Summary

Ouch.A is a Java applet based trojan that downloads and installs WinShow (winshow.dll) spyware on the system.

Ouch activates when user views a web page or HTML email that contains reference to the trojan file.

Ouch does not replicate and does not infect the host system, the only operations it does is to download and install WinShow spyware component.

Additional Details

When a JAR file containing the trojan is executed it uses Microsoft Internet Explorer VerifierBug vulnerability to get full privileges by escaping the Java security, and execute its code. Then the trojan downloads the winshow.dll into windows directory (default C:\Windows) and registers it with regsvr32.

To remove Ouch.A from your system apply the fix to the Java VM vulnerability and clear temporary Internet files cache

Further information about the vulnerability in the Microsoft Java VM, including a fix, is available at: http://www.microsoft.com/technet/security/bulletin/ms03-011.asp







Write-up: Jarno Niemela, September 2nd, 2003;

Description Updated: Jarno Niemela, January 12th, 2004;