CVE-2011-3956 in Chrome
Summary
by MITRE
The extension implementation in Google Chrome before 17.0.963.46 does not properly handle sandboxed origins, which might allow remote attackers to bypass the Same Origin Policy via a crafted extension.
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Analysis
by VulDB Data Team • 03/20/2021
The vulnerability identified as CVE-2011-3956 represents a critical sandboxing flaw in Google Chrome's extension architecture that persisted across multiple versions prior to 17.0.963.46. This weakness specifically targets the browser's security model that relies on the Same Origin Policy to isolate web content and extension code from each other. The extension implementation in affected Chrome versions failed to properly enforce sandboxing boundaries when handling origins, creating a potential avenue for privilege escalation and cross-origin data access. The vulnerability stems from improper validation of origin contexts within the extension sandbox, allowing malicious actors to craft specially designed extensions that could circumvent the fundamental security assumptions underlying Chrome's architecture. This flaw directly undermines the browser's security isolation mechanisms that are essential for protecting users from malicious web content and potentially harmful browser extensions.
The technical exploitation of this vulnerability occurs through the manipulation of sandboxed origin handling within Chrome's extension framework, where the browser fails to properly validate or restrict access between different origin contexts. Attackers can leverage this weakness by developing or distributing malicious extensions that exploit the insufficient sandbox boundary enforcement, enabling them to access resources or data that should normally be restricted to specific origins. The flaw essentially creates a pathway where extensions running in one origin context can potentially interact with or access data from another origin, bypassing the core security principle that prevents unauthorized cross-origin operations. This vulnerability operates at the intersection of browser security architecture and extension management, where the expected isolation between different extension contexts becomes compromised. The exploitation mechanism relies on understanding how Chrome's extension sandboxing model interacts with origin-based access controls, specifically targeting the point where these security models should intersect but fail to do so properly.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass significant data exposure and potential system compromise. Remote attackers who successfully exploit this weakness can effectively bypass the Same Origin Policy, which serves as one of the fundamental pillars of web security. This allows for unauthorized data access, potential information disclosure, and could enable more sophisticated attacks such as cross-site scripting or data exfiltration. The vulnerability affects all users of affected Chrome versions, making it particularly dangerous as it can be exploited through malicious extensions distributed via legitimate extension stores or direct downloads. Security researchers have noted that this flaw aligns with common attack patterns described in the attack tactics and techniques framework, particularly those related to privilege escalation and sandbox bypass. The vulnerability also corresponds to specific CWE classifications related to improper handling of security boundaries and sandboxing failures, highlighting the architectural nature of the weakness rather than a simple coding error.
Mitigation strategies for CVE-2011-3956 primarily focus on immediate software updates to versions that properly address the sandboxing implementation. Users should upgrade to Chrome version 17.0.963.46 or later, where Google implemented fixes to properly handle sandboxed origins within extension contexts. System administrators should enforce automatic updates where possible and conduct regular security audits of installed extensions to identify potentially malicious code. The security community has recommended that users avoid installing extensions from untrusted sources and maintain awareness of extension permissions requested by installed browser extensions. Organizations should consider implementing browser security policies that restrict extension installation and usage, particularly in enterprise environments where the attack surface needs careful management. Additional defensive measures include monitoring for suspicious extension behavior and implementing network-level controls that can detect and block unauthorized cross-origin access attempts. The fix implemented by Google addresses the core issue by strengthening the validation of origin contexts within the extension sandbox, ensuring that proper boundary enforcement occurs between different origin environments. This vulnerability serves as a reminder of the critical importance of proper sandbox implementation in modern browsers and the potential consequences of inadequate security boundary enforcement.