├── LICENSE
├── README.md
├── hello_world.b
├── hello_world.m
├── m2elf.pl
└── spawnshell.m
/LICENSE:
--------------------------------------------------------------------------------
1 | GNU GENERAL PUBLIC LICENSE
2 | Version 2, June 1991
3 |
4 | Copyright (C) 1989, 1991 Free Software Foundation, Inc.,
5 | 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
6 | Everyone is permitted to copy and distribute verbatim copies
7 | of this license document, but changing it is not allowed.
8 |
9 | Preamble
10 |
11 | The licenses for most software are designed to take away your
12 | freedom to share and change it. By contrast, the GNU General Public
13 | License is intended to guarantee your freedom to share and change free
14 | software--to make sure the software is free for all its users. This
15 | General Public License applies to most of the Free Software
16 | Foundation's software and to any other program whose authors commit to
17 | using it. (Some other Free Software Foundation software is covered by
18 | the GNU Lesser General Public License instead.) You can apply it to
19 | your programs, too.
20 |
21 | When we speak of free software, we are referring to freedom, not
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30 | These restrictions translate to certain responsibilities for you if you
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32 |
33 | For example, if you distribute copies of such a program, whether
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35 | you have. You must make sure that they, too, receive or can get the
36 | source code. And you must show them these terms so they know their
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39 | We protect your rights with two steps: (1) copyright the software, and
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41 | distribute and/or modify the software.
42 |
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56 | The precise terms and conditions for copying, distribution and
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58 |
59 | GNU GENERAL PUBLIC LICENSE
60 | TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
61 |
62 | 0. This License applies to any program or other work which contains
63 | a notice placed by the copyright holder saying it may be distributed
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71 |
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77 | Whether that is true depends on what the Program does.
78 |
79 | 1. You may copy and distribute verbatim copies of the Program's
80 | source code as you receive it, in any medium, provided that you
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85 | along with the Program.
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257 |
258 | NO WARRANTY
259 |
260 | 11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
261 | FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
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268 | REPAIR OR CORRECTION.
269 |
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279 |
280 | END OF TERMS AND CONDITIONS
281 |
282 | How to Apply These Terms to Your New Programs
283 |
284 | If you develop a new program, and you want it to be of the greatest
285 | possible use to the public, the best way to achieve this is to make it
286 | free software which everyone can redistribute and change under these terms.
287 |
288 | To do so, attach the following notices to the program. It is safest
289 | to attach them to the start of each source file to most effectively
290 | convey the exclusion of warranty; and each file should have at least
291 | the "copyright" line and a pointer to where the full notice is found.
292 |
293 | {description}
294 | Copyright (C) {year} {fullname}
295 |
296 | This program is free software; you can redistribute it and/or modify
297 | it under the terms of the GNU General Public License as published by
298 | the Free Software Foundation; either version 2 of the License, or
299 | (at your option) any later version.
300 |
301 | This program is distributed in the hope that it will be useful,
302 | but WITHOUT ANY WARRANTY; without even the implied warranty of
303 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
304 | GNU General Public License for more details.
305 |
306 | You should have received a copy of the GNU General Public License along
307 | with this program; if not, write to the Free Software Foundation, Inc.,
308 | 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
309 |
310 | Also add information on how to contact you by electronic and paper mail.
311 |
312 | If the program is interactive, make it output a short notice like this
313 | when it starts in an interactive mode:
314 |
315 | Gnomovision version 69, Copyright (C) year name of author
316 | Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
317 | This is free software, and you are welcome to redistribute it
318 | under certain conditions; type `show c' for details.
319 |
320 | The hypothetical commands `show w' and `show c' should show the appropriate
321 | parts of the General Public License. Of course, the commands you use may
322 | be called something other than `show w' and `show c'; they could even be
323 | mouse-clicks or menu items--whatever suits your program.
