April 11, 2006
Microsoft Internet Explorer is prone to a memory-corruption vulnerability. This is related to the handling of certain HTML tags. Attackers could exploit this issue via a malicious web page to execute arbitrary code in the context of the currently logged-in user. They could also use HTML email for the attack.
- Microsoft Internet Explorer 6.0
- Microsoft Internet Explorer 6.0 SP1
Run all software as a nonprivileged user with minimal access rights.
Ensure that all non-administrative tasks, such as browsing the web and reading email, are performed as an unprivileged user with minimal access rights.
Do not follow links provided by unknown or untrusted sources.
Users should never visit websites of questionable integrity or follow links provided by unfamiliar or untrusted sources.
Set web browser security to disable the execution of script code or active content.
Disabling scripting and active content in the Internet Zone may limit exposure to this and other vulnerabilities.
Implement multiple redundant layers of security.
As an added precaution, deploy memory-protection schemes (such as non-executable stack/heap configuration and randomly mapped memory segments). This may complicate exploitation of memory-corruption vulnerabilities.
Disable any services that are not needed.
Disable support for HTML email in the email client. This may limit email-based attack vectors for this and other vulnerabilities.
Microsoft has released a cumulative security update to address this issue. Updates for Internet Explorer on Windows 98/98SE/ME may be obtained through Windows Update. Reportedly, the fixes provided in MS06-013 may cause unintended breakage with certain ActiveX controls. Symantec has not confirmed this. Before deploying this patch in production environments, test the patch thoroughly to ensure that it doesn't interfere with other software.
Thomas Waldegger is credited with the discovery of this vulnerability.
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