Awesome

PDF Analysis

Several PDF analysis has already been done, I reassembled a lot of them with additional tips & tools here

• PDF format<br />
• Tools list<br />
• Quick Analysis<br />
• Complete Analysis<br />
  • Basic informations<br />
  • Metadata<br />
  • Search for older version<br />
  • Online Analysis<br />
  • Statistics<br />
  • Visual analysis<br />
  • Go deeper in the analysis<br />
  • Displaying objects and actions structure<br />
  • Map of the objects flows<br />
  • Actions<br />
  • Compression<br />
  • Embeded files<br />
  • Extract files / scripts / objects<br />
  • Conversions<br />
  • Encryption<br />
  • Javascript<br />
  • Flash<br />
• Sources<br />

PDF Format :page_facing_up:

Tools list :wrench:

Existing list

http://blog.didierstevens.com/programs/pdf-tools/ <br /> https://github.com/sans-dfir/sift-files/tree/master/pdf-tools

Quick Analysis :rocket:

Basic informations

$ file file.pdf
$ pdfinfo -box -meta -js -rawdates file.pdf

Displaying objects and actions structure

$ python pdfdid.py -aefv file.pdf

Search for /OpenAction /AA /Launch /GoTo /GoToR /SubmitForm /Richmedia (for Flash) /JS /JavaScript /URI - Encode - Cipher - Shell code - Obfuscation...

Automatically with ParanoiDF

$ python paranoiDF.py -fl file.pdf

Or with pdf-parser

$ python pdf-parser.py -v file.pdf

With an hexadecimal analyser

$ bless file.pdf

Extract files / scripts / Objects

pdf-parser to extract a js object for example

$ pdf-parser --object 32 --raw > extractedObject.js

pdfextract from Origami

$ pdfextract file.pdf

Online analysis<br />

Beware to don't leak any important/professional/personnal data or to expose your research<br /> https://www.hybrid-analysis.com/

Complete Analysis :mag_right:

Basic informations

$ file file.pdf
$ pdfinfo file.pdf
$ pdfinfo -box -meta -js -rawdates file.pdf

Powerfull Python tool to analyze PDF and exploit

$ pyew file.pdf 	

Other Python tool to explore PDF

$ peepdf -fl file.pdf
$ peepdf --interactive file.pdf

Analysis under Windows

PDF Stream Dumper<br /> https://github.com/dzzie/pdfstreamdumper

Metadata

Get metadata

$ exiftool -a -u -g2 file.pdf

Get metadata recursivly from current directory

$ exiftool -r -ext pdf .

Change an element

$ exiftool -Title="New title" file.pdf

Remove metadata

$ exiftool -all= file.pdf && exiftool -all:all= file.pdf && qpdf --linearize file.pdf filewithoutmeta.pdf
$ mat file.pdf # latest version of mat doesn't support pdf format anymore...

Remove metadata recursively from the current directory : Very dirty but work well The filename must not have space at the moment, the commande will be optimized

$ find . -name "*.pdf" -print0 | while read -d $'\0' file; do echo ${file:2} && mv ${file:2} ${file:2}.pdf && exiftool -all= ${file:2}.pdf && exiftool -all:all= ${file:2}.pdf && qpdf --linearize ${file:2}.pdf ${file:2} && rm ${file:2}.pdf && rm ${file:2}.pdf_original; done

Search for older versions

Search for older "hidden" versions

$ pdfresurrect file.pdf -i
$ exiftool -pdf-update:all= file.pdf

Online Analysis

Statistics

Calcul byte statistics, entropy min and max, ASCII count, ... from a PDF

$ python byte-stats.py file.pdf

Visual analysis

Visual analysis of a PDF or a binary file<br /> http://binvis.io

Go deeper in the analysis

Displaying objects and actions structure

$ python pdfid.py --all --extra --force --verbose file.pdf

Map of the objects flows

$ pdf-parser file.pdf | ./pdfobjflow
$ eog pdfobjflow.png

Actions

Search for : <br /> /OpenAction /AA specifies the script or action to run automatically.<br /> /Names /AcroForm /Action can also specify and launch scripts or actions.<br /> /JavaScript specifies JavaScript to run.<br /> /GoTo changes the view to a specified destination within the PDF or in another PDF file.<br /> /Launch a program or opens a document.<br /> /URI accesses a resource by its URL.<br /> /SubmitForm /GoToR can send data to URL.<br /> /RichMedia can be used to embed Flash in PDF.<br /> /ObjStm can hide objects inside an Object Stream.<br /> /JavaScript > /J#61vaScript Beware on obfuscation technique with hex codes

