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Re: All Antivirus, Trojan, Spy ware scanner, Nested file manual scan bypass bugs. [Part IV]
From: bipin gautam <visitbipin () yahoo com>
Date: Sat, 2 Oct 2004 06:02:24 -0700 (PDT)


--- 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 scanner
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 mentioned
the fact, its MORE* a NTFS file permission problem.

http://www.geocities.com/visitbipin/all.html

IF A FILE PERMISSION IS SET IN A WAY... only THE OWNER
OF THE FILE HAS ACCESS TO THAT FILE, Even softwares
running with ADMINISTRATIVE or SYSTEM privilage don't
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 as
a admin. or system process. Regarding your statement, 

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 a
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 administrator
if administrator is
recovery agent.


wow, i didn't thought of this.....

bipin


                
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