Virus:TR/Dldr.Agent.awg.4
Date discovered:10/10/2006
Type:Trojan
In the wild:No
Reported Infections:Low
Distribution Potential:Low
Damage Potential:Medium
Static file:Yes
File size:35.328 Bytes
MD5 checksum:cd0B92cc20d1cd6b308077431bc1f8cd
VDF version:6.36.00.87
IVDF version:6.36.00.103 - Friday, October 13, 2006

 General Aliases:
   •  Kaspersky: Trojan-Downloader.Win32.Agent.awg
   •  Sophos: Troj/CarLoad-B
   •  Bitdefender: Trojan.Downloader.Agent.AOV


Platforms / OS:
   • Windows 95
   • Windows 98
   • Windows 98 SE
   • Windows NT
   • Windows ME
   • Windows 2000
   • Windows XP
   • Windows 2003


Side effects:
   • Downloads files
   • Drops a malicious file
   • Registry modification
   • Steals information

 Files The following file is created:

– %SYSDIR%\srvc.dll Further investigation pointed out that this file is malware, too. Detected as: TR/Dldr.Agent.awg.4




It tries to download some files:

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

– The location is the following:
   • %URL from downloaded file%
It is saved on the local hard drive under: %TEMPDIR%\%random character string%.tmp Furthermore this file gets executed after it was fully downloaded.

 Registry The following registry key is added in order to run the process after reboot:

– HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify\
   WLogon
   • "Asynchronous"=dword:00000001
   • "Impersonate"=dword:00000001
   • "StartShell"="Entry"
   • "DllName"="srvc.dll"

 Backdoor Contact server:
The following:
   • http://bebbedaacfefbde.com/b/**********

As a result it may send information and remote control could be provided. This is done via the HTTP POST method using a PHP script.


Sends information about:
    • Computer name

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

    Process name:
   • %WINDIR%\Explorer.EXE

   If successful, the malware process terminates while the injected part remains active.

 Miscellaneous  Checks for an internet connection by contacting the following web site:
   • http://microsoft.com

 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:
   • ASPack

Description inserted by Bogdan Iliuta on Friday, November 10, 2006
Description updated by Bogdan Iliuta on Monday, November 20, 2006

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