Gop belongs to a family of passwords stealing trojans. This trojan seems to be written in China. The trojan is designed to steal OICQ (Chinese clone of ICQ?) passwords.
Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.
When run the trojan installs itself to the system. While installing the trojan copies itself to Windows, Windows system or TEMP directory and registers itself in system registry auto-run section. For example:
Trojan's full name:
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run WindowsAgent = winzipauto.exe
The installed trojan file name, the target directory are optional. They are stored in encrypted form in trojan file at the file end. To steal OICQ data the trojan also drops additional DLL file (hooker) with optional name. A hacker may configure optional data before sending trojan to a victim machine, or before put it on a web site.
There other optional features of this trojan:
display decoy (fake) messsage, and the message text delete original file after installing into the system email address to there stolen data is being sent (default - email@example.com) smtp server to there the data is being sent (default - smtp.sina.com.cn)
The trojan then registers itself in the system as hidden aplication (service), the trojan process then is not visible in task list. Being active in the system trojan periodically sends email messages to its host (hacker's email address).
There are known "upgrated" version of this trojan that do mail themselves, and are "Internet worms" as a result. See the description of Gop worm.
Technical Details: Kaspersky Labs; January 2002