Just An Application

August 26, 2014

Anatomy Of A PDF: Afterword

Filed under: CVE, CVE-2013-2729, PDF, PDF Vulnerability, Security — Tags: , , , — Simon Lewis @ 7:14 am

Since I started writing these posts anonymous benefactors have very kindly presented me with two further versions of the original PDF to add to my collection.

I say versions because although they both possess exactly the same structure as the original, the size of Object 1 is slightly different in each one and the binary sludge is different.

This of course means that the hash of the file will be different in each case, which in turn means it is very likely that any hash based AV scanner will miss these slightly different versions unless they are kept updated with the hashes of these new versions as they appear.

Looking at the actual XML it is apparent that the obfuscation of the Javascript has resulted in different variable names in each version but that there is no difference between what is obfuscated and what is not in any of them.

One additional thing all three versions have in common is that I suspect they won’t actually work.

There is no question what they are trying to do and how they are trying to do it, and at least one version has been seen in the wild by someone else that works, but it is a distinct possibility that the versions I have do not.

I have no way of proving this one way or another as I do not have access to the appropriate environment.

If I am wrong and they will in fact do what they are intended to do I would obviously be interested in knowing why I am wrong. It is all grist to the mill.

If I am right then it is all to the good, at least these particular versions cannot cause any damage, so for obvious reasons I am not going to say why they will not work as intended other than that it is a very simple mistake.

Copyright (c) 2014 By Simon Lewis. All Rights Reserved.

Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and owner Simon Lewis is strictly prohibited.

Excerpts and links may be used, provided that full and clear credit is given to Simon Lewis and justanapplication.wordpress.com with appropriate and specific direction to the original content.


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