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Virus:TR/Drop.Xorer.C
Date discovered:26/02/2008
Type:Trojan
In the wild:Yes
Reported Infections:Low
Distribution Potential:Low to medium
Damage Potential:Medium
Static file:No
File size:~90.000 Bytes
IVDF version:7.00.02.190

 General Method of propagation:
   • Mapped network drives


Aliases:
   •  Mcafee: W32/Xorer.c
   •  Kaspersky: Virus.Win32.Xorer.dr
   •  F-Secure: Virus.Win32.Xorer.dr
   •  Sophos: W32/Xorer-B
   •  Grisoft: Worm/AutoRun.AR
   •  Eset: Win32/Xorer.NAE
   •  Bitdefender: Win32.Xorer.DW


Platforms / OS:
   • Windows 2000
   • Windows XP
   • Windows 2003


Side effects:
   • Disable security applications
   • Downloads files
   • Drops malicious files
   • Lowers security settings
   • Registry modification

 Files It copies itself to the following locations:
   • %SYSDIR%\%several random digits%.log
   • %SYSDIR%\com\lsass.exe
   • %drive%\pagefile.pif



The following files are created:

%drive%\autorun.inf This is a non malicious text file with the following content:
   • %code that runs malware%

%SYSDIR%\com\smss.exe Furthermore it gets executed after it was fully created. Further investigation pointed out that this file is malware, too. Detected as: W32/Xorer.DU

%SYSDIR%\com\netcfg.000 Further investigation pointed out that this file is malware, too. Detected as: TR/Xorer.A.1

%SYSDIR%\com\netcfg.dll Further investigation pointed out that this file is malware, too. Detected as: TR/Xorer.A.1

%SYSDIR%\dnsq.dll Further investigation pointed out that this file is malware, too. Detected as: TR/Agent.32256.E.2

%drive%\NetApi000.sys Further investigation pointed out that this file is malware, too. Detected as: RKIT/Xorer.A.2




It tries to download a file:

– The location is the following:
   • http://w.c0mo.com/**********
This file may contain further download locations and might serve as source for new threats.

 Registry  The following registry keys including all values and subkeys are removed:
   • [HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run]
   • [HKLM\SYSTEM\CurrentControlSet\Control\SafeBoot\Minimal\{4D36E967-E325-11CE-BFC1-08002BE10318}]
   • [HKLM\SYSTEM\CurrentControlSet\Control\SafeBoot\Network\{4D36E967-E325-11CE-BFC1-08002BE10318}]



The following registry keys are changed:

Various Explorer settings:
– [HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced]
   New value:
   • ShowSuperHidden = dword:00000000

– [HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\
   Folder\SuperHidden]
   New value:
   • Type = radio

 Injection –  It injects the following file into a process: %SYSDIR%\dnsq.dll

    Process name:
   • %all running processes%


 Miscellaneous  Checks for an internet connection by contacting the following web site:
   • www.baidu.com


Mutex:
It creates the following Mutex:
   • clsassexe

 File details Programming language:
The malware program was written in MS Visual C++.


Runtime packer:
In order to aggravate detection and reduce size of the file it is packed with the following runtime packer:
   • UPX

Description inserted by Andrei Gherman on Monday, June 16, 2008
Description updated by Andrei Gherman on Thursday, June 19, 2008

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