Hi Andreas Marx, It is ironic that now the AV programs implemented the "smart" file format checking, but "forgot" about file extensions :) I think, that "smart" file format checking must be complemented with the "smart" file extension checking. Regards, Andrey Bayora. ----- Original Message ----- From: "Andreas Marx" <gega-it@xxxxxx> To: "Andrey Bayora" <andrey@xxxxxxxxxxxxxxx>; <bugtraq@xxxxxxxxxxxxxxxxx> Sent: Wednesday, October 26, 2005 12:50 PM Subject: Re: Multiple Vendor Anti-Virus Software Detection Evasion Vulnerability through > > Hi! > > Thanks, that's interesting to read. In 2000, I've found and suggested the following in an article I've written for the Virus Bulletin magazine <http://www.virusbtn.com> : > > "[...] Some scanners do not actually scan all files even when set to "scan all files" or when the mask "*.*" is used. Most of the time at least some infected .BAT, .VBS and .COM files will be missed if they have non-standard extensions. This happens when the scanner checks the file extension, not the content, in order to scan solely for this kind of virus. It would be a good idea for vendors to make a "smart" scan to find out the (hopefully) correct file format. If there is more than one possibility (like ASCII text or a .COM file), all possible supported formats should be scanned. [...]" > > You can find this (Title: "The Usual Suspects ? Part 1", Dec 2000) and more related articles here: > <http://www.av-test.org/sites/references_papers.php3?lang=en> > > cheers, > Andreas Marx > CEO, AV-Test.org > <http://www.av-test.org> > > > > Multiple Vendor Anti-Virus Software Detection Evasion Vulnerability through > > forged magic byte. > > > AUTHOR: Andrey Bayora (www.securityelf.org) > > > For more details, screenshots and examples please read my article "The Magic > > of magic byte" at www.securityelf.org . In addition, you will find a sample > > "triple headed" program which has 3 different 'execution entry points', > > depending on the extension of the file (exe, html or eml) - just change the > > extension and the SAME file will be executed by (at least) THREE DIFFERENT > > programs! (thanks to contributing author Wayne Langlois from > > www.diamondcs.com.au). > > ______________________________________________________________ > Verschicken Sie romantische, coole und witzige Bilder per SMS! > Jetzt bei WEB.DE FreeMail: http://f.web.de/?mc=021193 > > >
