNAT=SERVER LANGUAGE=JSCRIPT>
 66 |         // <SCRIPT  RUNAT=SERVER  LANGUAGE=JSCRIPT>
 67 |         // <msxsl:script language="JScript" ...
 68 |         $tagasp_long20 = /<(%|script|msxsl:script).{0,60}language="?(vb|jscript|c#)/ nocase wide ascii
 69 | 
 70 |         $tagasp_long32 = /<script\s{1,30}runat=/ wide ascii
 71 |         $tagasp_long33 = /<SCRIPT\s{1,30}RUNAT=/ wide ascii
 72 | 
 73 |         // avoid hitting php
 74 |         $php1 = "<?php"
 75 |         $php2 = "<?="
 76 | 
 77 |         // avoid hitting jsp
 78 |         $jsp1 = "=\"java." wide ascii
 79 |         $jsp2 = "=\"javax." wide ascii
 80 |         $jsp3 = "java.lang." wide ascii
 81 |         $jsp4 = "public" fullword wide ascii
 82 |         $jsp5 = "throws" fullword wide ascii
 83 |         $jsp6 = "getValue" fullword wide ascii
 84 |         $jsp7 = "getBytes" fullword wide ascii
 85 | 
 86 |         $perl1 = "PerlScript" fullword
 87 | 
 88 | 
 89 |         //strings from private rule capa_asp_payload
 90 |         $asp_payload0  = "eval_r" fullword nocase wide ascii
 91 |         $asp_payload1  = /\beval\s/ nocase wide ascii
 92 |         $asp_payload2  = /\beval\(/ nocase wide ascii
 93 |         $asp_payload3  = /\beval\"\"/ nocase wide ascii
 94 |         // var Fla = {'E':eval};  Fla.E(code)
 95 |         $asp_payload4  = /:\s{0,10}eval\b/ nocase wide ascii
 96 |         $asp_payload8  = /\bexecute\s?\(/ nocase wide ascii
 97 |         $asp_payload9  = /\bexecute\s[\w"]/ nocase wide ascii
 98 |         $asp_payload11 = "WSCRIPT.SHELL" fullword nocase wide ascii
 99 |         $asp_payload13 = "ExecuteGlobal" fullword nocase wide ascii
100 |         $asp_payload14 = "ExecuteStatement" fullword nocase wide ascii
101 |         $asp_payload15 = "ExecuteStatement" fullword nocase wide ascii
102 |         $asp_multi_payload_one1 = "CreateObject" nocase fullword wide ascii
103 |         $asp_multi_payload_one2 = "addcode" fullword wide ascii
104 |         $asp_multi_payload_one3 = /\.run\b/ wide ascii
105 |         $asp_multi_payload_two1 = "CreateInstanceFromVirtualPath" fullword wide ascii
106 |         $asp_multi_payload_two2 = "ProcessRequest" fullword wide ascii
107 |         $asp_multi_payload_two3 = "BuildManager" fullword wide ascii
108 |         $asp_multi_payload_three1 = "System.Diagnostics" wide ascii
109 |         $asp_multi_payload_three2 = "Process" fullword wide ascii
110 |         $asp_multi_payload_three3 = ".Start" wide ascii
111 |         // this is about "MSXML2.DOMDocument" but since that's easily obfuscated, lets not search for it
112 |         $asp_multi_payload_four1 = "CreateObject" fullword nocase wide ascii
113 |         $asp_multi_payload_four2 = "TransformNode" fullword nocase wide ascii
114 |         $asp_multi_payload_four3 = "loadxml" fullword nocase wide ascii
115 | 
116 |         // execute cmd.exe /c with arguments using ProcessStartInfo
117 |         $asp_multi_payload_five1 = "ProcessStartInfo" fullword nocase wide ascii
118 |         $asp_multi_payload_five2 = ".Start" nocase wide ascii
119 |         $asp_multi_payload_five3 = ".Filename" nocase wide ascii
120 |         $asp_multi_payload_five4 = ".Arguments" nocase wide ascii
121 | 
122 | 
123 |         //strings from private rule capa_asp_write_file
124 |         // $asp_write1 = "ADODB.Stream" wide ascii # just a string, can be easily obfuscated
125 |         $asp_always_write1 = /\.write/ nocase wide ascii
126 |         $asp_always_write2 = /\.swrite/ nocase wide ascii
127 |         //$asp_write_way_one1 = /\.open\b/ nocase wide ascii
128 |         $asp_write_way_one2 = "SaveToFile" fullword nocase wide ascii
129 |         $asp_write_way_one3 = "CREAtEtExtFiLE" fullword nocase wide ascii
130 |         $asp_cr_write1 = "CreateObject(" nocase wide ascii
131 |         $asp_cr_write2 = "CreateObject (" nocase wide ascii
132 |         $asp_streamwriter1 = "streamwriter" fullword nocase wide ascii
133 |         $asp_streamwriter2 = "filestream" fullword nocase wide ascii
134 | 
135 |         //strings from private rule capa_asp_obfuscation_multi
136 |         // many Chr or few and a loop????
137 |         //$loop1 = "For "
138 |         //$o1 = "chr(" nocase wide ascii
139 |         //$o2 = "chr (" nocase wide ascii
140 |         // not excactly a string function but also often used in obfuscation
141 |         $o4 = "\\x8" wide ascii
142 |         $o5 = "\\x9" wide ascii
143 |         // just picking some random numbers because they should appear often enough in a long obfuscated blob and it's faster than a regex
144 |         $o6 = "\\61" wide ascii
145 |         $o7 = "\\44" wide ascii
146 |         $o8 = "\\112" wide ascii
147 |         $o9 = "\\120" wide ascii
148 |         //$o10 = " & \"" wide ascii
149 |         //$o11 = " += \"" wide ascii
150 |         // used for e.g. "scr"&"ipt"
151 | 
152 |         $m_multi_one1 = "Replace(" wide ascii
153 |         $m_multi_one2 = "Len(" wide ascii
154 |         $m_multi_one3 = "Mid(" wide ascii
155 |         $m_multi_one4 = "mid(" wide ascii
156 |         $m_multi_one5 = ".ToString(" wide ascii
157 | 
158 |         /*
159 |         $m_multi_one5 = "InStr(" wide ascii
160 |         $m_multi_one6 = "Function" wide ascii
161 | 
162 |         $m_multi_two1 = "for each" wide ascii
163 |         $m_multi_two2 = "split(" wide ascii
164 |         $m_multi_two3 = " & chr(" wide ascii
165 |         $m_multi_two4 = " & Chr(" wide ascii
166 |         $m_multi_two5 = " & Chr (" wide ascii
167 | 
168 |         $m_multi_three1 = "foreach" fullword wide ascii
169 |         $m_multi_three2 = "(char" wide ascii
170 | 
171 |         $m_multi_four1 = "FromBase64String(" wide ascii
172 |         $m_multi_four2 = ".Replace(" wide ascii
173 |         $m_multi_five1 = "String.Join(\"\"," wide ascii
174 |         $m_multi_five2 = ".Trim(" wide ascii
175 |         $m_any1 = " & \"2" wide ascii
176 |         $m_any2 = " += \"2" wide ascii
177 |         */
178 | 
179 |         $m_fp1 = "Author: Andre Teixeira - andret@microsoft.com" /* FPs with 0227f4c366c07c45628b02bae6b4ad01 */
180 |         $m_fp2 = "DataBinder.Eval(Container.DataItem" ascii wide
181 | 
182 | 
183 |         //strings from private rule capa_asp_obfuscation_obviously
184 |         $oo1 = /\w\"&\"\w/ wide ascii
185 |         $oo2 = "*/\").Replace(\"/*" wide ascii
186 | 
187 |     condition:
188 |         filesize < 100KB and (
189 |         (
190 |             any of ( $tagasp_long* ) or
191 |             // TODO :  yara_push_private_rules.py doesn't do private rules in private rules yet
192 |             any of ( $tagasp_classid* ) or
193 |             (
194 |                 $tagasp_short1 and
195 |                 $tagasp_short2 in ( filesize-100..filesize )
196 |             ) or (
197 |                 $tagasp_short2 and (
198 |                     $tagasp_short1 in ( 0..1000 ) or
199 |                     $tagasp_short1 in ( filesize-1000..filesize )
200 |                 )
201 |             )
202 |         ) and not (
203 |             (
204 |                 any of ( $perl* ) or
205 |                 $php1 at 0 or
206 |                 $php2 at 0
207 |             ) or (
208 |                 ( #jsp1 + #jsp2 + #jsp3 ) > 0 and ( #jsp4 + #jsp5 + #jsp6 + #jsp7 ) > 0
