Vulnerability Note VU#177584

Microsoft Windows kernel vulnerable to a denial-of-service condition via animated cursor (.ani) frame number

Original Release date: 07 Jan 2005 | Last revised: 14 Jan 2005


A vulnerability exists in the way the Microsoft Window's kernel processes animated cursor (.ani) files with a frame number set to zero. Exploitation of this vulnerability may allow a remote attacker to cause a denial-of-service condition.


A vulnerability exists in the way the Microsoft Windows' kernel processes .ani files. These files contain animated graphics for icons and cursors. According to public reports, if the Windows kernel is supplied a .ani file with a frame number set to zero, it doesn't properly handle the .ani file. As a result, the kernel may crash or consume 100% of the system resources resulting in a denial-of-service condition.

.ani files are parsed when the containing folder is opened or it is used as a cursor. In addition, Internet Explorer can process .ani files in HTML documents, so web pages and HTML email messages can also trigger this vulnerability. Other web browsers or programs that render HTML may also act as attack vectors.

Note that it is reported that Windows XP SP2 is not affected by this issue.


If a remote attacker can persuade a user to access a specially crafted ani file, the attacker may be able to crash that user's system.


Apply Patch

Apply a patch as described in Microsoft Security Bulletin MS05-002. Please also note that Microsoft is actively deploying the patches for this vulnerability via Windows Update.

Systems Affected (Learn More)

VendorStatusDate NotifiedDate Updated
Microsoft CorporationUnknown-11 Jan 2005
If you are a vendor and your product is affected, let us know.

CVSS Metrics (Learn More)

Group Score Vector
Base N/A N/A
Temporal N/A N/A
Environmental N/A N/A



This vulnerability was publicly reported by flashsky fangxing.

This document was written by Jeff Gennari.

Other Information

  • CVE IDs: CAN-2004-1305
  • Date Public: 23 Dec 2004
  • Date First Published: 07 Jan 2005
  • Date Last Updated: 14 Jan 2005
  • Severity Metric: 28.35
  • Document Revision: 88


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