CVE-2008-5014 in Firefox
Summary
by MITRE
jslock.cpp in Mozilla Firefox 3.x before 3.0.2, Firefox 2.x before 2.0.0.18, Thunderbird 2.x before 2.0.0.18, and SeaMonkey 1.x before 1.1.13 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code by modifying the window.__proto__.__proto__ object in a way that causes a lock on a non-native object, which triggers an assertion failure related to the OBJ_IS_NATIVE function.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 08/20/2019
This vulnerability resides in the JavaScript engine of Mozilla Firefox and related applications, specifically within the jslock.cpp file that manages object locking mechanisms. The flaw manifests when remote attackers manipulate the window._proto_._proto_ object structure to create a scenario where a lock is applied to a non-native object, triggering an assertion failure that is tied to the OBJ_IS_NATIVE function. This represents a classic case of improper input validation and object handling in the JavaScript engine's locking subsystem.
The technical implementation of this vulnerability exploits the object prototype chain manipulation capabilities available to web content. By accessing and modifying the _proto_ properties of the window object, attackers can construct malicious object hierarchies that bypass normal object type checks. The assertion failure occurs because the system attempts to perform a lock operation on an object that does not meet the expected native object criteria, causing the JavaScript engine to crash or potentially execute arbitrary code. This vulnerability operates at the intersection of JavaScript engine security and memory management, where improper object validation leads to critical system instability.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enabling remote code execution, making it particularly dangerous for web browsers that process untrusted content. When exploited, the vulnerability can cause browser crashes that may be leveraged for more sophisticated attacks, including privilege escalation or persistent compromise of user systems. The attack vector requires only the ability to execute JavaScript code within the browser context, which is trivially achieved through malicious websites, email attachments, or compromised web services. This makes the vulnerability highly exploitable in real-world scenarios where users browse the internet or receive email content.
Mitigation strategies for this vulnerability involve immediate patching of affected browser versions, as the original vulnerability was addressed through code modifications that properly validate object types before attempting lock operations. Security administrators should implement comprehensive browser update policies and consider deploying additional security layers such as content security policies and sandboxing mechanisms. The vulnerability aligns with CWE-119 Improper Access to Memory and CWE-248 Uncaught Exception categories, while also mapping to ATT&CK technique T1059.007 for execution through JavaScript and T1499.004 for denial of service. Organizations should also consider browser hardening measures, including disabling unnecessary JavaScript features and implementing strict security policies to limit the attack surface available to potential exploit attempts.