TippingPoint Zero Day Initiative
 

Mozilla Firefox CSS Letter-Spacing Heap Overflow Vulnerability

ZDI-06-010: April 17th, 2006

CVE ID

Affected Vendors

Affected Products

TippingPoint™ IPS Customer Protection

TippingPoint IPS customers are protected against this vulnerability by Digital Vaccine protection filter ID 4097. For further product information on the TippingPoint IPS:

Vulnerability Details

This vulnerability allows attackers to execute arbitrary code on vulnerable installations of the Mozilla/Firefox web browser and Thunderbird e-mail client. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious e-mail.

The specific flaw is due to incorrect handling of the CSS "letter-spacing" element. By specifying a large number, an attacker can overflow an integer used during memory allocation. The under-allocated buffer is later used to store user-supplied data leading to an exploitable heap overflow.

Vendor Response

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

Disclosure Timeline

    2006-01-31 - Vulnerability reported to vendor
    2006-04-17 - Coordinated public release of advisory

Credit

This vulnerability was discovered by:
    Anonymous