CVE-2013-6639 in Chrome
Summary
by MITRE
The DehoistArrayIndex function in hydrogen-dehoist.cc (aka hydrogen.cc) in Google V8 before 3.22.24.7, as used in Google Chrome before 31.0.1650.63, allows remote attackers to cause a denial of service (out-of-bounds write) or possibly have unspecified other impact via JavaScript code that sets the value of an array element with a crafted index.
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Analysis
by VulDB Data Team • 06/02/2021
The vulnerability identified as CVE-2013-6639 represents a critical out-of-bounds write flaw within Google V8's JavaScript engine implementation, specifically within the DehoistArrayIndex function located in hydrogen-dehoist.cc. This issue affects the V8 engine version prior to 3.22.24.7 and impacts Google Chrome versions before 31.0.1650.63, creating a significant security risk for web applications and users. The flaw stems from inadequate bounds checking during array index processing, allowing malicious JavaScript code to manipulate array elements with crafted indices that exceed valid memory boundaries. This vulnerability falls under the Common Weakness Enumeration category CWE-129, which specifically addresses improper validation of array indices, and can be mapped to ATT&CK technique T1059.007 for JavaScript-based exploitation. The root cause lies in the hydrogen compiler's dehoisting optimization process where array index values are not properly validated before being used to access memory locations, creating a pathway for attackers to write data beyond allocated array boundaries.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable more sophisticated attacks including arbitrary code execution or information disclosure. When an attacker crafts JavaScript code that sets array element values with indices that bypass normal bounds checking, the engine's memory management system becomes vulnerable to corruption through out-of-bounds writes. This type of vulnerability is particularly dangerous in browser environments where JavaScript execution is ubiquitous and attacker-controlled input can be seamlessly injected through web pages, web applications, or malicious advertisements. The flaw demonstrates how optimization techniques in modern JavaScript engines can introduce security risks when proper input validation is omitted during the compilation phase, as the hydrogen compiler's attempt to optimize array access patterns inadvertently creates a security boundary that can be exploited. The vulnerability's potential for unspecified other impacts suggests that successful exploitation could lead to complete system compromise, given the privileged execution context of browser JavaScript engines.
Mitigation strategies for CVE-2013-6639 require immediate patching of affected V8 engine versions and Chrome browser installations to prevent exploitation. Organizations should prioritize updating to V8 version 3.22.24.7 or later and Chrome version 31.0.1650.63 or higher, as these releases contain the necessary fixes for proper array index validation. Additionally, implementing content security policies, enabling sandboxing mechanisms, and using automatic updates can significantly reduce the attack surface for this vulnerability. Security teams should also consider deploying web application firewalls that can detect and block suspicious JavaScript patterns associated with array manipulation attacks. The fix typically involves adding proper bounds checking within the DehoistArrayIndex function to validate array indices before memory operations, preventing out-of-bounds write conditions while maintaining the performance benefits of the optimization. This vulnerability underscores the importance of thorough security testing during optimization phases and demonstrates how seemingly benign compiler optimizations can introduce critical security flaws that affect millions of users globally.