CVE-2015-6769 in Chrome
Summary
by MITRE
The provisional-load commit implementation in WebKit/Source/bindings/core/v8/WindowProxy.cpp in Google Chrome before 47.0.2526.73 allows remote attackers to bypass the Same Origin Policy by leveraging a delay in window proxy clearing.
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Analysis
by VulDB Data Team • 06/28/2022
The vulnerability identified as CVE-2015-6769 resides within the WebKit rendering engine's implementation of provisional load commit handling, specifically in the WindowProxy.cpp file that manages cross-origin security boundaries. This flaw represents a critical bypass of the fundamental Same Origin Policy that forms the cornerstone of web security architecture, allowing malicious actors to circumvent browser security controls through carefully crafted timing attacks. The vulnerability manifests during the provisional load phase when a browser is in the process of transitioning between different origins, creating a temporary window where security checks may be prematurely bypassed.
The technical implementation flaw stems from a race condition in the window proxy clearing mechanism that occurs during navigation transitions. When a browser initiates a provisional load, it creates a temporary proxy object that represents the target window context. The vulnerability exploits the timing gap between when this proxy is created and when it is properly cleared, allowing attackers to inject malicious code or access restricted resources during this interim period. This timing-based attack vector specifically targets the window proxy management code path that handles cross-origin navigation scenarios, where the security boundary checking logic fails to properly validate the state of the proxy object during its transitional phase.
The operational impact of this vulnerability extends beyond simple privilege escalation as it fundamentally undermines the browser's security model that protects users from malicious websites attempting to access data from other origins. Attackers can leverage this vulnerability to perform cross-site scripting attacks, access sensitive information from other domains, or potentially execute arbitrary code within the browser context. The vulnerability affects all versions of Google Chrome prior to 47.0.2526.73 and represents a significant risk to web users who may encounter malicious websites during navigation transitions. This flaw particularly impacts enterprise environments where users may be browsing untrusted content and could lead to data exfiltration, session hijacking, or further exploitation through chained attacks.
The vulnerability aligns with CWE-345: Insufficient Verification of Data Authenticity, as it demonstrates how timing-based attacks can bypass security controls that should maintain strict verification of object states during cross-origin transitions. From an ATT&CK framework perspective, this vulnerability maps to T1059.007: Command and Scripting Interpreter: JavaScript and T1566: Phishing, as attackers can exploit this weakness to execute malicious JavaScript code or deliver phishing content that leverages the bypassed security controls. The attack requires minimal user interaction beyond visiting a malicious website, making it particularly dangerous in phishing campaigns or drive-by download scenarios where the timing of the attack can be precisely controlled to exploit the window proxy clearing delay. Mitigation efforts should include immediate browser updates to version 47.0.2526.73 or later, along with network-level security controls that monitor for suspicious navigation patterns and implement additional security headers to protect against cross-origin attacks.