Trojan and Adware - Vundo (VirtuMonde/VirtuMundo)

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(Continued from previous part...)

Detecting Trojan Vundo with McAfee VirusScan

I decided to take a look at those suspicious DLL files on my own computer. The results are very interesting. I want to share with you here.

1. The first interesting note is on how McAfee VirusScan reacts to the DLL files. As I unzip the bho_200610.zip file that contains those suspicious DLL files, McAfee VirusScan On-Access Scan pops up a window telling that:

fcissfvg.dll   Vundo   Trojan  Deleted
lyssmlnb.dll   Vundo   Trojan  Deleted

Okay. This is nice. VirusScan is doing the job to pretect my system. But it only detected 2 out 3 DLL files. What happens to the third DLL file, yjsallam.dll? Did VirusScan fail to do the job or yjsallam.dll is not a Vundo infected file?

I believe VirusScan failed to do the detection job. But I can not prove it.

2. The second interesting note is on the impact left on my Windows system after McAfee VirusScan detected Trojan Vundo. When tried to shut down my Windows system after unzipping bho_200610.zip and closing McAfee VirusScan detection report window, my system, Windows XP, did close all applications normally. But it failed to shutdown completely with only the desktop background image on the screen. Nothing else is running.

I tried to push the power off button, but the system refused to shutdown. I have to remove the external power supply and remove the battery. That, of course, turned off the system completely.

Then I put the power supply back, and turned on the system. Windows started without any trouble. VirusScan did not report any issues. So may be it's normal for VirusScan to hold your shut down process to prevent triggering Vundo program again.

I did repeat 3 times of playing with McAfee VirusScan on those suspicious DLL files. I got exactly the same results:

• VirusScan failed to report Vundo on yjsallam.dll.
• VirusScan caused my system not able to shutdown after scanning Vundo DLL files.

Full Removal of Trojan Vundo

If you search the Web for intructions for a full removal of Trojan Vundo, you will get many answers. Here is a partial list of what I got out of the Web:

1. From http://vil.nai.com/vil/content/v_127690.htm. This is the official McAfee site. It suggests you to:

• Download Process Explorer (procexp.exe) from http://www.sysinternals.com/ntw2k/freeware/procexp.shtml.
• Reboot the infected machine
• Launch the VirusScan On-Demand Scanner (ODS), or the command-line scanner, but don't initiate the scan yet
• Run Process Explorer and suspend the Explorer.exe, Winlogon.exe, and rundll32.exe processes (right-click on these process names and choose suspend)
• Scan and clean with the current DAT files and engine (the Window launched in step 3 above) [there will be clean failures, that is expected]
• Physically power the machine off and back on.(a hard reset is required as Windows will not shutdown without Winlogon.exe running, and resuming that process will revert the changes made by the scanner).

This sounds like a very manual and risky process. Not suitable for regular home computer users. Even myself, I don't want to try this with my system.

2. From http://www.symantec.com/security_response/writeup.jsp?docid=2004-112210-3747-99. This is the official Symantec site. It suggests you to:

• Download the FixVundo.exe file from: http://securityresponse.symantec.com/avcenter/FixVundo.exe.
• Turn off System Restore if you using Windows Me or XP.
• Double-click the FixVundo.exe file to start the removal tool.
• Click Start to begin the process, and then allow the tool to run.
• Restart the computer.

(Continued on next part...)

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