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Truepolyglot is polyglot file generator project. This means that the generated file is composed of several file formats. The same file can be opened as a ZIP file and as a PDF file for example. The idea of this project comes from work of Ange Albertini, International Journal of Proof-of-Concept or Get The Fuck Out and Julia Wolf that explain how we can build a polyglot file.
Polyglot file can be fastidious to build, even more if you want to respect correctly file format. That’s why I decided to build a tool to generate them.
My main motivation was the technical challenge.

Features and versions

Description Version
Build a polyglot file valid as PDF and ZIP format and that can be opened with 7Zip and Windows Explorer POC
Add a stream object in PDF part POC
Polyglot file checked without warning with pdftocairo >= 1.0
Polyglot file checked without warning with caradoc >= 1.0
Rebuild PDF Xref Table >= 1.0
Stream object with correct length header value >= 1.0
Format β€œzippdf”, file without offset after Zip data >= 1.1
Polyglot file keep original PDF version >= 1.1.1
Add β€œszippdf” format without offset before and after Zip data >= 1.2
Fix /Length stream object value and PDF offset for szippdf format >= 1.2.1
PDF object numbers reorder after insertion >= 1.3
Format β€œpdfany”, a valid PDF with custom payload content in first and last objet >= 1.5.2
Add β€œacrobat-compatibility” option to allow szippdf to be read with Acrobat Reader >= 1.5.3
Format β€œzipany”, a valid ZIP with custom payload content at start and between LHF and CD >= 1.6

Polyglot file compatibility

Software Formats status
Acrobat Reader pdfzip, zippdf, szippdf, pdfany OK
Sumatra PDF pdfzip, zippdf, szippdf, pdfany OK
Foxit PDF Reader pdfzip, zippdf, szippdf, pdfany OK
Edge pdfzip, zippdf, szippdf, pdfany OK
Firefox pdfzip, zippdf, szippdf, pdfany OK
7zip pdfzip, zippdf, zipany OK with warning
7zip szippdf OK
Explorer Windows pdfzip, zippdf, szippdf, pdfany, zipany OK
Info-ZIP (unzip) pdfzip, zippdf, szippdf, pdfany, zipany OK
Evince pdfzip, zippdf, szippdf, pdfany OK
pdftocairo -pdf pdfzip, zippdf, szippdf, pdfany OK
caradoc stats pdfzip, pdfany OK
java -jar szippdf OK

Examples

First input file Second input file Format Polyglot Comment
doc.pdf archive.zip pdfzip polyglot.pdf PDF/ZIP polyglot - 122 Ko
orwell_1984.pdf file-FILE5_32.zip pdfzip polyglot.pdf PDF/ZIP polyglot - 1.3 Mo
x86asm.pdf fasmw17304.zip pdfzip polyglot.pdf PDF/ZIP polyglot - 1.8 Mo
doc.pdf archive.zip zippdf polyglot.pdf PDF/ZIP polyglot - 112 Ko
electronics.pdf hello_world.jar szippdf polyglot.pdf PDF/JAR polyglot - 778 Ko
hexinator.pdf eicar.zipΒ (scan virustotal.com) pdfzip polyglot.pdfΒ (scan virustotal.com) PDF/ZIP polyglot with Eicar test in Zip - 2.9 Mo
doc.pdf page.html pdfany polyglot.pdf PDF/HTML polyglot - 26 Ko
logo.zip nc.exe zipany polyglot.zip PDF/PE polyglot - 96 Ko

Usage

usage: truepolyglot format [options] output-file

Generate a polyglot file.

Formats availables:
* pdfzip: Generate a file valid as PDF and ZIP. The format is closest to PDF.
* zippdf: Generate a file valid as ZIP and PDF. The format is closest to ZIP.
* szippdf: Generate a file valid as ZIP and PDF. The format is strictly a ZIP.
           Archive is modified.
* pdfany: Generate a valid PDF file with payload1 file content as first object
          or/and payload2 file content as last oject.
* zipany: Generate a valid ZIP file with payload1 file content at start of file
          or/and payload2 file content between LFH and CD.

positional arguments:
  {pdfzip,zippdf,szippdf,pdfany,zipany}
                        Output polyglot format
  output_file           Output polyglot file path

optional arguments:
  -h, --help            show this help message and exit
  --pdffile PDFFILE     PDF input file
  --zipfile ZIPFILE     ZIP input file
  --payload1file PAYLOAD1FILE
                        Payload 1 input file
  --payload2file PAYLOAD2FILE
                        Payload 2 input file
  --acrobat-compatibility
                        Add a byte at start for Acrobat Reader compatibility with szippdf format
  --verbose {none,error,info,debug}
                        Verbosity level  (default: info)

TruePolyglot v1.6.1

Code

git clone https://git.hackade.org/truepolyglot.git/

or download truepolyglot-1.6.1.tar.gz

How to detect polyglot file ?

You can use binwalk on a file to see if composed of multiple files.

Contact

[email protected]