ZDI-11-140: Webkit Detached Body Element Remote Code Execution Vulnerability

ZDI-11-140 (formerly ZDI-CAN-1026): Webkit Detached Body Element Remote Code
Execution Vulnerability

http://www.zerodayinitiative.com/advisories/ZDI-11-140

April 19, 2011

– CVSS:
9, (AV:N/AC:L/Au:N/C:P/I:P/A:C)

– Affected Vendors:
WebKit

– Affected Products:
WebKit WebKit

– TippingPoint(TM) IPS Customer Protection:
TippingPoint IPS customers have been protected against this
vulnerability by Digital Vaccine protection filter ID 11102.
For further product information on the TippingPoint IPS, visit:

http://www.tippingpoint.com

– Vulnerability Details:
This vulnerability allows remote attackers to execute arbitrary code on
vulnerable installations of Apple Safari 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 within how the application manages a reference
to an anonymous block located near a particular element within the
document. When cloning this element, the application will duplicate a
reference to the block and then later re-attach this element to the
rendering tree. During this process the library will free the original
rendering element. Subsequent access to the same element will then cause
the library to use the freed object. This can be utilized to achieve
code execution under the context of the application.

– Vendor Response:
Webkit fix:
http://trac.webkit.org/changeset/67182

– Disclosure Timeline:
2011-03-31 - Vulnerability reported to vendor
2011-04-19 - Public release of advisory

– Credit:
This vulnerability was discovered by:
* Rob King [email protected]

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