Microsoft Windows is prone to a stack buffer-overflow vulnerability because of insufficient format validation that occurs when handling malformed ANI cursor or icon files. An attacker can exploit this issue to execute arbitrary code with the privileges of an unsuspecting user. A successful attack can result in the compromise of affected user accounts and computers. This issue affects Windows Vista, Windows XP SP2, and Windows Server 2003 SP1 when running Internet Explorer 6 and 7; other versions and client applications may also be affected. Microsoft has recently disclosed that Outlook 2007 is not vulnerable, that Windows Mail on Vista is vulnerable in replying to or forwarding emails containing malicious ANI files, and that Outlook Express is vulnerable to this issue. Third-party applications such as browsers that handle ANI files and call the ANI rendering functionality in GDI pose an attack vector for this vulnerability.
Run all software as a nonprivileged user with minimal access rights.
To reduce the impact of latent vulnerabilities, always run non-administrative software as an unprivileged user with minimal access rights.
Deploy network intrusion detection systems to monitor network traffic for malicious activity.
Deploy NIDS to monitor network traffic for signs of anomalous or suspicious activity including unexplained incoming and outgoing traffic. This may indicate exploit attempts or activity that results from successful exploits
Do not accept or execute files from untrusted or unknown sources.
Users should not accept or execute files provided by an untrusted or unknown source.
Do not follow links provided by unknown or untrusted sources.
Since a likely vector of attack for this issue is the distribution of malicious HTML documents, users should not follow links provided by unknown or untrusted individuals.
Microsoft has released an advisory to address this issue in supported versions of affected applications. Please see the referenced advisory for details on obtaining and applying the appropriate updates.