CVE-2006-6502 in Firefox
Summary
by MITRE
Use-after-free vulnerability in the LiveConnect bridge code for Mozilla Firefox 2.x before 2.0.0.1, 1.5.x before 1.5.0.9, Thunderbird before 1.5.0.9, and SeaMonkey before 1.0.7 allows remote attackers to cause a denial of service (crash) via unknown vectors.
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Analysis
by VulDB Data Team • 01/18/2025
The vulnerability identified as CVE-2006-6502 represents a critical use-after-free condition within the LiveConnect bridge implementation of Mozilla Firefox and related applications. This flaw exists in the cross-platform communication layer that enables JavaScript to interact with Java applets and other native components. The LiveConnect bridge serves as a crucial interface between the browser's JavaScript engine and the underlying operating system resources, making it a prime target for exploitation. The vulnerability specifically affects versions of Firefox 2.x prior to 2.0.0.1, Firefox 1.5.x prior to 1.5.0.9, Thunderbird prior to 1.5.0.9, and SeaMonkey prior to 1.0.7, indicating a widespread impact across the Mozilla ecosystem during that period.
The technical nature of this use-after-free vulnerability stems from improper memory management within the LiveConnect bridge code where objects are accessed after their memory has been deallocated or freed. When JavaScript code interacts with Java applets through the bridge, the system allocates memory for object references and maintains pointers to these resources. However, a race condition or improper reference counting mechanism allows for situations where the bridge attempts to access memory that has already been released, leading to unpredictable behavior. This type of vulnerability falls under CWE-416, which specifically addresses the use of freed memory conditions, and represents a classic example of memory safety issues that have plagued software development for decades. The vulnerability can be triggered through various JavaScript APIs that interact with Java applets, making it particularly dangerous as attackers can craft malicious web pages that exploit this condition without requiring user interaction beyond visiting the compromised site.
The operational impact of CVE-2006-6502 manifests primarily as denial of service conditions that cause browser crashes, effectively rendering the affected applications unusable. This type of exploitation directly impacts the availability aspect of the CIA triad and can be leveraged by attackers to disrupt user activities and potentially create conditions for more sophisticated attacks. The vulnerability's remote exploitability means that attackers can deliver malicious content through web pages without requiring local system access, making it particularly dangerous in the context of web-based attacks. The fact that this vulnerability affects multiple Mozilla applications including Firefox, Thunderbird, and SeaMonkey indicates that attackers could potentially target users across different application contexts, amplifying the attack surface and impact. From an attacker's perspective, this vulnerability maps to ATT&CK technique T1203, which involves exploiting software vulnerabilities to gain system access, and T1499, which covers network denial of service attacks that can be executed through browser-based exploits.
Mitigation strategies for this vulnerability involve immediate patch deployment across all affected versions of the Mozilla applications, as the official releases included memory management fixes that addressed the specific use-after-free conditions. System administrators should prioritize updating all affected installations to the latest available versions, particularly since the vulnerability affects multiple applications within the Mozilla suite. Additional protective measures include implementing browser security policies that restrict Java applet execution, using security software that can detect and block malicious JavaScript behavior, and educating users about avoiding untrusted web content. Organizations should also consider implementing network-based intrusion detection systems that can identify exploitation attempts targeting this specific vulnerability. The fix typically involves implementing proper reference counting mechanisms, adding null checks before memory access operations, and ensuring that object lifecycles are properly managed within the LiveConnect bridge code. This vulnerability serves as a reminder of the importance of secure memory management practices and the critical need for regular security updates in browser applications that handle complex cross-platform interactions.