209 |                 )
210 |         )
211 |         )
212 |         and
213 |         ( ( (
214 |             any of ( $asp_payload* ) or
215 |         all of ( $asp_multi_payload_one* ) or
216 |         all of ( $asp_multi_payload_two* ) or
217 |         all of ( $asp_multi_payload_three* ) or
218 |         all of ( $asp_multi_payload_four* ) or
219 |         all of ( $asp_multi_payload_five* )
220 |         )
221 |         or (
222 |         any of ( $asp_always_write* ) and
223 |         (
224 |             any of ( $asp_write_way_one* ) and
225 |             any of ( $asp_cr_write* )
226 |         ) or (
227 |             any of ( $asp_streamwriter* )
228 |         )
229 |         )
230 |         ) and
231 |         ( (
232 |         (
233 |             filesize < 100KB and
234 |             (
235 |                 //( #o1+#o2 ) > 50 or
236 |                 ( #o4+#o5+#o6+#o7+#o8+#o9 ) > 20
237 |             )
238 |         ) or (
239 |             filesize < 5KB and
240 |             (
241 |                 //( #o1+#o2 ) > 10 or
242 |                 ( #o4+#o5+#o6+#o7+#o8+#o9 ) > 5 or
243 |                 (
244 |                     //( #o1+#o2 ) > 1 and
245 |                     ( #m_multi_one1 + #m_multi_one2 + #m_multi_one3 + #m_multi_one4 + #m_multi_one5 ) > 3
246 |                 )
247 | 
248 |             )
249 |         ) or (
250 |             filesize < 700 and
251 |             (
252 |                 //( #o1+#o2 ) > 1 or
253 |                 ( #o4+#o5+#o6+#o7+#o8+#o9 ) > 3 or
254 |                 ( #m_multi_one1 + #m_multi_one2 + #m_multi_one3 + #m_multi_one4 + #m_multi_one5 ) > 2
255 |             )
256 |         )
257 |         )
258 |         or any of ( $asp_obf* ) ) or (
259 |         (
260 |             filesize < 100KB and
261 |             (
262 |                 ( #oo1 ) > 2 or
263 |                 $oo2
264 |             )
265 |         ) or (
266 |             filesize < 25KB and
267 |             (
268 |                 ( #oo1 ) > 1
269 |             )
270 |         ) or (
271 |             filesize < 1KB and
272 |             (
273 |                 ( #oo1 ) > 0
274 |             )
275 |         )
276 |         )
277 |         )
278 |         and not any of ( $m_fp* )
279 | }
280 | 
281 | 


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/README.md:
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  1 | # YARA-Style-Guide
  2 | A specification and style guide for YARA rules
  3 | 
  4 | ## Introduction 
  5 | 
  6 | YARA is a powerful and versatile tool for malware detection, used by security researchers and analysts all over the world. YARA rules are at the heart of this tool, providing a structured way to identify and classify malware based on various characteristics such as file names, sizes, and contents.
  7 | 
  8 | Creating effective YARA rules is not an easy task, and it requires a deep understanding of the malware landscape, as well as knowledge of YARA's syntax and capabilities. To help security professionals create high-quality and efficient YARA rules, we have created this style guide.
  9 | 
 10 | This guide will cover the best practices for YARA rule structure and contents, including recommendations for naming conventions, syntax, and content selection. By following these guidelines, you will be able to create YARA rules that are accurate, concise, and easy to read and maintain.
 11 | 
 12 | Whether you are a seasoned security professional or just getting started with YARA, this guide will provide you with the tools you need to create effective malware detection rules.
 13 | 
 14 | ## Scope
 15 | 
 16 | This YARA Style Guide is primarily focused on enhancing readability, maintainability, and usability of YARA rules. It doesn’t delve into the aspects of performance or resource utilization, although adhering to these best practices can inadvertently lead to optimized rule set performance. (e.g., the order of the expressions in the condition)
 17 | 
 18 | For in-depth insights and strategies on performance and resource optimization, we recommend exploring [this project](https://github.com/Neo23x0/YARA-Performance-Guidelines/).
 19 | 
 20 | ## Rule Names
 21 | 
 22 | ```yara
 23 | rule TBD
 24 | ```
 25 | 
 26 | ## Rule Name
 27 | 
 28 | The rule name is sometimes the only or first piece of information that is shown to a user. Therefore it should already include information about the type of threat, tags that classify the threat, a descriptive identifier and even an information about the context or a period in which the rule was created. 
 29 | 
 30 | The different values are separated by an underscore character (`_`). 
 31 | 
 32 | The values are ordered from generic to specific.
 33 | 
 34 | The most generic values are the category of the threat. The following list contains the most common generic classifiers.
 35 | 
 36 | ### Main Categories
 37 | 
 38 | - **MAL** (malware) : used for malware
 39 | - **HKTL** (hacktool) : used for hack tools
 40 | - **WEBSHELL** : used for web shells
 41 | - **EXPL** (exploit) : used for exploit codes (e.g., proof-of-concept code, exploit payloads etc.)
 42 | - **VULN** (vulnerability) : used for vulnerabilities (e.g., a vulnerable driver, a vulnerable JAVA library etc.)
 43 | - **SUSP** (suspicious) : used for all kinds of anomalies, suspicious capabilities (e.g., obfuscated code, shell codes, suspicious combination of imports, suspicious set of commands in a script etc.)
 44 | - **PUA** : used for possibly unwanted applications
 45 | 
 46 | Other categories that proofed to be useful when classifying YARA rules:
 47 | 
 48 | Important: the lists are not exhaustive and can be extended at any time if necessary. 
 49 | 
 50 | ### Intention / Background
 51 | 
 52 | - **APT** (advanced persistent threat): used to indicate that the 
 53 | - **CRIME** (crime group activity): 
 54 | - **ANOMALY** (generic and suspicious characteristics)
 55 | - **RANSOM**
 56 | 
 57 | ### Types of Malware / File
 58 | 
 59 | - **RAT**
 60 | - **Implant**
 61 | - **Stealer**
 62 | - **Loader**
 63 | - **Crypter**
 64 | - **PEEXE** (often omitted)
 65 | - **DRV** : used for drivers
 66 | 
 67 | ### Operating System
 68 | 
 69 | - **WIN** (often omitted)
 70 | - **LNX**
 71 | - **MacOS**
 72 | 
 73 | ### Architecture
 74 | 
 75 | - **X64** (often omitted)
 76 | - **X86** (often omitted)
 77 | - **ARM**
 78 | - **SPARC**
 79 | 
 80 | ### Technology
 81 | 
 82 | - **PE** (often omitted) / - **ELF**
 83 | - **PS** / **PS1** / **VBS** / **BAT** / **JS**
 84 | - **NET** / **GO** / **Rust**
 85 | - **PHP** / **JSP** / **ASP**
 86 | - **MalDoc**
 87 | - **LNK**
 88 | - **ZIP**
 89 | - **RAR**
 90 | 
 91 | ### Modifiers
 92 | 
 93 | - **OBFUSC** : used for obfuscated samples 
 94 | - **Encoded** : used for encoded versions of payloads
 95 | - **Unpacked** : used for unpacked payloads
 96 | - **InMemory** : used for code that can only be found when loaded into memory
 97 | 
 98 | ### Packers / Installers
 99 | 
100 | - **SFX** : used for self-extracting archives
101 | - **UPX**
102 | - **Themida**
103 | - **NSIS**
104 | 
105 | ### Threat Actor Identifiers
106 | 
107 | The threat actor identifier tags are straight forward. 
