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Truepolyglot is polyglot file generator project. It means 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 the 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 boring to build, even more if you want to respect the file format correctly.
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 the PDF part POC
Polyglot file checked without warning with pdftocairo >= 1.0
Polyglot file checked without warning with caradoc >= 1.0
Rebuild the PDF Xref Table >= 1.0
Stream object with the correct length header value >= 1.0
Add the format β€œzippdf”, file without offset after the Zip data >= 1.1
Polyglot file keeps the original PDF version >= 1.1.1
Add the β€œszippdf” format without offset before and after the Zip data >= 1.2
Fix /Length stream object value and the PDF offset for the szippdf format >= 1.2.1
PDF object numbers reorder after insertion >= 1.3
Add the format β€œpdfany” a valid PDF with custom payload content in the first and the last objet >= 1.5.2
Add β€œacrobat-compatibility” option to allow szippdf to be read with Acrobat Reader (thanks Ange Albertini) >= 1.5.3
Add the format β€œzipany” a valid ZIP with custom payload content at the 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.zip (scan virustotal.com) pdfzip polyglot.pdf (scan virustotal.com) PDF/ZIP polyglot with the 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 the first object or/and payload2 file content as the last object.
* zipany: Generate a valid ZIP file with payload1 file content at the start of the 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 the start for Acrobat Reader compatibility with the szippdf format       
--verbose {none,error,info,debug} Verbosity level  (default: info)

TruePolyglot v1.6.2

Code

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

or download truepolyglot-1.6.2.tar.gz

How to detect a polyglot file ?

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

Contact

[email protected]

Credits

Copyright Β© 2018-2019 [email protected]

TruePolyglot is released under Unlicence except for the following libraries: