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.
Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.
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:
Description Created: Jarno Niemela, September 2nd, 2003
Description Last Modified: Jarno Niemela, January 12th, 2004