324 |
325 | You should also get your employer (if you work as a programmer) or your
326 | school, if any, to sign a "copyright disclaimer" for the program, if
327 | necessary. Here is a sample; alter the names:
328 |
329 | Yoyodyne, Inc., hereby disclaims all copyright interest in the program
330 | `Gnomovision' (which makes passes at compilers) written by James Hacker.
331 |
332 | {signature of Ty Coon}, 1 April 1989
333 | Ty Coon, President of Vice
334 |
335 | This General Public License does not permit incorporating your program into
336 | proprietary programs. If your program is a subroutine library, you may
337 | consider it more useful to permit linking proprietary applications with the
338 | library. If this is what you want to do, use the GNU Lesser General
339 | Public License instead of this License.
340 |
--------------------------------------------------------------------------------
/README.md:
--------------------------------------------------------------------------------
1 | m2elf
2 | =====
3 |
4 | Converts Machine Code to x86 (32-bit) Linux executable (auto-wrapping with ELF headers). This script comes included in Remnux v6
5 |
6 | Command Usage
7 | =====
8 | Options:
9 | --in (input file)
10 | --out (output file)
11 | --binary (if the input is already binary form)
12 | --mem (bytes)
13 | --entry (This changes the entry point, it adds to the offset whichever decimal number is provided)
14 | --writeover - changes the r-x of the .text to rwx; now you can have self modifying codes
15 |
16 | m2elf --in source_file.m --out executable_file --mem 100
17 |
18 | Example Source Files
19 | =====
20 | * hello.m - written in machine code, prints hello world. Use --mem 16
21 | * hello.b - same as above, but written in pure 1's and 0's :)
22 | * Spawnshell.m - shellcode from: http://phrack.org/issues/49/14.html#article, the difference with this .m file is that each instruction is commented. To get this to actually run, the --writeover argument must be used.
23 |
24 | Source File Syntax
25 | =====
26 | The source file can include ascii hex and binary byte by byte. Spacing between hex bytes not a requirment, but could reduce bugs (4 hex bytes could look like binary to m2elf if the hex is only 1's and 0's). In order for a binary byte to be interpreted as such, it needs to be a series of 8 1's and 0's preceded by an underscore, i.e. _01011000
27 |
28 | Valid comments include #, //, ', and --
29 |
--------------------------------------------------------------------------------
/hello_world.b:
--------------------------------------------------------------------------------
1 |
2 | _10111000 _00100001 _00001010 _00000000 _00000000
3 | _10100011 _00001100 _00010000 _00000000 _00000110
4 | _10111000 _01101111 _01110010 _01101100 _01100100
5 | _10100011 _00001000 _00010000 _00000000 _00000110
6 | _10111000 _01101111 _00101100 _00100000 _01010111
7 | _10100011 _00000100 _00010000 _00000000 _00000110
8 | _10111000 _01001000 _01100101 _01101100 _01101100
9 | _10100011 _00000000 _00010000 _00000000 _00000110
10 | _10111001 _00000000 _00010000 _00000000 _00000110
11 | _10111010 _00010000 _00000000 _00000000 _00000000
12 | _10111011 _00000001 _00000000 _00000000 _00000000
13 | _10111000 _00000100 _00000000 _00000000 _00000000
14 | _11001101 _10000000
15 |
16 | _10111000 _00000001 _00000000 _00000000 _00000000
17 | _11001101 _10000000
18 |
--------------------------------------------------------------------------------
/hello_world.m:
--------------------------------------------------------------------------------
1 | b8 21 0a 00 00 #moving "!\n" into eax
2 | a3 0c 10 00 06 #moving eax into first memory location
3 | b8 6f 72 6c 64 #moving "orld" into eax
4 | a3 08 10 00 06 #moving eax into next memory location
5 | b8 6f 2c 20 57 #moving "o, W" into eax
6 | a3 04 10 00 06 #moving eax into next memory location
7 | b8 48 65 6c 6c #moving "Hell" into eax
8 | a3 00 10 00 06 #moving eax into next memory location
9 |
10 | b9 00 10 00 06 #moving pointer to start of memory location into ecx
11 | ba 10 00 00 00 #moving string size into edx
12 | bb 01 00 00 00 #moving "stdout" number to ebx
13 | b8 04 00 00 00 #moving "print out" syscall number to eax
14 | cd 80 #calling the linux kernel to execute our print to stdout
15 |
16 | b8 01 00 00 00 #moving "sys_exit" call number to eax
17 | cd 80 #executing it via linux sys_call
18 |
--------------------------------------------------------------------------------
/m2elf.pl:
--------------------------------------------------------------------------------
1 | #!/usr/bin/perl
2 | #ELF construction based on reversing done by Ange Albertini from corkami.com (great infographic),
3 | #http://man7.org/linux/man-pages/man5/elf.5.html, and just assembling stuff with nasm and comparing results.