108 | 
109 | The list only contains examples:
110 | 
111 | - **APT28**
112 | - **UNC4736**
113 | - **Lazarus**
114 | 
115 | ### Threat Identifiers
116 | 
117 | The threat identifier tags are straight forward. 
118 | 
119 | - **CobaltStrike**
120 | - **PlugX**
121 | - **QakBot**
122 | 
123 | ### Other Often Used Keywords
124 | 
125 | - **TINY** : used for very small files
126 | - **HUGE** : used for very big files
127 | - **UAC_Bypass**
128 | - **Base64**
129 | 
130 | ### Suffixes to Guarantee Uniqueness
131 | 
132 | The suffixes lower the chances that two analysts choose the same rule name by adding values to the rule.
133 | 
134 | The recommended values are:
135 | 
136 | - **MonthYear** : e.g., `May23`, `Jan19`
137 | - **Number** : e.g., `*_1`, `*_2`
138 | 
139 | ### Combining the Categories
140 | 
141 | The mentioned keywords are combined to create a more specific classification.
142 | 
143 | Here are some examples:
144 | 
145 | - `SUSP_APT_*`: used for forensic artifacts found on systems compromised by a threat actor (e.g., hack tool outputs, command line flag combinations, redirected standard outputs, log file contents etc.)
146 | - `MAL_CRIME_RANSOM_LNX_Rust_*` : used for malware used by ransomware crime groups written in Rust for the Linux platform
147 | - `WEBSHELL_APT_ASP_*` : used for ASP webshell used by nation state threat actors 
148 | 
149 | ### Full Rule Name Examples
150 | 
151 | - `APT_MAL_CozyBear_ELF_Loader_Apr18` : Rule written in April 2018 for a loader used by the threat actor Cozy Bear written for the Linux platform. 
152 | - `SUSP_Anomaly_LNK_Huge_Apr22` : Rule written in April 2022 for suspiciously big link files
153 | - `MAL_CRIME_RANSOM_PS1_OBFUSC_Loader_May23` : Rule written in May 2023xw for an obfuscated PowerShell loader noticed in a Ransomware campaign
154 | 
155 | 
156 | ## Rule Structure and Values
157 | 
158 | ```yara
159 | rule RULE_NAME : TAGS {
160 |     meta:
161 |         description = "Detects ..."
162 |         author = "Author Name / Company / Org"
163 |         date = "YYYY-MM-DD"
164 |         reference = "URL / Internal Research"
165 |         [OPTIONAL META DATA FIELDS]
166 |     strings:
167 |         $string1 = "value"
168 |     condition:
169 |         header_check
170 |         file_size_limitation
171 |         other_limitations
172 |         string_combinations
173 |         false_positive_filters
174 | }
175 | ```
176 | 
177 | 
178 | ## Indentation
179 | 
180 | Utilize indentation to enhance the readability of your YARA rules. It's common practice to use either 3 or 4 spaces or tabs for indentation in most published rules. This consistency aids in maintaining a clean and organized presentation of the code, making it easier to read and understand.
181 | 
182 | DON'T
183 | ```yara
184 | rule MY_RULE {
185 | meta:
186 | description = "my test rule"
187 | author = "John Galt"
188 | strings:
189 | $s1 = "eval("
190 | $s2 = "WScript.Shell"
191 | condition:
192 | filesize < 10KB and all of them 
193 | }
194 | 
195 | rule MY_RULE {
196 |  meta:
197 |   description = "my test rule"
198 |   author = "John Galt"
199 |  strings:
200 |   $s1 = "eval("
201 |   $s2 = "WScript.Shell"
202 |  condition:
203 |   filesize < 10KB and all of them 
204 | }
205 | ```
206 | 
207 | DO
208 | ```yara
209 | rule MY_RULE {
210 |    meta:
211 |       description = "my test rule"
212 |       author = "John Galt"
213 |    strings:
214 |       $s1 = "eval("
215 |       $s2 = "WScript.Shell"
216 |    condition:
217 |       filesize < 10KB and all of them 
218 | }
219 | ```
220 | 
221 | ### Rule Tags
222 | 
223 | While rule tags can be employed to classify and group related rules together, in this guide, we advise incorporating main categories directly into the rule name for more straightforward identification. Additional tags that are less directly related to the main category should be included in a dedicated meta data field called "tags". This approach keeps rule names concise while also offering the flexibility to include more context-specific tags.
224 | 
225 | The chapter on the rule names explains how to include main categories in the rule name:
226 | 
227 | ```yara
228 | rule RULE_NAME_MAIN_CATEGORY1_MAIN_CATEGORY2 {
229 |     ...
230 | }
231 | ```
232 | 
233 | For additional, less directly related tags, you can add them to the tags field in the meta data section:
234 | 
235 | ```yara
236 | rule RULE_NAME {
237 |     meta:
238 |         tags = "TAG1, TAG2, TAG3"
239 |     ...
240 | }
241 | ```
242 | 
243 | These tags can denote a variety of attributes such as threat actor names (e.g., APT28, Lazarus), malware families (e.g., Emotet, TrickBot), or types of attacks (e.g., phishing, ransomware). See the chapter on rule names for details.
244 | 
245 | ## Rule Meta Data
246 | 
247 | The meta section provides additional information about the rule. This can include the author's name, a reference to the research paper or blog post that describes the malware, the date when the rule was written, or any other information that you consider relevant.
248 | 
249 | ```yara
250 | rule RULE_NAME : TAGS {
251 |     meta:
252 |         description = "Detects ..."
253 |         author = "Author Name / Company / Org"
254 |         date = "YYYY-MM-DD"
255 |         reference = "URL / Internal Research"
256 |         score = [0-100]
257 |         [OPTIONAL META DATA FIELDS]
258 |     ...
259 | }
260 | ```
261 | 
262 | As the name suggests, the optional meta fields are not required for the rule to function, but they can provide valuable context to anyone who uses the rule.
263 | 
264 | ### Mandatory Meta Data Fields
265 | 
266 | Certain meta data fields are indispensable as they contain critical information for analysts who work with the rule or evaluate rule matches.
267 | 
268 | - `description`: This should provide a clear and succinct description of what the rule is designed to detect.
269 | - `author`: This field specifies the author, group, or organization that composed or released the rule.
270 | - `reference`: This should link to a report, source code repository, website, private report name, identifier, or a short description of the source from which the rule was derived.
271 | - `date`: This denotes the creation date of the rule and should be in the format YYYY-MM-DD.
272 | 
273 | The following chapters describe the values in more detail. 
274 | 
275 | #### Description
276 | 
277 | | Field  | Description                                  |
278 | |--------|----------------------------------------------|
279 | | Value | String |
280 | | Preferred Length | 60-400 characters |
281 | | Avoid | URLs |
282 | | Prefer | Value starts with "Detects ..." |
283 | 
284 | The "Description" field plays a crucial role in conveying the core intent and scope of a YARA rule. Here's a guide to constructing an effective description:
285 | 
286 | Preferred Length: It's recommended to keep the description between 60 to 400 characters. This range ensures the description is concise, yet provides enough information for analysts and other users to understand the rule's purpose without overwhelming them.
