TippingPoint Zero Day Initiative

Apple WebKit RTL LineBox Overflow Remote Code Execution Vulnerability

ZDI-10-152: August 11th, 2010


CVSS Score

Affected Vendors

Affected Products

Vulnerability Details

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

The specific flaw exists due to the method by which the Webkit library renders right-to-left text. If a linebox has a width greater than it's container, Webkit frees an object that upon page destruction is freed again. An attacker can exploit this to code execute remote code under the context of the application.

Vendor Response

Apple states:

this issue was fixed in Safari 4.0.5, and iOS 4 for iPhone and iPod touch iOS 3.2
iOS 4: http://support.apple.com/kb/HT4225
Safari 4.0.5: http://support.apple.com/kb/HT4070

Disclosure Timeline

    2010-02-18 - Vulnerability reported to vendor
    2010-08-11 - Coordinated public release of advisory


This vulnerability was discovered by:
    wushi of team509