TippingPoint Zero Day Initiative

Apple WebKit attr() Invalid Attribute Memory Corruption Vulnerability

ZDI-09-032: June 8th, 2009


Affected Vendors

Affected Products

TippingPoint™ IPS Customer Protection

TippingPoint IPS customers are protected against this vulnerability by Digital Vaccine protection filter ID 8043. For further product information on the TippingPoint IPS:

Vulnerability Details

This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Apple WebKit. User interaction is required to exploit this vulnerability in that the target must visit a malicious page.

The specific flaw exists in the handling of attr() functions in a CSS content object. When a large numerical value is passed as the argument to the attr() function, a memory corruption will occur which can be leveraged to execute arbitrary coder under the context of the current user.

Vendor Response

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

Disclosure Timeline

    2009-03-26 - Vulnerability reported to vendor
    2009-06-08 - Coordinated public release of advisory


This vulnerability was discovered by:
    Thierry Zoller