287 | 
288 | Avoid URLs: Refrain from including URLs directly in the description. If a reference is necessary, it's better to use the reference meta field or another dedicated field for URLs.
289 | 
290 | Starting Convention: Start your description with the phrase "Detects ...". This format offers clarity, ensuring users can quickly ascertain what the YARA rule identifies or monitors.
291 | 
292 | #### Author
293 | 
294 | | Field  | Description                                  |
295 | |--------|----------------------------------------------|
296 | | Value | String |
297 | | Avoid | URLs |
298 | | Prefer | Full name, Twitter handles |
299 | 
300 | The "Author" field provides attribution and aids in understanding the provenance of a YARA rule. Here's how to best structure this field:
301 | 
302 | Preferred Length: There's no strict length guideline for the "Author" field. However, clarity and brevity are always appreciated.
303 | 
304 | Avoid URLs: Direct URLs shouldn't be placed in the "Author" field. If you need to provide additional information about the author or the source, consider using other meta fields or providing accompanying documentation.
305 | 
306 | Author Identification: It's best to use the full name of the author for clear attribution. If you want to give credit using a social media identifier, Twitter handles are preferable.
307 | 
308 | Multiple Authors: If a rule is a result of collaborative work, instead of using the "Author" field multiple times, consolidate the authors into a single field using a comma-separated list. This ensures the meta section remains tidy and concise.
309 | 
310 | #### Reference
311 | 
312 | | Field  | Description                                  |
313 | |--------|----------------------------------------------|
314 | | Value | List of Strings |
315 | | Avoid | Unstable links, links to private resources |
316 | | Prefer | URLs |
317 | 
318 | The "Reference" field is crucial for providing context and background information regarding the YARA rule. Here's a guide to populating this field optimally:
319 | 
320 | What Can a Reference Be? A reference can be a direct link to a report from which the YARA rule was derived, copied, or where the specific rule can be found. This provides clarity on the rule's origins and its foundational evidence.
321 | 
322 | Preferred Length: While there isn't a hard limit on the length for the "Reference" field, it's essential that any references provided are concise and directly relevant.
323 | 
324 | Avoid Unstable Links and Private Resources: It's best not to include URLs that might become inactive in the near future, rendering the reference useless. Additionally, links that lead to private, restricted, or paywalled resources should be avoided, as they may not be accessible to all users.
325 | 
326 | Preference for URLs: When providing references, it's optimal to use direct URLs that lead to public and stable sources of information, such as research papers, blog posts, or official advisories.
327 | 
328 | Internal Work: If the YARA rule is derived from your own research, ideas, or observations rather than from external publications, it's appropriate to use "Internal Research" as the value for the reference. This indicates that the rule's origin is proprietary and not directly linked to an external public source.
329 | 
330 | #### Date
331 | 
332 | | Field  | Description                                  |
333 | |--------|----------------------------------------------|
334 | | Value | String |
335 | | Preferred Format | YYYY-MM-DD |
336 | 
337 | The "Date" field serves as a crucial indicator of when a YARA rule was initially formulated. This timestamp is essential to understand the context and timing of the rule's creation. Here's how you can optimally populate this field:
338 | 
339 | Format Requirement: When inputting the date for your rule, ensure that you use the format "YYYY-MM-DD". This standardized format ensures consistency across all rules and ease of understanding for analysts and researchers.
340 | 
341 | Reflecting the Creation Date: It's essential to note that the "Date" field should exclusively indicate when the rule was originally created. It is not meant to showcase when the rule was published or any subsequent modifications made to it.
342 | 
343 | Modifications: If you make any changes to a YARA rule after its original creation, you should indicate this in a separate field named "modified". This distinction ensures clarity about the rule's original inception and any updates that may have been made subsequently.
344 | 
345 | ### Optional Meta Data Fields
346 | 
347 | While mandatory meta data fields provide essential information about a YARA rule, optional fields offer supplementary details that can further enhance the context, functionality, and traceability of the rule. They're particularly useful for providing additional search parameters, recording changes, and maintaining rule versioning.
348 | 
349 | - `hash`: This field can hold one or more MD5, SHA1, SHA256 values. You can use the hash field multiple times if needed. It can be a list of hash values. The SHA256 hash is the preferred value. 
350 | - `score`: A numerical score between 0 and 100, which is used to represent a combination of the rule's severity (how critical the threat it identifies is) and specificity (how uniquely the rule identifies a particular threat). The score can aid in prioritizing responses to rule matches, e.g. rules with higher score are more critical. 
351 | - `modified`: This specifies the last modification date of the rule, which is useful when the rule gets updated post its initial creation. The date should be in the YYYY-MM-DD format.
352 | - `old_rule_name`: This is used to hold the previous name of the rule. It allows for searches using the old name in case the name has been changed.
353 | tags: This is used to include a list of tags. Each tag should be separated by a comma.
354 | - `license`: A license under which the rule has been released.
355 | 
356 | #### Hash 
357 | 
358 | | Field  | Description                                  |
359 | |--------|----------------------------------------------|
360 | | Value | List of Strings |
361 | | Avoid | N/A |
362 | | Prefer | SHA256 hash |
363 | 
364 | The "Hash" field in a YARA rule is integral to the detection process, as it provides a distinct identifier for the file to be matched. Properly populating this field ensures optimal rule execution and precise matching. Here are some guidelines to consider:
365 | 
366 | Hash Type: While you might encounter various hash types, it's preferable to use the SHA256 hash. It offers a higher level of specificity and reduces the likelihood of collisions compared to some other hash types.
367 | 
368 | Direct File Reference: The hash should directly correlate to the file that the YARA rule is intended to match. This ensures that the rule effectively detects the intended threat without false positives.
369 | 
370 | Avoid Archive Hashes: It's essential to avoid using hashes of archives where the sample might have been found. Instead, focus on the extracted file or the malicious content itself. By doing so, you ensure that the detection is specific to the threat and not the container it might have come in.
371 | 
372 | Exception for Memory-based Matches: An exception to the above is when your rule is designed to detect samples loaded into memory. In scenarios where the rule might not detect a sample on disk but identifies the unpacked, unencrypted, or loaded sample in memory, the hash related to that memory form should be used.
373 | 
374 | #### Score 
375 | 
376 | | Field  | Description                                  |
377 | |--------|----------------------------------------------|
378 | | Value | Number|
379 | | Range | 0-100 |
380 | 
381 | The "Score" field in a YARA rule plays a pivotal role in gauging the potential impact and uniqueness of a detected threat. This field incorporates two key dimensions: the severity of the detected threat and the specificity of the rule in identifying it. Here's a breakdown of what you should know:
382 | 
383 | Value Range: The score is a numerical value ranging between 0 and 100. It's not just an arbitrary number; it offers an insight into the potential risks associated with a rule match.
384 | 
385 | Severity and Specificity: This score embodies two essential characteristics:
386 | 
387 | Severity: It indicates how critical or detrimental the detected threat is. A high severity score points to potentially significant damage or impact if the threat is not addressed.
388 | Specificity: It tells you how uniquely the rule identifies a particular threat, ensuring that it's not just catching benign or unrelated items.
389 | Response Prioritization: One of the most significant utilities of the score is in threat response prioritization. When inundated with numerous rule matches, security analysts can prioritize responses based on the score. A higher score typically suggests that the rule match is more critical and should be addressed with higher urgency.
390 | 
391 | Incorporating a well-thought-out score in your YARA rules ensures a more strategic and effective approach to threat detection and response.