4 | #These files generated may not be 'proper,' but they seem execute pretty well.
5 | use warnings;
6 | use strict;
7 | use Getopt::Long;
8 | use Term::ANSIColor;
9 |
10 | my ($in, $binary, $hex, $code);
11 | my $out = "out";
12 | my $temp_data;
13 | my $memory_size = 0;
14 | my $entry = 0;
15 | my $writeover = 0;
16 | my $help = 0;
17 | my $interactive = 0;
18 | my $flavor = "intel";
19 | my $colorize = 0;
20 |
21 | sub colorize($);
22 |
23 | GetOptions('in=s' => \$in,
24 | 'out=s' => \$out,
25 | 'binary' => \$binary,
26 | 'mem=s' => \$memory_size,
27 | 'entry=s' => \$entry,
28 | 'writeover' => \$writeover,
29 | 'interactive' => \$interactive,
30 | 'flavor=s' => \$flavor,
31 | 'colorize' => \$colorize,
32 | 'help' => \$help);
33 |
34 | if ($help eq 1){
35 | help();
36 | }
37 |
38 | if ($interactive eq 1){
39 | my $result;
40 | qx{which objdump 2>&1};
41 | if ($? > 0) {
42 | print "This system needs 'objdump' installed in order to run 'interactive' mode\n";
43 | } else {
44 | $code = '';
45 | $out = 'tmp';
46 | while (1) {
47 | print "m2elf > ";
48 | $code = ;
49 | next if ($code =~ /^$/);
50 | last if ($code =~ /(exit|q(?:uit)*)/i);
51 | convert();
52 | payload();
53 | $result = `objdump -M $flavor -d tmp`;
54 | $result =~ s/^.+?<>:\n(.+)\s\.\.\..+$/$1/s;
55 | if ($colorize) {
56 | print colorize($result), "\n";
57 | } else {
58 | print "$result\n";
59 | }
60 | }
61 | system('rm tmp')
62 | }
63 | }
64 |
65 | #--------------------------Code/Strings/Sections------------------------------------
66 | if ($in) {
67 |
68 | $/ = undef;
69 | open IN, "$in" or die "Couldn't open $in, $!\n";
70 | $code = ;
71 | $/ = "\n";
72 |
73 | if ($binary) {
74 | } else {
75 | convert();
76 | }
77 | } else {
78 | $code = "\x90\x90\x90\x90\x90\x90\xb8\x01\x00\x00\x00\xcd\x80";
79 | }
80 |
81 | sub payload {
82 |
83 | #Fix padding of code; pad code to be divisible by 16 bytes
84 | $code .= "\x00" x (16 - (length($code) % 16)) if ((length($code) % 16) != 0);
85 |
86 | #Section Names
87 | my $shstrtab_name = "\x00\x2e\x73\x68\x73\x74\x72\x74\x61\x62\x00"; #null record followed by ".shstrtab"
88 | my $text_name = "\x2e\x74\x65\x78\x74\x00"; #".text"
89 | my $bss_name = ''; #Does not exist unless --mem is declared with a value
90 | my $section_names = ''; #just an init of our section names header
91 | if ($memory_size > 0) { #If allocating memory
92 | $bss_name = "\x2e\x62\x73\x73\x00"; #".bss"
93 | $section_names = $shstrtab_name . $text_name . $bss_name . ("\x00" x 10); #section names is null+.shstrtab+.text+.bss+10bytes_padding
94 | } else { #Otherwise, build without .bss
95 | $section_names = $shstrtab_name . $text_name . ("\x00" x 15); #So null+.shstrtab+.text and pad 15 bytes
96 | }
97 |
98 |
99 | #Section Header Table
100 | #Null Section
101 | my $null = "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00";
102 |
103 | #Text Section
104 | #name at offset 0b, type 01, flags 0x06 (allocated & executable), start at addr 0x8000060 / offset 0x60
