ZDI-06-026: Microsoft Internet Explorer Multiple CSS Imports Memory Corruption Vulnerability http://www.zerodayinitiative.com/advisories/ZDI-06-026.html August 8, 2006 -- CVE ID: CVE-2006-3451 -- Affected Vendor: Microsoft -- Affected Products: Internet Explorer 6 All Versions Internet Explorer 5 SP4 -- TippingPoint(TM) IPS Customer Protection: TippingPoint IPS customers have been protected against this vulnerability since August 8, 2006 by Digital Vaccine protection filter ID 4606. For further product information on the TippingPoint IPS: http://www.tippingpoint.com -- Vulnerability Details: This vulnerability allows attackers to execute arbitrary code on vulnerable installations of Microsoft Internet Explorer. User interaction is required to exploit this vulnerability in that the target must visit a malicious page. The specific flaw exists due to improper garbage collection when multiple "imports" are used on a "styleSheets" collection. Crafting a long chain of CSS imports in an HTML document results in a memory corruption eventually leading to code execution. -- Vendor Response: Microsoft has issued an update to correct this vulnerability. More details can be found at: http://www.microsoft.com/technet/security/bulletin/MS06-042.mspx -- Disclosure Timeline: 2006.06.14 - Vulnerability reported to vendor 2006.08.08 - Digital Vaccine released to TippingPoint customers 2006.08.08 - Coordinated public release of advisory -- Credit: This vulnerability was discovered by Sam Thomas. -- About the Zero Day Initiative (ZDI): Established by TippingPoint, a division of 3Com, The Zero Day Initiative (ZDI) represents a best-of-breed model for rewarding security researchers for responsibly disclosing discovered vulnerabilities. Researchers interested in getting paid for their security research through the ZDI can find more information and sign-up at: http://www.zerodayinitiative.com The ZDI is unique in how the acquired vulnerability information is used. 3Com does not re-sell the vulnerability details or any exploit code. Instead, upon notifying the affected product vendor, 3Com provides its customers with zero day protection through its intrusion prevention technology. Explicit details regarding the specifics of the vulnerability are not exposed to any parties until an official vendor patch is publicly available. Furthermore, with the altruistic aim of helping to secure a broader user base, 3Com provides this vulnerability information confidentially to security vendors (including competitors) who have a vulnerability protection or mitigation product.