CVE-2013-6646 in Chrome
Summary
by MITRE
Use-after-free vulnerability in the Web Workers implementation in Google Chrome before 32.0.1700.76 on Windows and before 32.0.1700.77 on Mac OS X and Linux allows remote attackers to cause a denial of service or possibly have unspecified other impact via vectors related to the shutting down of a worker process.
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Analysis
by VulDB Data Team • 06/08/2021
The vulnerability identified as CVE-2013-6646 represents a critical use-after-free flaw within Google Chrome's Web Workers implementation across multiple operating systems. This security defect exists in versions prior to 32.0.1700.76 for Windows and before 32.0.1700.77 for Mac OS X and Linux platforms, creating a significant risk for users of affected browser versions. The vulnerability specifically targets the process of shutting down worker processes, which are essential components that enable background execution of JavaScript code without blocking the user interface. This flaw falls under the Common Weakness Enumeration category CWE-416, which specifically addresses use-after-free conditions where memory is accessed after it has been freed, potentially leading to unpredictable behavior and security exploits.
The technical execution of this vulnerability involves malicious web content that manipulates the Web Workers API in a manner that triggers improper memory management during worker process termination. When a worker process is shut down, the system attempts to free allocated memory resources, but due to the flawed implementation, this memory can be accessed or reused before proper deallocation occurs. Attackers can exploit this condition by crafting malicious web pages that create and destroy worker processes in specific sequences, causing the browser to attempt to access freed memory locations. This can result in memory corruption that manifests as browser crashes, application instability, and potentially more severe consequences depending on the execution context. The vulnerability demonstrates characteristics consistent with the ATT&CK technique T1059.007 for Command and Scripting Interpreter: JavaScript, where attackers leverage browser-based scripting to execute malicious code that exploits memory management flaws.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it could potentially enable remote code execution or privilege escalation depending on the system configuration and exploitation vector. When exploited successfully, the use-after-free condition can cause the Chrome browser to crash repeatedly, leading to persistent denial of service for the affected user. More concerning is the potential for attackers to leverage this flaw to execute arbitrary code within the browser context, potentially leading to full system compromise. The vulnerability affects all users of the affected Chrome versions regardless of their security awareness or system configuration, making it particularly dangerous in enterprise environments where users may encounter malicious web content through various attack vectors including phishing campaigns, compromised websites, or drive-by downloads. Organizations running affected browser versions face significant risk as this vulnerability can be exploited without user interaction, making it particularly stealthy and dangerous.
Mitigation strategies for CVE-2013-6646 primarily focus on immediate browser updates to patched versions that address the memory management flaw in Web Workers implementation. System administrators should prioritize deployment of Chrome updates across all managed devices, ensuring that Windows, Mac OS X, and Linux systems receive the appropriate version patches. Additionally, implementing network-level security controls such as web application firewalls and content filtering solutions can help reduce exposure to malicious web content that might exploit this vulnerability. Browser hardening measures including disabling unnecessary JavaScript features, implementing strict Content Security Policies, and using sandboxing technologies can provide additional defense-in-depth layers. Organizations should also consider deploying automated patch management solutions to ensure timely remediation of similar vulnerabilities in the future. The vulnerability serves as a reminder of the critical importance of keeping browser software current, as Web Workers are commonly used in modern web applications and their exploitation can have far-reaching consequences for both individual users and enterprise environments.