105 | my $text = "\x0b\x00\x00\x00\x01\x00\x00\x00\x06\x00\x00\x00\x60\x00\x00\x08\x60\x00\x00\x00";
106 | if ($memory_size > 0) { #if we allocated memory, change the start at addr to 0x8000080 / offset 0x80
107 | $text = "\x0b\x00\x00\x00\x01\x00\x00\x00\x06\x00\x00\x00\x80\x00\x00\x08\x80\x00\x00\x00";
108 | }
109 | my $offset = printhex_32(length($code)); #get length of padded code and represent as intel-endian 4-byte structure
110 | #concatenate headers so far, possible different offset due to memory alloc, structured size, and pretty much null-pad out
111 | $text .= $offset . "\x00\x00\x00\x00\x00\x00\x00\x00\x10\x00\x00\x00\x00\x00\x00\x00";
112 |
113 | #Section Names section, but I'll just call this Shitter Tab.
114 | my $shrtrtab = ''; #init
115 | my $bss_header = ''; #init
116 | my $sections = ''; #init
117 | if ($memory_size > 0) { #if there's memory,
118 | #BSS Header now...
119 | $bss_header = "\x11\x00\x00\x00" . "\x08\x00\x00\x00" . "\x03\x00\x00\x00"; #name header starts at 0x11, type 8, flag 3
120 | $offset = printhex_32(100663296); #0x06000000
121 | $bss_header .= $offset; #add the start addr
122 | $offset = printhex_32(4096); #offset 0x1000
123 | $bss_header .= $offset; #add the offset
124 | $offset = printhex_32($memory_size); #add intel-endian bytes for size of bss section
125 | #Finally, null pad this header out
126 | $bss_header .= $offset . "\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00\x00\x00\x00\x00\x00\x00";
127 |
128 | #Now to proceed with the Shitter Tab
129 | #name offset starts at 0x01, it's type 3 (string table), no flags (null), no addr
130 | $shrtrtab = "\x01\x00\x00\x00\x03\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00";
131 | $offset = printhex_32(128 + length($code)); #intel-endian offset + 0x80
132 | #size is always 0x19 bytes, then null-pad out
133 | $shrtrtab .= $offset . "\x19\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00";
134 |
135 | #Glue the .bss version of section header table together
136 | $sections = $null . $text . $bss_header . $shrtrtab;
137 | } else {
138 | #Without .bss, the shitter table has an offset of 0xa0
139 | $shrtrtab = "\x01\x00\x00\x00\x03\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xa0\x00\x00\x00\x19\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00";
140 | #Glue the non .bss version of the section header table together
141 | $sections = $null . $text . $shrtrtab;
142 | }
143 |
144 |
145 | #--------------------------Program Header Table setup------------------------------
146 | #This is all for the .text segment
147 | my $p_type = "\x01\x00\x00\x00"; #The segment should be loaded into memory
148 | my $p_offset = "\x00\x00\x00\x00"; #Offset where it should be read
149 | my $p_addr = "\x00\x00\x00\x08"; #Virtual address where it should be loaded
150 | my $p_paddr = "\x00\x00\x00\x08"; #Physical address where it should be loaded
151 | my $p_flags = "\x05\x00\x00\x00"; #Readable and eXecutable (by default)
152 |
153 | #If we LOVE self modifying code, put your hands up!
