ZDI-11-104: (Pwn2Own) Webkit CSS Text Element Count Remote Code Execution Vulnerability

2011-04-19T00:00:00
ID SECURITYVULNS:DOC:26167
Type securityvulns
Reporter Securityvulns
Modified 2011-04-19T00:00:00

Description

ZDI-11-104: (Pwn2Own) Webkit CSS Text Element Count Remote Code Execution Vulnerability

http://www.zerodayinitiative.com/advisories/ZDI-11-104

April 14, 2011

-- CVE ID: CVE-2011-1290

-- 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 11087. 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 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 the WebKit library's implementation of a CSS style. When totaling the length of it's string elements, the library will store the result into a 32bit integer. This value will be used for an allocation and then later will be used to initialize the allocated buffer. Due to the number of elements being totaled being variable, this will allow an aggressor to provide as many elements as necessary in order to cause the integer value to wrap causing an under-allocation. Initialization of this data will then cause a heap-based buffer overflow. This can lead to code execution under the context of the application.

-- Vendor Response: Apple patch on April 14, 2011: http://support.apple.com/kb/HT4606 http://support.apple.com/kb/HT4607 http://support.apple.com/kb/HT4596

-- Disclosure Timeline: 2011-03-31 - Vulnerability reported to vendor 2011-04-14 - Coordinated public release of advisory

-- Credit: This vulnerability was discovered by: * Anonymous * Vincenzo Iozzo, Willem Pinckaers, and Ralf-Philipp Weinmann

-- About the Zero Day Initiative (ZDI): Established by TippingPoint, The Zero Day Initiative (ZDI) represents a best-of-breed model for rewarding security researchers for responsibly disclosing discovered vulnerabilities.

Researchers interested in getting paid for their security research through the ZDI can find more information and sign-up at:

http://www.zerodayinitiative.com

The ZDI is unique in how the acquired vulnerability information is used. TippingPoint does not re-sell the vulnerability details or any exploit code. Instead, upon notifying the affected product vendor, TippingPoint provides its customers with zero day protection through its intrusion prevention technology. Explicit details regarding the specifics of the vulnerability are not exposed to any parties until an official vendor patch is publicly available. Furthermore, with the altruistic aim of helping to secure a broader user base, TippingPoint provides this vulnerability information confidentially to security vendors (including competitors) who have a vulnerability protection or mitigation product.

Our vulnerability disclosure policy is available online at:

http://www.zerodayinitiative.com/advisories/disclosure_policy/

Follow the ZDI on Twitter:

http://twitter.com/thezdi