ZDI-10-098: Apple Webkit First-Letter Pseudo-Element Style Remote Code Execution Vulnerability http://www.zerodayinitiative.com/advisories/ZDI-10-098 June 8, 2010 -- CVE ID: CVE-2010-1401 -- Affected Vendors: Apple -- Affected Products: Apple WebKit -- TippingPoint(TM) IPS Customer Protection: TippingPoint IPS customers have been protected against this vulnerability by Digital Vaccine protection filter ID 9871. 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's Webkit. User interaction is required in that a user must visit a website or open a malicious document. The specific flaw exists within the way Webkit implements the 'first-letter' css style. If a container with the first-color style has it's contents replaced with a particular element, the library will create a dual reference of the style in order to apply to its contents. Later when the element is freed, the dangling reference will still be applied to the style. Upon navigating the document's styles for either repainting or style recalculation, the application will access the freed memory which can lead to code execution under the context of the application. -- Vendor Response: Apple has issued an update to correct this vulnerability. More details can be found at: http://support.apple.com/kb/HT4196 -- Disclosure Timeline: 2010-02-23 - Vulnerability reported to vendor 2010-06-08 - Coordinated public release of advisory -- Credit: This vulnerability was discovered by: * wushi of team509 -- 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
