Re: Multiple Vendor Anti-Virus Software DetectionEvasion Vulnerability through forged magic byte

[Bipin Gautam <gautam.bipin () gmail com>]

> Consequently, the issue that you describe is *not* a
> vulnerability issue, but rather just an example of a new variant
> that has not yet been added to an AV vendor's database of "known
> viruses".

yap, maybe* but i consider this issue equv. to the 'classic issue' of
adding NOP to the shell-code to bypass IDS/IPS You ain't gonna add
every possible combinations as signatures!


> Instead of beahviour analysis, most AV vendors choose uterly stupid
> PE section fingerprints, defeated by adding a few bytes. Go figure. of
> course this is no vulnerability, it's a feature!

Is, CA eTrust Antivirus, run in Reviewer mode by default?
(sorry, i haven't tryed ant Av lately)

-------------
> My theory on this is simple :
> - ALL files can't be analysed the same way by
> AV engines (due to speed issues) (In other
> words not all analysis/fingerpritns is applied to
> every file)

> The solution was to make the engines a bit "smarter", i.e analyse the
> header to determine the type and then ONLY apply the signatures/heuristics
> which apply to the type of the file (i am not speaking about the extension
> of the file here) thus speeding up the process. Changing the header
> just makes the smart engines look...well...  a bit dumb in my regards.
------


> The AV vendors aren't going to patch their products if they
> don't detect your PoC; they're just going to write a new
> signature or modify an existing signature to detect your
> new variants.  The fact that it can and will be fixed by
> AV signatures instead of product patches should help you
> figure out if this is a product vulnerability issue or just
> a "new virus variant" issue.
-------------

Variant huh?

        My defination of variant are bit straight forward. And sure isn't a
'universal trick' that can be used to modified any malicious
executable (which has known Av signature)  by a 8 year old with 0
programming knowledge or by using any special tools to make it
un-detectable, later. Admit it... Av vendors aren't going to
doyuble/tripple their Av defination to detect all of such possible
varient.
Common, is the execution point of ANY instruction code or program flow
is being changed?

> There are two types of people in the world:  those who
> complain about problems, and those who find solutions to
> problems.  Where's your superior AV scanner?

Lastly, yap I also feel there are 2 type of ppl. in the world. One who
gives answers to a question and the other who askz another another
question AS the answer of the previous question.


-best regards,
Bipin Gautam

Zeroth law of security: The possibility of poking a system from lower
privilege is zero unless & until there is possibility of direct,
indirect or consequential communication between the two...

_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/