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Minor Updates – PESectionExtractor and PECluester

November 12, 2013 in PECluester, PESectionExtractor, Software Releases

Just quick note that I have updated:

  • PESectionExtractor. It’s just a minor fix to make it parse PE32+ files.
  • PECluester. Again, it’s just a minor fix for parsing the arguments + dates.

PESectionExtractor – Extracting PE sections and their strings

September 2, 2012 in Malware Analysis, PESectionExtractor, Software Releases

In my old post I mentioned that one way to extract sections from Portable Executabls is to use 7zip. This, of course is not an elegant solution, so I wrote a script to do it in a more generic way.

The script attached to this post allows to:

  • extract PE sections to separate files

  • extract strings from all sections providing a context for each string

  • extract strings from all sections providing a context for each string, but in a bit smarter way i.e. excluding strings from sections named .rsrc/.reloc as they often contain a lot of strings that are just random data (e.g. from bitmaps or bytes by chance appearing to look like a ‘meaningful’ sequence of characters)

Notably, the string extraction excludes the appended data – this is a good news if you run the script over e.g. installers.  Installers, as explained in my older post, are very often setup.exe (stub) files with appended data that is compressed/encrypted and doesn’t provide any value to analysts unless decompressed/decrypted.

If the script fails to work, it is most likely a result of a packer/protector that makes some of the PE structures corrupted on purpose (e.g. using values outside reasonable boundaries that are still accepted by the Windows PE loader). The practical value of analysing sections/strings extracted from protected/packed/corrupted files is usually low, so I don’t add any checks in the scripts to detect such cases. Many of these techniques are discussed by Ange and he also offers practical examples – files that he crafted manually to test certain properties of PE files, so if you want to know more about this subject and perhaps improve the script his web site will give you all the info you need.

Btw. if you like python, you can easily toy around with Ero Carrera’s pefile module and re-create the script with the same/better functionality.

You can download PESectionExtractor.pl script here.