With ParanoiDF

$ python paranoiDF.py -fl file.pdf

With pdf-parser

$ python pdf-parser.py -v file.pdf

With an hexadecimal analyser

$ bless file.pdf

With dumppdf

$ dumppdf -a file.pdf

Compression

Search for compression

$ strings file.pdf | grep --color "/Filter"

2 ways to decompress a PDF

$ pdftk compressed.pdf output uncompressed.pdf uncompress
$ qpdf --stream-data=uncompress compressed.pdf uncompressed.pdf 

Embeded files

4 ways to search for embeded files/scripts inside a PDF

$ binwalk file.pdf
$ foremost -a -v file.pdf
$ hachoir-subfile file.pdf
$ scalpel file.pdf

Extract files / scripts / objects

Extract file corresponding to object ID, jpg for example

$ dumppdf.py -i 32 -r file.pdf > image.jpg

Extract js from an object for example

$ pdf-parser --object 32 --raw > extractedObject.js

pdfextract from Origami

$ pdfextract file.pdf

Conversion

PDF to Postscript

$ pdftops file.pdf

PDF to TXT

$ pdftotext file.pdf

PDF to JPG

$ convert file.pdf image.jpg

Non-exhaustive list of possible conversion

LZWDecode filter

Convert a PDF to Postscript without the LZWDecode filter

$ qpdf --stream-data=uncompress original.pdf decoded.pdf # Decompress it
$ pdftops decoded.pdf decoded.ps # Convert it

Encryption

PDF supports RC4 encryption (40 to 128 bits keys) and AES (128 to 256 with the Extension Level 3). <br /> Beware with empty password.

Password recovering

Brute force a PDF with pdfcrack

$ pdfcrack -w yourDictionnary.txt file.pdf

With john

$ pdf2john.py file.pdf > x.hash
$ john --wordlist=yourDictionnary.txt x.hash

Javascript

2 ways to search for Javascript

$ pdf-parser --search=JavaScript file.pdf 
$ pdfinfo -js file.pdf

Extract an object With jsunpack

$ jsunpack-extractjs file.pdf

With pdf-parser

$ pdf-parser --object 32 --raw file.pdf > file.js

With pdfextract from Origami

$ pdfextract --js file.pdf

De-obfuscate

https://github.com/urule99/jsunpack-n <br />

Online :<br /> http://jsunpack.jeek.org/java/ <br />

Malzilla and SpiderMonkey can also help deobfuscate JavaScript.<br /> Malzilla : <br /> http://www.malzilla.org/downloads.html <br /> SpiderMonkey : <br /> http://www.didierstevens.com/files/software/js-1.7.0-mod.tar.gz <br /> More details coming soon.

Add Javascript to PDF

https://didierstevens.com/files/software/make-pdf_V0_1_6.zip <br /> https://neonprimetime.blogspot.fr/2015/03/how-to-add-javascript-to-pdf.html <br />

Disarming a PDF

$ python pdfid.py --disarm file.pdf

Flash

Search for flash

$ python pdf-parser.py --search flash file.pdf

Extract flash with swf_mastah

$ python swf_mastah.py -f file.pdf -o ./
$ file *.swf

With pdf-parser

$ pdf-parser.py --object 32 --filter --raw file.pdf > flashFile.swf
$ file flashFile.swf

Analysing flash program

$ swfdump -Ddu flashFile.swf > flashFile.txt

More details coming soon.

Sources :information_source:

https://blog.didierstevens.com/category/pdf/ <br /> http://www.decalage.info/file_formats_security/pdf <br /> https://zeltser.com/analyzing-malicious-documents/ <br /> https://code.google.com/archive/p/corkami/wikis/PDFTricks.wiki <br /> https://www.sans.org/reading-room/whitepapers/malicious/owned-malicious-pdf-analysis-33443 <br /> https://digital-forensics.sans.org/blog/2009/12/14/pdf-malware-analysis/ <br /> http://fileformats.archiveteam.org/wiki/PDF <br />