392 | 
393 | Use this table as a guideline to assign a score, ensuring that your rule appropriately represents the threat level:
394 | 
395 | | Score Range | Significance Level                         | Examples & Use Cases                                                           |
396 | |-------------|--------------------------------------------|--------------------------------------------------------------------------------|
397 | | 0-39        | Very Low Significance                      | Capabilities, packers etc. (often combined for a higher total score)            |
398 | | 40-59       | Noteworthy                                 | Uncommon packers or those often used by malware, PE header anomalies            |
399 | | 60-79       | Suspicious                                 | Heuristics matches, obfuscation rules, generic detection rules                  |
400 | | 80-100      | High (Direct matches on malware/hack tools)| Malware, hack tools, and other malicious entities identified with high accuracy |
401 | 
402 | ## Rule Strings
403 | 
404 | The strings section of a YARA rule specifies the sequences of bytes, strings, or regular expressions that will be searched for within the file. Each string is given a unique identifier that can be used in the condition section to refer to the string.
405 | 
406 | ```yara
407 | rule RULE_NAME {
408 |     ...
409 |     strings:
410 |         $s1 = "value"
411 |         $s2 = { E2 34 F1 67 }
412 |         $r1 = /abc[def]+/
413 |     ...
414 | }
415 | ```
416 | 
417 | In the example above, `$s1` is a simple string, `$s2` is a sequence of bytes, and `$r1` is a regular expression.
418 | 
419 | ### String Identifiers
420 | 
421 | There are some best practices in regards to the use of string values in YARA.
422 | 
423 | Opt for Readable String Values
424 | For enhanced readability, avoid using hexadecimal representation for string values that can be effectively represented with standard strings. Exceptions to this rule include strings containing control characters like \t (tab) or \n (newline), where the hexadecimal format is preferred.
425 | 
426 | Avoid:
427 | 
428 | ```yara
429 | $s1 = { 46 72 6F 6D 42 61 73 65 36 34 53 74 72 69 6E 67 28 }
430 | ```
431 | 
432 | Recommended:
433 | 
434 | ```yara
435 | $s1 = "FromBase64String("
436 | ```
437 | 
438 | #### Choose Efficient String Identifiers
439 | 
440 | Opt for concise or descriptive identifiers for strings to enhance the readability of your YARA rules. Avoid long, non-descriptive identifiers, as they can clutter the code and make conditions, especially complex ones, difficult to read and understand.
441 | 
442 | Avoid:
443 | 
444 | ```yara
445 |    $string_value_footer_1 = "eval("
446 |    $selection_14 = "eval("
447 | ...
448 | condition:
449 |    all of (selection_*) and 3 of ($string_value_footer)
450 | ```
451 | Recommended:
452 | 
453 | ```yara
454 |    $s1 = "eval("
455 |    $eval = "eval("
456 | condition:
457 |    all of (s*) and $eval
458 | ```
459 | 
460 | Incorporating these practices ensures your YARA rules are not only functional but also user-friendly, fostering an environment of efficiency and collaboration among security professionals.
461 | 
462 | ### Hex Identifiers
463 | 
464 | For hexadecimal representations that primarily consist of ASCII characters, it’s helpful to include the ASCII string representation or the readable portions thereof in a comment, enhancing understandability.
465 | 
466 | ```yara
467 |    /* )));\nIEX( */
468 |    $s1 = { 29 29 29 3b 0a 49 45 58 28 0a }
469 | ```
470 | 
471 | To enhance readability, it's advisable to segment hex identifiers at every 16-byte interval. This practice is particularly beneficial for lengthy values, allowing observers to quickly gauge the length of the value without the need to horizontally scroll through the code.
472 | 
473 | ```yara
474 |    $s1 = { 2c 20 2a 79 6f 77 2e 69 20 26 20 30 78 46 46 29 
475 |            3b 0a 20 20 70 72 69 6e 74 66 20 28 28 28 2a 79 
476 |            6f 77 2e 69 20 26 20 30 78 66 66 29 20 3d 3d 20 
477 |            30 78 34 31 29 20 3f 20 22 4c 49 54 54 4c 45 5c 
478 |            6e 22 20 3a 20 22 42 49 47 5c 6e 22 29 3b 0a 20 
479 |            20 70 72 69 6e 74 66 20 28 22 73 68 6f 72 74 20 
480 |            25 64 3b 20 20 69 6e 74 }
481 | ```
482 | 
483 | ### Regular Expressions
484 | 
485 | TBD
486 | 
487 | ### Categorizing Strings: The Triad Approach ($x*, $s*, $a*)
488 | 
489 | Understanding the categorization of strings is crucial in enhancing the efficiency and accuracy of YARA rules. We propose a three-category approach to organize and identify strings effectively:
490 | 
491 | 1. **Highly Specific Strings ($x*)**
492 |    - These are unique identifiers, characterized by their specificity to a particular threat. Their occurrence is almost exclusively associated with the intended target, making them highly reliable indicators.
493 |    - **Notation:** We designate these strings with an `x` prefix.
494 | 
495 | 2. **Grouped Strings ($s*)**
496 |    - These strings may not be distinctive individually but become significant when considered as part of a collective group. These sets of strings, though not unique on their own, can be indicative of a threat when found together.
497 |    - **Notation:** They are marked with an `s` prefix to indicate their collective utility.
498 | 
499 | 3. **Pre-Selection Strings ($a*)**
500 |    - These are commonly found strings that don’t directly indicate a threat but are instrumental in narrowing down the file type or format under scrutiny. They play a pivotal role in optimizing the rule's performance by limiting the scope of the search.
501 |    - **Notation:** An `a` prefix is used to identify these auxiliary strings.
502 | 
503 | Example:
504 | 
505 | ```yara
506 | rule HKTL_Go_EasyHack_Oct23 {
507 |    meta:
508 |       description = "Detects a Go based hack tool"
509 |       author = "John Galt"
510 |       date = "2023-09-13"
511 |       reference = "https://githoop.com/EdgyHackerFreak/EasyHack"
512 |    strings:
513 |       $a1 = "Go build"
514 | 
515 |       $x1 = "Usage: easyhack.exe -t [IP] -p [PORT]"
516 |       $x2 = "c0d3d by @EdgyHackerFreak"
517 | 
518 |       $s1 = "main.inject"
519 |       $s2 = "main.loadPayload"
520 |    condition:
521 |       uint16(0) == 0x5a4d
522 |       and filesize < 20MB
523 |       and $a1 
524 |       and (
525 |         1 of ($x*)
526 |         or all of ($s*)
527 |       )
528 |       or 4 of them
529 | }
530 | ```
531 | 
532 | ### False Positive Filters ($f*)
533 | 
534 | False positives can hinder the effectiveness of YARA rules. To address this, we introduce a method to manage potential false positives.
535 | 
536 | - Strings that might indicate benign or non-malicious patterns should be prefixed with `fp`
537 | - If a rule matches malicious patterns but also matches a `$fp*` string, the rule doesn't trigger
538 | 
539 | ```yara
540 | rule HKTL_Go_EasyHack_Oct23 {
541 |    meta:
542 |       description = "Detects a Go based hack tool"
543 |       author = "John Galt"
544 |    strings:
545 |       $a1 = "Go build"
546 | 
547 |       $s1 = "main.inject"
548 |       $s2 = "main.loadPayload"
549 | 
550 |       $fp1 = "Copyright by CrappySoft" wide
551 |    condition:
552 |       uint16(0) == 0x5a4d
553 |       and filesize < 20MB
554 |       and $a1 
555 |       and all of ($s*)
556 |       and not 1 of ($fp*)
557 | }
558 | ```
559 | 
560 | ## Rule Condition
561 | 
562 | The condition section of a YARA rule specifies the conditions that must be met for the rule to be considered a match. This is where the magic of YARA really happens. Conditions can be simple or complex, combining multiple strings, byte sequences, and metadata checks.
563 | 
564 | ```yara
565 | rule RULE_NAME : TAGS {
566 |     ...
567 |     condition:
568 |         header_check
569 |         file_size_limitation
570 |         other_limitations
571 |         string_combinations
572 |         false_positive_filters
573 | }
574 | ```
575 | 
576 | In the example above, the condition would be met if the checks in header_check, file_size_limitation, other_limitations, string_combinations and false_positive_filters are true. It's important to write conditions in a way that optimizes performance, especially when dealing with large data sets or live traffic.
577 | 
578 | Remember, the conditions should reflect the detection logic of your rule, be it based on the presence of certain strings, file size restrictions, or other characteristics that define your target threat. Be cautious while defining conditions, as too broad or too lenient conditions might lead to a high number of false positives.
579 | 
580 | ### Examples
581 | 
582 | ```yara
583 | rule RULE_NAME : TAGS {
584 |     ...
585 |     condition:
586 |         uint16(0) == 0x5a4d 
587 |         and filesize < 300KB 
588 |         and pe.number_of_signature == 0
589 |         and all of ($s*)
590 |         and not 1 of ($fp*)
591 | }
592 | ```
593 | 
594 | For improved clarity, it's advised to place a new line before the and keyword. Experience has demonstrated that this approach enhances readability, making rules quicker to understand.
595 | 
596 | When parts of the condition need to be combined using an or operator, it's recommended to encapsulate these components within an indented block:
597 | 
598 | ```yara
599 | rule RULE_NAME : TAGS {
600 |     ...
601 |     condition:
602 |         uint16(0) == 0x5a4d 
603 |         and filesize < 300KB 
604 |         and pe.number_of_signature == 0
605 |         and (
606 |             1 of ($x*)
607 |             or 3 of them
608 |         )
609 |         and not 1 of ($fp*)
610 | }
611 | ```
612 | 
613 | ```yara
614 | rule RULE_NAME : TAGS {
615 |     ...
616 |     condition:
617 |         uint16(0) == 0x5a4d 
618 |         and filesize < 300KB 
619 |         and (
620 |             1 of ($x*)
621 |             or (
622 |                 2 of ($s*) 
623 |                 and 3 of them
624 |             )
625 |         )
626 | }
627 | ```
628 | 
629 | For conditions that require the evaluation of multiple potential values, such as different file markers, the same indented block format should be applied:
630 | 
631 | ```yara
632 | rule RULE_NAME : TAGS {
633 |     ...
634 |     condition:
635 |         (
636 |             uint16(0) == 0x5a4d     // MZ marker
637 |             or uint16(0) == 0x457f  // ELF marker
638 |         )
639 |         and filesize < 300KB 
640 |         and pe.number_of_signature == 0
641 |         and all of ($s*)
642 |         and not 1 of ($fp*)
643 | }
644 | ```
645 | 
646 | Adhering to this format fosters easy readability and promotes a clean, structured presentation of the rule conditions.
647 | 
648 | ## Tweaks
649 | 
650 | ### String Matching FTW
651 | 
652 | It’s not uncommon for some to leverage looping and hashing techniques to identify patterns within the PE headers of files, as illustrated below. In this example, the author iteratively calculates the MD5 hash of the initial 256 bytes of code across all PE sections and contrasts it with a predetermined hash value.
653 | 
654 | ```yara
655 |    condition:
656 |       for any var_sect in pe.sections:
657 |          (hash.md5( var_sect.raw_data_offset, 0x100 ) == "d99eb1e503cac3a1e90450d0c07e3ffc" )
658 | ```
659 | 
660 | However, this approach is less efficient than it might initially appear. YARA is intrinsically designed for direct string and pattern matching, making it highly efficient in these tasks. Conversely, cycling through each section and calculating hashes can be resource-intensive and less optimal.
661 | 
662 | A more streamlined and efficient approach is to directly incorporate the 256 bytes as a hexadecimal string within the YARA rule. This modification bypasses the computational overhead of hashing and leverages YARA's innate efficiency in string matching, ensuring rapid and precise detection without unnecessary CPU consumption.
663 | 


--------------------------------------------------------------------------------
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255 |     customarily used for software interchange.
256 | 
257 |     b) Convey the object code in, or embodied in, a physical product
258 |     (including a physical distribution medium), accompanied by a
259 |     written offer, valid for at least three years and valid for as
260 |     long as you offer spare parts or customer support for that product
261 |     model, to give anyone who possesses the object code either (1) a
262 |     copy of the Corresponding Source for all the software in the
263 |     product that is covered by this License, on a durable physical
264 |     medium customarily used for software interchange, for a price no
265 |     more than your reasonable cost of physically performing this
266 |     conveying of source, or (2) access to copy the
267 |     Corresponding Source from a network server at no charge.
268 | 
269 |     c) Convey individual copies of the object code with a copy of the
270 |     written offer to provide the Corresponding Source.  This
271 |     alternative is allowed only occasionally and noncommercially, and
272 |     only if you received the object code with such an offer, in accord
273 |     with subsection 6b.
274 | 
275 |     d) Convey the object code by offering access from a designated
276 |     place (gratis or for a charge), and offer equivalent access to the
277 |     Corresponding Source in the same way through the same place at no
278 |     further charge.  You need not require recipients to copy the
279 |     Corresponding Source along with the object code.  If the place to
280 |     copy the object code is a network server, the Corresponding Source
281 |     may be on a different server (operated by you or a third party)
282 |     that supports equivalent copying facilities, provided you maintain
283 |     clear directions next to the object code saying where to find the
284 |     Corresponding Source.  Regardless of what server hosts the
285 |     Corresponding Source, you remain obligated to ensure that it is
286 |     available for as long as needed to satisfy these requirements.
287 | 
288 |     e) Convey the object code using peer-to-peer transmission, provided
289 |     you inform other peers where the object code and Corresponding
290 |     Source of the work are being offered to the general public at no
291 |     charge under subsection 6d.
292 | 
293 |   A separable portion of the object code, whose source code is excluded
294 | from the Corresponding Source as a System Library, need not be
295 | included in conveying the object code work.
296 | 
297 |   A "User Product" is either (1) a "consumer product", which means any
298 | tangible personal property which is normally used for personal, family,
299 | or household purposes, or (2) anything designed or sold for incorporation
300 | into a dwelling.  In determining whether a product is a consumer product,
301 | doubtful cases shall be resolved in favor of coverage.  For a particular
302 | product received by a particular user, "normally used" refers to a
303 | typical or common use of that class of product, regardless of the status
304 | of the particular user or of the way in which the particular user
305 | actually uses, or expects or is expected to use, the product.  A product
306 | is a consumer product regardless of whether the product has substantial
307 | commercial, industrial or non-consumer uses, unless such uses represent
308 | the only significant mode of use of the product.
309 | 
310 |   "Installation Information" for a User Product means any methods,
311 | procedures, authorization keys, or other information required to install
312 | and execute modified versions of a covered work in that User Product from
313 | a modified version of its Corresponding Source.  The information must
314 | suffice to ensure that the continued functioning of the modified object
315 | code is in no case prevented or interfered with solely because
316 | modification has been made.
317 | 
318 |   If you convey an object code work under this section in, or with, or
319 | specifically for use in, a User Product, and the conveying occurs as
320 | part of a transaction in which the right of possession and use of the
321 | User Product is transferred to the recipient in perpetuity or for a
322 | fixed term (regardless of how the transaction is characterized), the
323 | Corresponding Source conveyed under this section must be accompanied
324 | by the Installation Information.  But this requirement does not apply
325 | if neither you nor any third party retains the ability to install
326 | modified object code on the User Product (for example, the work has
327 | been installed in ROM).
