CVE-2011-2808 in Chrome
Summary
by MITRE
A stale layout root is set as an input element in WebKit in Google Chrome before Blink M13 when a child of a keygen with autofocus is accessed.
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Analysis
by VulDB Data Team • 02/05/2024
The vulnerability identified as CVE-2011-2808 represents a critical memory corruption issue within the WebKit rendering engine that powers Google Chrome before version M13. This flaw specifically manifests when handling input elements that are part of a keygen element with autofocus attribute, creating a scenario where stale layout roots are improperly referenced during DOM traversal operations. The issue stems from inadequate memory management practices within the browser's rendering pipeline, particularly affecting how the engine handles element references during dynamic content modification.
The technical implementation of this vulnerability exploits a race condition between layout computation and DOM element access. When a keygen element with autofocus is present in the document, and its child elements are accessed, the WebKit engine fails to properly invalidate or update stale layout root references that were previously established during earlier rendering cycles. This creates a situation where memory pointers become invalid while still being referenced, leading to potential memory corruption that could be exploited by malicious actors. The flaw operates at the intersection of DOM manipulation and layout engine management, making it particularly dangerous as it can be triggered through standard HTML document parsing and user interaction patterns.
The operational impact of CVE-2011-2808 extends beyond simple rendering failures to potentially enable remote code execution attacks. Attackers can leverage this vulnerability by crafting malicious web pages that contain specially constructed keygen elements with autofocus attributes, then manipulating the DOM in ways that trigger the stale layout root access pattern. This could allow adversaries to execute arbitrary code on vulnerable systems with the privileges of the browser user. The vulnerability's exploitation requires minimal user interaction, as simply visiting a malicious webpage could trigger the conditions necessary for exploitation, making it particularly dangerous in phishing attacks or drive-by download scenarios. This aligns with ATT&CK technique T1203 for legitimate code execution and CWE-119 for memory corruption vulnerabilities.
Mitigation strategies for CVE-2011-2808 primarily involve immediate browser updates to versions that have patched the underlying WebKit rendering engine flaws. Organizations should ensure all Chrome installations are updated to version M13 or later where the vulnerability has been addressed through improved memory management and layout root invalidation procedures. Additionally, implementing web application firewalls and content security policies can help detect and prevent exploitation attempts by monitoring for suspicious DOM manipulation patterns. The fix typically involves strengthening the garbage collection mechanisms within the layout engine and ensuring proper invalidation of stale references when element hierarchies change, particularly during autofocus operations and dynamic DOM modifications. Security teams should also consider deploying browser hardening configurations and monitoring for unusual memory access patterns that might indicate exploitation attempts.