New Threat to Computers Discovered April 9

Researchers discovered a new variant of the Conficker Worm on April 9, 2009. This variant updates earlier infections via its peer to peer (P2P) network as well as resuming scan-and-infect activity against unpatched systems. Public reporting indicates that this variant attempts to download additional malicious code onto victim systems, possibly including copies of the Waledac Trojan, a spam-oriented malicious application which has previously propagated only via bogus email messages containing malicious links. 

U.S. Computer Emergency Readiness Team (US-CERT) is aware of public reports indicating a widespread infection of the Conficker/Downadup worm, which can infect a Microsoft Windows system from a thumb drive, a network share, or directly across a corporate network, if the network servers are not patched with the MS08-067 patch from Microsoft.

Home users can apply a simple test for the presence of a Conficker/Downadup infection on their home computers. The presence of a Conficker/Downadup infection may be detected if a user is unable to surf to their security solution website or if they are unable to connect to the websites, by downloading detection/removal tools available free from those sites:

• Norton from Symantec
• Microsoft
• McAfee

If a user is unable to reach any of these websites, it may indicate a Conficker/Downadup infection. The most recent variant of Conficker/Downadup interferes with queries for these sites, preventing a user from visiting them. If a Conficker/Downadup infection is suspected, the system or computer should be removed from the network or unplugged from the Internet - in the case for home users.

Instructions, support and more information on how to manually remove a Conficker/Downadup infection from a system have been published by major security vendors. Please see below for a few of those sites.
Each of these vendors offers free tools that can verify the presence of a Conficker/Downadup infection and remove the worm:

• Symantec
• Microsoft - Help and Support
• Microsoft - Protect yourself from the Conficker computer worm

You may also call the Microsoft PC Safety hotline at 1-866-PCSAFETY, for assistance.

UPDATED: US-CERT encourages users to take the following preventative measures to help prevent a Conficker/Downadup infection:

• Ensure all systems have the MS08-067 patch.
• Disable AutoRun functionality. See US-CERT Technical Cyber Security Alert TA09-020A.
• Maintain up-to-date antivirus software.
• Do not follow unsolicited links and do not open unsolicited email messages.
• Use caution when visiting untrusted websites.
• Use caution when downloading and installing applications.
• Obtain software applications and updates directly from the vendor's website.
• Refer to the Recognizing and Avoiding Email Scams (pdf) document for more information on avoiding email scams.
• Refer to the Avoiding Social Engineering and Phishing Attacks document for more information on social engineering attacks.

Source: US-CERT