328 | 
329 |   The requirement to provide Installation Information does not include a
330 | requirement to continue to provide support service, warranty, or updates
331 | for a work that has been modified or installed by the recipient, or for
332 | the User Product in which it has been modified or installed.  Access to a
333 | network may be denied when the modification itself materially and
334 | adversely affects the operation of the network or violates the rules and
335 | protocols for communication across the network.
336 | 
337 |   Corresponding Source conveyed, and Installation Information provided,
338 | in accord with this section must be in a format that is publicly
339 | documented (and with an implementation available to the public in
340 | source code form), and must require no special password or key for
341 | unpacking, reading or copying.
342 | 
343 |   7. Additional Terms.
344 | 
345 |   "Additional permissions" are terms that supplement the terms of this
346 | License by making exceptions from one or more of its conditions.
347 | Additional permissions that are applicable to the entire Program shall
348 | be treated as though they were included in this License, to the extent
349 | that they are valid under applicable law.  If additional permissions
350 | apply only to part of the Program, that part may be used separately
351 | under those permissions, but the entire Program remains governed by
352 | this License without regard to the additional permissions.
353 | 
354 |   When you convey a copy of a covered work, you may at your option
355 | remove any additional permissions from that copy, or from any part of
356 | it.  (Additional permissions may be written to require their own
357 | removal in certain cases when you modify the work.)  You may place
358 | additional permissions on material, added by you to a covered work,
359 | for which you have or can give appropriate copyright permission.
360 | 
361 |   Notwithstanding any other provision of this License, for material you
362 | add to a covered work, you may (if authorized by the copyright holders of
363 | that material) supplement the terms of this License with terms:
364 | 
365 |     a) Disclaiming warranty or limiting liability differently from the
366 |     terms of sections 15 and 16 of this License; or
367 | 
368 |     b) Requiring preservation of specified reasonable legal notices or
369 |     author attributions in that material or in the Appropriate Legal
370 |     Notices displayed by works containing it; or
371 | 
372 |     c) Prohibiting misrepresentation of the origin of that material, or
373 |     requiring that modified versions of such material be marked in
374 |     reasonable ways as different from the original version; or
375 | 
376 |     d) Limiting the use for publicity purposes of names of licensors or
377 |     authors of the material; or
378 | 
379 |     e) Declining to grant rights under trademark law for use of some
380 |     trade names, trademarks, or service marks; or
381 | 
382 |     f) Requiring indemnification of licensors and authors of that
383 |     material by anyone who conveys the material (or modified versions of
384 |     it) with contractual assumptions of liability to the recipient, for
385 |     any liability that these contractual assumptions directly impose on
386 |     those licensors and authors.
387 | 
388 |   All other non-permissive additional terms are considered "further
389 | restrictions" within the meaning of section 10.  If the Program as you
390 | received it, or any part of it, contains a notice stating that it is
391 | governed by this License along with a term that is a further
392 | restriction, you may remove that term.  If a license document contains
393 | a further restriction but permits relicensing or conveying under this
394 | License, you may add to a covered work material governed by the terms
395 | of that license document, provided that the further restriction does
396 | not survive such relicensing or conveying.
397 | 
398 |   If you add terms to a covered work in accord with this section, you
399 | must place, in the relevant source files, a statement of the
400 | additional terms that apply to those files, or a notice indicating
401 | where to find the applicable terms.
402 | 
403 |   Additional terms, permissive or non-permissive, may be stated in the
404 | form of a separately written license, or stated as exceptions;
405 | the above requirements apply either way.
406 | 
407 |   8. Termination.
408 | 
409 |   You may not propagate or modify a covered work except as expressly
410 | provided under this License.  Any attempt otherwise to propagate or
411 | modify it is void, and will automatically terminate your rights under
412 | this License (including any patent licenses granted under the third
413 | paragraph of section 11).
414 | 
415 |   However, if you cease all violation of this License, then your
416 | license from a particular copyright holder is reinstated (a)
417 | provisionally, unless and until the copyright holder explicitly and
418 | finally terminates your license, and (b) permanently, if the copyright
419 | holder fails to notify you of the violation by some reasonable means
420 | prior to 60 days after the cessation.
421 | 
422 |   Moreover, your license from a particular copyright holder is
423 | reinstated permanently if the copyright holder notifies you of the
424 | violation by some reasonable means, this is the first time you have
425 | received notice of violation of this License (for any work) from that
426 | copyright holder, and you cure the violation prior to 30 days after
427 | your receipt of the notice.
428 | 
429 |   Termination of your rights under this section does not terminate the
430 | licenses of parties who have received copies or rights from you under
431 | this License.  If your rights have been terminated and not permanently
432 | reinstated, you do not qualify to receive new licenses for the same
433 | material under section 10.
434 | 
435 |   9. Acceptance Not Required for Having Copies.
436 | 
437 |   You are not required to accept this License in order to receive or
438 | run a copy of the Program.  Ancillary propagation of a covered work
439 | occurring solely as a consequence of using peer-to-peer transmission
440 | to receive a copy likewise does not require acceptance.  However,
441 | nothing other than this License grants you permission to propagate or
442 | modify any covered work.  These actions infringe copyright if you do
443 | not accept this License.  Therefore, by modifying or propagating a
444 | covered work, you indicate your acceptance of this License to do so.
445 | 
446 |   10. Automatic Licensing of Downstream Recipients.
447 | 
448 |   Each time you convey a covered work, the recipient automatically
449 | receives a license from the original licensors, to run, modify and
450 | propagate that work, subject to this License.  You are not responsible
451 | for enforcing compliance by third parties with this License.
452 | 
453 |   An "entity transaction" is a transaction transferring control of an
454 | organization, or substantially all assets of one, or subdividing an
455 | organization, or merging organizations.  If propagation of a covered
456 | work results from an entity transaction, each party to that
457 | transaction who receives a copy of the work also receives whatever
458 | licenses to the work the party's predecessor in interest had or could
459 | give under the previous paragraph, plus a right to possession of the
460 | Corresponding Source of the work from the predecessor in interest, if
461 | the predecessor has it or can get it with reasonable efforts.
462 | 
463 |   You may not impose any further restrictions on the exercise of the
464 | rights granted or affirmed under this License.  For example, you may
465 | not impose a license fee, royalty, or other charge for exercise of
466 | rights granted under this License, and you may not initiate litigation
467 | (including a cross-claim or counterclaim in a lawsuit) alleging that
468 | any patent claim is infringed by making, using, selling, offering for
469 | sale, or importing the Program or any portion of it.
470 | 
471 |   11. Patents.
472 | 
473 |   A "contributor" is a copyright holder who authorizes use under this
474 | License of the Program or a work on which the Program is based.  The
475 | work thus licensed is called the contributor's "contributor version".
476 | 
477 |   A contributor's "essential patent claims" are all patent claims
478 | owned or controlled by the contributor, whether already acquired or
479 | hereafter acquired, that would be infringed by some manner, permitted
480 | by this License, of making, using, or selling its contributor version,
481 | but do not include claims that would be infringed only as a
482 | consequence of further modification of the contributor version.  For
483 | purposes of this definition, "control" includes the right to grant
484 | patent sublicenses in a manner consistent with the requirements of
485 | this License.
486 | 
487 |   Each contributor grants you a non-exclusive, worldwide, royalty-free
488 | patent license under the contributor's essential patent claims, to
489 | make, use, sell, offer for sale, import and otherwise run, modify and
490 | propagate the contents of its contributor version.
491 | 
492 |   In the following three paragraphs, a "patent license" is any express
493 | agreement or commitment, however denominated, not to enforce a patent
494 | (such as an express permission to practice a patent or covenant not to
495 | sue for patent infringement).  To "grant" such a patent license to a
496 | party means to make such an agreement or commitment not to enforce a
497 | patent against the party.
