US-CERT Technical Cyber Security Alert TA09-088A -- Conficker Worm Targets Microsoft Windows Systems

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National Cyber Alert System

Technical Cyber Security Alert TA09-088A

Conficker Worm Targets Microsoft Windows Systems

Original release date: March 29, 2009
Last revised: March 30, 2009
Source: US-CERT

Systems Affected

* Microsoft Windows

Overview

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.

I. Description

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:

* http://www.symantec.com/norton/theme.jsp?themeid=conficker_worm&inid=us_ghp_link_conficker_worm
* http://www.microsoft.com/protect/computer/viruses/worms/conficker.mspx
* http://www.mcafee.com

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.

II. Impact

A remote, unauthenticated attacker could execute arbitrary code on
a vulnerable system.

III. Solution

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:
http://www.symantec.com/business/security_response/writeup.jsp?docid=2009-011316-0247-99

Microsoft:
http://support.microsoft.com/kb/962007

http://www.microsoft.com/protect/computer/viruses/worms/conficker.mspx

Microsoft PC Safety hotline at 1-866-PCSAFETY, for assistance.

US-CERT encourages users to prevent a Conficker/Downadup infection by
ensuring all systems have the MS08-067 patch (see
http://www.microsoft.com/technet/security/Bulletin/MS08-067.mspx),
disabling AutoRun functionality (see
http://www.us-cert.gov/cas/techalerts/TA09-020A.html), and
maintaining up-to-date anti-virus software.

IV. References

* Microsoft Windows Does Not Disable AutoRun Properly -
<http://www.us-cert.gov/cas/techalerts/TA09-020A.html>

* Virus alert about the Win32/Conficker.B worm -
<http://support.microsoft.com/kb/962007>

* Microsoft Security Bulletin MS08-067 - Critical -
<http://www.microsoft.com/technet/security/Bulletin/MS08-067.mspx>

* MS08-067: Vulnerability in Server service could allow remote code
execution -
<http://support.microsoft.com/kb/958644>

* The Conficker Worm -
<http://www.symantec.com/norton/theme.jsp?themeid=conficker_worm>

* W32/Conficker.worm -
<http://us.mcafee.com/root/campaign.asp?cid=54857>

* W32.Downadup Removal Tool -
<http://www.symantec.com/business/security_response/writeup.jsp?docid=2009-011316-0247-99>

____________________________________________________________________

The most recent version of this document can be found at:

<http://www.us-cert.gov/cas/techalerts/TA09-088A.html>
____________________________________________________________________

Feedback can be directed to US-CERT Technical Staff. Please send
email to <cert@cert.org> with "TA09-088A Feedback VU#827267" in
the subject.
____________________________________________________________________

For instructions on subscribing to or unsubscribing from this
mailing list, visit <http://www.us-cert.gov/cas/signup.html>.
____________________________________________________________________

Produced 2009 by US-CERT, a government organization.

Terms of use:

<http://www.us-cert.gov/legal.html>
____________________________________________________________________

Revision History

March 29, 2009: Initial release
March 30, 2009: Included additional details

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