TippingPoint Zero Day Initiative

Microsoft Internet Explorer Malformed CSS Memory Corruption Vulnerability

ZDI-09-012: February 10th, 2009


Affected Vendors

Affected Products

TippingPoint™ IPS Customer Protection

TippingPoint IPS customers are protected against this vulnerability by Digital Vaccine protection filter ID 6761. For further product information on the TippingPoint IPS:

Vulnerability Details

This vulnerability allows remote 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 when processing, in XHTML strict mode, a CSS stylesheet containing a specific combination of style directives one of which must be a 'zoom'. The fault in processing results in a memory corruption vulnerability which can be leveraged to execute arbitrary code under the context of the current user.

Vendor Response

Microsoft has issued an update to correct this vulnerability. More details can be found at:

Disclosure Timeline

    2008-10-15 - Vulnerability reported to vendor
    2009-02-10 - Coordinated public release of advisory


This vulnerability was discovered by:
    Sam Thomas of eshu.co.uk