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Trojan:BAT/Killav.D


Trojan:BAT/Killav.D is a detection for a batch script which attempts to terminate the Windows Defender process MSASCui.exe.


What to do now

Manual removal is not recommended for this threat. To detect and remove this threat and other malicious software that may have been installed, run a full-system scan with an up-to-date antivirus product such as the Microsoft Safety Scanner (http://go.microsoft.com/fwlink/?LinkId=212742). For more information, see http://www.microsoft.com/protect/computer/viruses/vista.mspx.

Threat behavior

Trojan:BAT/Killav.D is a detection for a batch script which attempts to terminate the Windows Defender process MSASCui.exe.
 
It has been observed being installed by variants of Trojan:Win32/FakeXPA, which also add a registry entry to ensure that the script is run upon system startup.
 
For example, one variant of Trojan:Win32/FakeXPA, going by the name of “Green Antivirus”, installs the file to %AllUsersAppData%\gav\wer.bat and creates the following registry entry:
 
Under key: HKCU\Software\Microsoft\Windows\CurrentVersion\Run
Adds value: <random digits> (eg "67569387646557683")
With data: %AllUsersAppData%\gav\wer.bat
 
Note - %AllUsersAppData% refers to a variable location that is determined by the malware by querying the Operating System. The default installation location for the %AllUsersAppData% directory is '\documents and settings\all users\application data\'.

Analysis by David Wood

Symptoms

System changes
The following system changes may indicate the presence of this malware:
  • Windows Defender may fail to function.

Prevention


Alert level: Severe
First detected by definition: 1.63.1343.0
Latest detected by definition: 1.117.2303.0 and higher
First detected on: Aug 12, 2009
This entry was first published on: Aug 13, 2009
This entry was updated on: Apr 17, 2011

This threat is also detected as:
No known aliases