154 | if ($writeover eq 1) {
155 | $p_flags = "\x06\x00\x00\x00";
156 | }
157 |
158 | #Give a little extra mem for now, until I actually try and figure this out, but I don't care
159 | my $p_filesz = printhex_32(length($code) + 160); #Size on file
160 | my $p_memsz = $p_filesz; #Size in memory
161 |
162 | #Build the header up
163 | my $program_header_table = $p_type . $p_offset . $p_addr . $p_paddr . $p_filesz . $p_memsz . $p_flags . "\x00\x10\x00\x00";
164 |
165 | #If we want memeory, the below code builds up the .bss segment
166 | if ($memory_size > 0) {
167 | #Similar headers as .text, but starts at 0x6000000, and flags are rwx by default on this one
168 | $program_header_table .= "\x01\x00\x00\x00\x00\x00\x00\x00\x00\x10\x00\x06\x00\x10\x00\x06";
169 | $program_header_table .= printhex_32($memory_size) . printhex_32($memory_size);
170 | $program_header_table .= "\x06\x00\x00\x00\x00\x10\x00\x00";
171 | }
172 |
173 | #--------------------------ELF Header setup---------------------------------------
174 |
175 | my $e_ident_EI_MAG = "\x7f\x45\x4c\x46"; #constant signature (ELF)
176 | my $e_ident_EI_CLASS_DATA = "\x01\x01"; #32 bits, Little-Endian
177 | my $e_ident_EI_VERSION = "\x01\x00\x00\x00"; #Always 1
178 | my $e_type = "\x02\x00"; #Executable
179 | my $e_machine = "\x03\x00"; #Intel 386 (and later)
180 | my $e_version = "\x01\x00\x00\x00"; #Always 1
181 | my $e_entry = "\x60\x00\x00\x08"; #Entry Point
182 | my $e_phoff = "\x40\x00\x00\x00"; #Program Headers' offset
183 | my $e_shoff = "\x00\x00\x00\x00"; #Section Header's offset, 0'd out for now, calculated later
184 | my $e_ehsize = "\x34\x00"; #ELF header's size
185 | my $e_phentsize = "\x20\x00"; #Size of a single Program Header
186 | my $e_phnum = "\x01\x00"; #Count of Program Headers
187 | my $e_shentsize = "\x28\x00"; #Size of a single Section Header (probably static)
188 | my $e_shnum = "\x03\x00"; #Count of Section Headers
189 | my $e_shstrndx = "\x02\x00"; #Index of the names' section in the table
190 | #A few values need changing if we allocate memory with .bss segment (offsets and stuff)
191 | if ($memory_size > 0) {
192 | $e_shnum = "\x04\x00";
193 | $e_shstrndx = "\x03\x00";
194 | $e_phnum = "\x02\x00";
195 | $e_entry = "\x80\x00\x00\x08";
196 | }
197 |
198 | #Change entry point if user wants this, it is not a specific address; it's a number of bytes to add to the current entry offset
199 | if ($entry > 0) {
200 | $entry += 134217824;
201 | $e_entry = printhex_32($entry);
202 | }
203 |
204 | #Calculate e_shoff size (Section Header offset)
205 | $e_shoff = length($code . $section_names) + 96; #section names + code + 96 bytes of fixed size ELF headers
206 | if ($memory_size > 0) {
207 | $e_shoff += 32; #32 bytes of extra header info if we have .bss
208 | }
209 | $e_shoff = printhex_32($e_shoff); #format this number to intel-endian 4-byte value
210 |
211 | #Build ELF Header
212 | my $ELF_header = $e_ident_EI_MAG . $e_ident_EI_CLASS_DATA . $e_ident_EI_VERSION . ("\x00" x 6) . $e_type . $e_machine . $e_version .