498 | 
499 |   If you convey a covered work, knowingly relying on a patent license,
500 | and the Corresponding Source of the work is not available for anyone
501 | to copy, free of charge and under the terms of this License, through a
502 | publicly available network server or other readily accessible means,
503 | then you must either (1) cause the Corresponding Source to be so
504 | available, or (2) arrange to deprive yourself of the benefit of the
505 | patent license for this particular work, or (3) arrange, in a manner
506 | consistent with the requirements of this License, to extend the patent
507 | license to downstream recipients.  "Knowingly relying" means you have
508 | actual knowledge that, but for the patent license, your conveying the
509 | covered work in a country, or your recipient's use of the covered work
510 | in a country, would infringe one or more identifiable patents in that
511 | country that you have reason to believe are valid.
512 | 
513 |   If, pursuant to or in connection with a single transaction or
514 | arrangement, you convey, or propagate by procuring conveyance of, a
515 | covered work, and grant a patent license to some of the parties
516 | receiving the covered work authorizing them to use, propagate, modify
517 | or convey a specific copy of the covered work, then the patent license
518 | you grant is automatically extended to all recipients of the covered
519 | work and works based on it.
520 | 
521 |   A patent license is "discriminatory" if it does not include within
522 | the scope of its coverage, prohibits the exercise of, or is
523 | conditioned on the non-exercise of one or more of the rights that are
524 | specifically granted under this License.  You may not convey a covered
525 | work if you are a party to an arrangement with a third party that is
526 | in the business of distributing software, under which you make payment
527 | to the third party based on the extent of your activity of conveying
528 | the work, and under which the third party grants, to any of the
529 | parties who would receive the covered work from you, a discriminatory
530 | patent license (a) in connection with copies of the covered work
531 | conveyed by you (or copies made from those copies), or (b) primarily
532 | for and in connection with specific products or compilations that
533 | contain the covered work, unless you entered into that arrangement,
534 | or that patent license was granted, prior to 28 March 2007.
535 | 
536 |   Nothing in this License shall be construed as excluding or limiting
537 | any implied license or other defenses to infringement that may
538 | otherwise be available to you under applicable patent law.
539 | 
540 |   12. No Surrender of Others' Freedom.
541 | 
542 |   If conditions are imposed on you (whether by court order, agreement or
543 | otherwise) that contradict the conditions of this License, they do not
544 | excuse you from the conditions of this License.  If you cannot convey a
545 | covered work so as to satisfy simultaneously your obligations under this
546 | License and any other pertinent obligations, then as a consequence you may
547 | not convey it at all.  For example, if you agree to terms that obligate you
548 | to collect a royalty for further conveying from those to whom you convey
549 | the Program, the only way you could satisfy both those terms and this
550 | License would be to refrain entirely from conveying the Program.
551 | 
552 |   13. Use with the GNU Affero General Public License.
553 | 
554 |   Notwithstanding any other provision of this License, you have
555 | permission to link or combine any covered work with a work licensed
556 | under version 3 of the GNU Affero General Public License into a single
557 | combined work, and to convey the resulting work.  The terms of this
558 | License will continue to apply to the part which is the covered work,
559 | but the special requirements of the GNU Affero General Public License,
560 | section 13, concerning interaction through a network will apply to the
561 | combination as such.
562 | 
563 |   14. Revised Versions of this License.
564 | 
565 |   The Free Software Foundation may publish revised and/or new versions of
566 | the GNU General Public License from time to time.  Such new versions will
567 | be similar in spirit to the present version, but may differ in detail to
568 | address new problems or concerns.
569 | 
570 |   Each version is given a distinguishing version number.  If the
571 | Program specifies that a certain numbered version of the GNU General
572 | Public License "or any later version" applies to it, you have the
573 | option of following the terms and conditions either of that numbered
574 | version or of any later version published by the Free Software
575 | Foundation.  If the Program does not specify a version number of the
576 | GNU General Public License, you may choose any version ever published
577 | by the Free Software Foundation.
578 | 
579 |   If the Program specifies that a proxy can decide which future
580 | versions of the GNU General Public License can be used, that proxy's
581 | public statement of acceptance of a version permanently authorizes you
582 | to choose that version for the Program.
583 | 
584 |   Later license versions may give you additional or different
585 | permissions.  However, no additional obligations are imposed on any
586 | author or copyright holder as a result of your choosing to follow a
587 | later version.
588 | 
589 |   15. Disclaimer of Warranty.
590 | 
591 |   THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
592 | APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
593 | HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
594 | OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
595 | THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
596 | PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
597 | IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
598 | ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
599 | 
600 |   16. Limitation of Liability.
601 | 
602 |   IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
603 | WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
604 | THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
605 | GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
606 | USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
607 | DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
608 | PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
609 | EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
610 | SUCH DAMAGES.
611 | 
612 |   17. Interpretation of Sections 15 and 16.
613 | 
614 |   If the disclaimer of warranty and limitation of liability provided
615 | above cannot be given local legal effect according to their terms,
616 | reviewing courts shall apply local law that most closely approximates
617 | an absolute waiver of all civil liability in connection with the
618 | Program, unless a warranty or assumption of liability accompanies a
619 | copy of the Program in return for a fee.
620 | 
621 |                      END OF TERMS AND CONDITIONS
622 | 
623 |             How to Apply These Terms to Your New Programs
624 | 
625 |   If you develop a new program, and you want it to be of the greatest
626 | possible use to the public, the best way to achieve this is to make it
627 | free software which everyone can redistribute and change under these terms.
628 | 
629 |   To do so, attach the following notices to the program.  It is safest
630 | to attach them to the start of each source file to most effectively
631 | state the exclusion of warranty; and each file should have at least
632 | the "copyright" line and a pointer to where the full notice is found.
633 | 
634 |     <one line to give the program's name and a brief idea of what it does.>
635 |     Copyright (C) <year>  <name of author>
636 | 
637 |     This program is free software: you can redistribute it and/or modify
638 |     it under the terms of the GNU General Public License as published by
639 |     the Free Software Foundation, either version 3 of the License, or
640 |     (at your option) any later version.
641 | 
642 |     This program is distributed in the hope that it will be useful,
643 |     but WITHOUT ANY WARRANTY; without even the implied warranty of
644 |     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
645 |     GNU General Public License for more details.
646 | 
647 |     You should have received a copy of the GNU General Public License
648 |     along with this program.  If not, see <https://www.gnu.org/licenses/>.
649 | 
650 | Also add information on how to contact you by electronic and paper mail.
651 | 
652 |   If the program does terminal interaction, make it output a short
653 | notice like this when it starts in an interactive mode:
654 | 
655 |     <program>  Copyright (C) <year>  <name of author>
656 |     This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
657 |     This is free software, and you are welcome to redistribute it
658 |     under certain conditions; type `show c' for details.
659 | 
660 | The hypothetical commands `show w' and `show c' should show the appropriate
661 | parts of the General Public License.  Of course, your program's commands
662 | might be different; for a GUI interface, you would use an "about box".
663 | 
664 |   You should also get your employer (if you work as a programmer) or school,
665 | if any, to sign a "copyright disclaimer" for the program, if necessary.
666 | For more information on this, and how to apply and follow the GNU GPL, see
667 | <https://www.gnu.org/licenses/>.
668 | 
669 |   The GNU General Public License does not permit incorporating your program
670 | into proprietary programs.  If your program is a subroutine library, you
671 | may consider it more useful to permit linking proprietary applications with
672 | the library.  If this is what you want to do, use the GNU Lesser General
673 | Public License instead of this License.  But first, please read
674 | <https://www.gnu.org/licenses/why-not-lgpl.html>.
675 | 


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