Re: [Full-Disclosure] (confirm) Antivirus, Trojan, Spy ware scanner, Nested file manual scan bypass bugs. [Part IV]
From: bipin gautam (visitbipin_at_yahoo.com)
To: email@example.com Date: Sat, 2 Oct 2004 07:03:35 -0700 (PDT)
Only tested on...
Mcafee VirusScan professional (188.8.131.52)
Norton Antivirus 2003
This is what i did,
I craeated a account named "dumb_user" and log on to
I created a folder and copied a sample virus to the
folder. Then i took the ownership
of the folder and set the permission as, "I only can
access" the folder and its
eg: cacls.exe hUNT.exe /T /C /P dumb_user:R
Then I switched back to "Administrative account" and
tried doing "manual scan"
for virus with mcafee and later norton in seperate
machines. The manual scan was unable
to pick the virus!!!
But ya... if you try the same thing with a file and
try executing the file the
auto-protect engine will stop the virus from
executing. So this is ONLY ISSUE FOR MANUAL
SCAN ON ANTIVIRUS PRODUCTS.
It seems like, in manual scan... the scanner runs
under the security content of
Administrator who is responsible for scanning the
system........... hence the virus goes
unnoticed due to NTFS file permission restriction.
But, seems like... the Auto-Protect
engine loads as a kernel driver so the virus gets
stopped in the way during execution.
*But ya... many trojan, spyware scanner i know just
run with the Administrative privilage,
so its a ISSUE for all those products.
Please follow the procidure & confirm if other
antivirus products are vulnerable as well.
thank you for your time,
--- bipin gautam <firstname.lastname@example.org> wrote:
> --- 3APA3A <3APA3A@SECURITY.NNOV.RU> wrote:
> > Dear bipin gautam,
> > Your statements about "all antivirus" and "design
> > fault" are wrong, it's
> > strongly depend on the way manual scanning is
> > implemented in specific
> > product.
> > 1. many antiviral products implement their own
> > kernel driver to access
> > scanned file. For this case permissions have no
> > impact for scanning.
> hello 3APA3A,
> Ok ya... i already mentioned the fact, If the
> is unable to drop the privilege and run under the
> security content of "dumb_user" the malicious code
> goes undetected. Correct me if i am wrong, but....
> mostly (full-)system "manual scan" is executed as a
> administrative job......... and i've already
> the fact, its MORE* a NTFS file permission problem.
> IF A FILE PERMISSION IS SET IN A WAY... only THE
> OF THE FILE HAS ACCESS TO THAT FILE, Even softwares
> running with ADMINISTRATIVE or SYSTEM privilage
> have access to the file, normally!!!!!!!!! Really
> strange, cauz root should have atlest read access to
> any file in the system regardless of the permission.
> Atlest, most trojan, spyware scanner gets executed
> a admin. or system process. Regarding your
> >antiviral products implement their own
> > kernel driver to access
> > scanned file.
> I tested on norton av 2003 and few spyware product
> "the cleaner" "Ad-aware" and by this way....... a
> trojan bypassed the protection.
> Guys, please confirm this issue then.... i ain't in
> research lab, just using my home PC. i'll test the
> issue with mcafee and be back with the results
> > You still can bypass antiviral protection for
> > manual scans with file
> > encryption (on-access scanners may impersonate
> > accessing user). This
> > time file can only be scanned by
> > if administrator is
> > recovery agent.
> wow, i didn't thought of this.....
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