213 | $e_entry . $e_phoff . $e_shoff . ("\x00" x 4) . $e_ehsize . $e_phentsize . $e_phnum . $e_shentsize . $e_shnum . $e_shstrndx . ("\x00" x 12);
214 |
215 | #-------------------------combine everything--------------------------------------
216 | my $output = $ELF_header . $program_header_table . $code . $section_names . $sections;
217 |
218 | #write all of this to our file
219 | open FILE, ">$out" or die "Couldn't open $out, $!\n";
220 | print FILE $output; #send it out
221 | close FILE;
222 | chmod(0755, $out) or die "Couldn't change the permission to $out: $!";
223 |
224 | }
225 |
226 | payload();
227 |
228 | #This sub takes an integer and converts it into it's 32-bit intel-endian form
229 | sub printhex_32 {
230 | my $value = shift; #get the value passed to it
231 | my $return; #make a return variable
232 | $value = sprintf("%.8X\n", $value); #get an "ASCII HEX" version of the value
233 | if ($value =~ /(.)(.)(.)(.)(.)(.)(.)(.)/) { #parse out each character
234 | $return = pack("C*", map { $_ ? hex($_) :() } $7.$8) . pack("C*", map { $_ ? hex($_) :() } $5.$6) .
235 | pack("C*", map { $_ ? hex($_) :() } $3.$4) . pack("C*", map { $_ ? hex($_) :() } $1.$2); #unpack it
236 | }
237 | return $return; #return the hex data
238 | }
239 |
240 | sub convert {
241 | my $temp_code = '';
242 | $code =~ s/(.*)(#|\/\/|'|\-\-).*/$1/g; #remove comments
243 | #Find 8-bit binary strings and convert to ascii-hex
244 | while ($code =~ /_([01]{8})[^01]/) {
245 | my $replacement = sprintf('%X', oct("0b$1"));
246 | if (length($replacement) == 1) {
247 | $replacement = "0" . $replacement;
248 | }
249 | $code =~ s/_[01]{8}([^01])/$replacement $1/;
250 | }
251 | $code =~ s/\s//g; #remove spaces
252 |
253 | #Has pure ascii-hex, convert to binary data
254 | while ($code =~ /(..)/) { #Get the matching hex into $1
255 | $temp_code .= pack("C*", map { $_ ? hex($_) :() } $1);
256 | $code =~ s/^..//;
257 | }
258 | $code = $temp_code;
259 | }
260 |
261 | sub colorize($) {
262 | my $code = shift || return undef;
263 | my($addr, $opcode, $inst, $operands) = $code =~ m/^[\s\t]*(\d+)\:[\s\t]+((?:[\da-f]+\s)+)[\s\t]+([a-z]+)\s*(.*)$/gi;
264 | my($green, $yellow, $blue, $red, $reset) = (color('green'), color('yellow'), color('blue'), color('red'), color('reset'));
265 |
266 | return undef unless (defined $addr);
267 | $code =~ s/$addr/$green$addr$reset/;
268 | $code =~ s/$opcode/$yellow$opcode$reset/;
269 | $code =~ s/$inst/$blue$inst$reset/;
270 | if (defined $operands) {
271 | $operands =~ s/([\[\]\(\)+\-*\$])/\\$1/g;
272 | $code =~ s/$operands/$red$operands$reset/;
273 | $code =~ s/\\//g;
274 | }
275 |
276 | return $code;
277 | }
278 |
279 | sub help {
280 | print "NAME\n";
281 | print "\tm2elf - Machine Code to ELF wrapped executable binary\n\n";
282 | print "SYNOPSIS\n";
283 | print "\tm2elf.pl --in inputfile --out outputfile\n\n";
284 | print "DESCRIPTION\n";
285 | print "\tThis script takes ascii-hex, space delimited chunks of 8 1' and 0's, or a binary file as input and crafts an appropriate ELF header to make this machine code executable on Linux (32-bit).\n\n";
286 | print "OPTIONS\n";
287 | print "\t--in: specify your source file after this\n";
288 | print "\t--out: specify the name you want your executable file to be\n";
289 | print "\t--interactive: use interactive mode\n";
