Published May 04, 2006 | Updated Sep 15, 2017


High |Detected with Windows Defender Antivirus

Aliases: No associated aliases


Windows Defender Antivirus detects and removes this threat.
Win32/Cissi is a mass-mailing and network worm with a backdoor component. The worm can spread to remote NetBIOS shares by trying weak account name and password combinations. Some variants of the worm can gather email addresses from the infected computer and send a copy of the worm to those addresses as an e-mail attachment. Win32/Cissi has an additional component that connects to an IRC server to serve as a backdoor.

Use the following free Microsoft software to detect and remove this threat:

You should also run a full scan. A full scan might find hidden malware.

Get more help

You can also visit our advanced troubleshooting page or search the Microsoft virus and malware community for more help.

If you’re using Windows XP, see our Windows XP end of support page.

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