Technical Cyber Security Alert TA09-088A.

National Cyber Alert System
Technical Cyber Security Alert TA09-088A

Conficker Worm Targets Microsoft Windows Systems

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

Systems Affected

* Microsoft Windows


US-CERT is aware of public reports indicating a widespread
infection of the Conficker worm, which can infect a Microsoft
Windows system from a thumb drive, a network share, or directly
across a network if the host is not patched with MS08-067.

I. Description

The presence of a Conficker infection may be detected if a user is
unable to surf to the following websites:


If a user is unable to reach either of these websites, a Conficker
infection may be indicated (the most current variant of Conficker
interferes with queries for these sites, preventing a user from
visiting them). If a Conficker infection is suspected, the
infected system should be removed from the network. Major
anti-virus vendors and Microsoft have released several free tools
that can verify the presence of a Conficker infection and remove
the worm. Instructions for manually removing a Conficker infection
from a system have been published by Microsoft in

II. Impact

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

III. Solution

US-CERT encourages users to prevent a Conficker infection by
ensuring all systems have the MS08-067 patch (part of Security
Update KB958644, which was published by Miscrosoft in October
2008), disabling AutoRun functionality (see, and
maintaining up-to-date anti-virus software.

IV. References

* Virus alert about the Win32/Conficker.B worm –
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* Microsoft Security Bulletin MS08-067 – Critical –
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* Microsoft Windows Does Not Disable AutoRun Properly –
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* MS08-067: Vulnerability in Server service could allow remote code
execution –
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* The Conficker Worm –
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* W32/Conficker.worm –
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The most recent version of this document can be found at:

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