290 | print "\t--binary: if your file is raw (binary file with unprintables; already machine code), then supply this option. This option is great for extractions from pcaps\n";
291 | print "\t--mem: specify how many bytes of memory you want after this option, it will map starting at offset 0x06000000\n";
292 | print "\t--entry: you can change the entry point. The default is 0x08000060. Whichever number you specify, will add that amount of bytes to the default offset. It will not shift the beginning of your code to that offset, however. For example, if you supply --entry 16, add 16 NOPs to the begginning of your original code and it will function as if you didn't add the --entry 16 and the NOPs\n";
293 | print "\t--writeover: changes the r-x of the .text to rwx; now you can have self modifying codes\n";
294 | print "\t--flavor: flavor of output, default is 'intel' syntax (man objdump for a list of syntax flavors)\n";
295 | print "\t--colorize: colorize output\n\n";
296 | print "EXAMPLES\n";
297 | print "\tSOURCE:\n";
298 | print "\tb8\t21 0a 00 00\t#moving '!\\n' into eax\n";
299 | print "\ta3\t0c 10 00 06\t#moving eax into first memory location\n";
300 | print "\tb8\t6f 72 6c 64\t#moving 'orld' into eax\n";
301 | print "\ta3\t08 10 00 06\t#moving eax into next memory location\n";
302 | print "\tb8\t6f 2c 20 57\t#moving 'o, W' into eax\n";
303 | print "\ta3\t04 10 00 06\t#moving eax into next memory location\n";
304 | print "\tb8\t48 65 6c 6c\t#moving 'Hell' into eax\n";
305 | print "\ta3\t00 10 00 06\t#moving eax into next memory location\n";
306 | print "\tb9\t00 10 00 06\t#moving pointer to start of memory location into ecx\n";
307 | print "\tba\t10 00 00 00\t#moving string size into edx\n";
308 | print "\tbb\t01 00 00 00\t#moving 'stdout' number to ebx\n";
309 | print "\tb8\t04 00 00 00\t#moving 'print out' syscall number to eax\n";
310 | print "\tcd\t80\t\t#calling the linux kernel to execute our print to stdout\n";
311 | print "\tb8\t01 00 00 00\t#moving 'sys_exit' call number to eax\n";
312 | print "\tcd\t80\t\t#executing it via linux sys_call\n\n";
313 | print "\tAssemble with: m2elf.pl --in inputfile --out outputfile --mem 16\n\n";
314 | exit;
315 | }
316 |
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/spawnshell.m:
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1 | eb 2a #Jump down to The "CALL" op below
2 | 5e #Pop ESI (contains pointer to start of /bin/sh text)
3 | 89 76 08 #mov [esi+8], esi (8 bytes after /bin/sh text holds pointer to beginning of /bin/sh)
4 | c6 46 07 00 #mov [esi+7], 0 (moving 0 into 7 bytes after the /bin/sh [wich null terminates])
5 | c7 46 0c 00 00 00 00 #mov [esi+12,] 0 (zero out some bytes offset 12 from /bin/sh text)
6 | b8 0b 00 00 00 #mov eax, 11 (syscall number for execing stuff)
7 | 89 f3 #mov ebx, esi (ebx is pointer to command to run, esi contains that pointer)
8 | 8d 4e 08 #lea ecx, [esi +8] (value of esi + 8 gets loaded into eax, which is pointing to after /bin/sh)
9 | 8d 56 0c #lea edx, [esi+12] (value of esi + 12 gets loaded into eax, which is pointing to a few bytes after /bin/sh)
10 | cd 80 #actually execute /bin/sh
11 | b8 01 00 00 00 #syscall for exiting program
12 | bb 00 00 00 00 #return value
13 | cd 80 #actually exit
14 | e8 d1 ff ff ff #Call to 2nd instruction, this also indirectly gets the address of the data below onto the stack.
15 | 2f 62 69 6e 2f 73 68 00 89 ec 5d c3 #/bin/sh
16 |
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