CVE-2013-1676 in Firefox
Summary
by MITRE
The SelectionIterator::GetNextSegment function in Mozilla Firefox before 21.0, Firefox ESR 17.x before 17.0.6, Thunderbird before 17.0.6, and Thunderbird ESR 17.x before 17.0.6 allows remote attackers to execute arbitrary code or cause a denial of service (out-of-bounds read) via unspecified vectors.
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Analysis
by VulDB Data Team • 05/11/2021
The vulnerability identified as CVE-2013-1676 represents a critical out-of-bounds read flaw within the SelectionIterator::GetNextSegment function of Mozilla Firefox and Thunderbird applications. This issue affects multiple versions of the browser and email client, specifically targeting Firefox versions prior to 21.0 and Firefox ESR 17.x versions before 17.0.6, alongside Thunderbird versions before 17.0.6 and Thunderbird ESR 17.x versions before 17.0.6. The flaw manifests as a memory corruption vulnerability that can be exploited remotely, potentially allowing attackers to execute arbitrary code or induce denial of service conditions within affected applications. The vulnerability stems from improper bounds checking within the selection iteration mechanism that processes user interface selections in the application's rendering engine.
The technical implementation of this vulnerability involves the SelectionIterator::GetNextSegment function failing to properly validate array indices or buffer boundaries when processing text selection operations. When a malicious actor crafts specific input or webpage content that triggers this function, the application attempts to read memory locations beyond the allocated buffer boundaries. This out-of-bounds memory access can result in unpredictable behavior including application crashes, memory corruption, or potentially full code execution if the attacker can control the data being read. The vulnerability operates at the intersection of memory safety issues and browser rendering engine flaws, making it particularly dangerous in web browsing contexts where users may encounter malicious content without explicit awareness. According to CWE classification, this vulnerability maps to CWE-125: Out-of-bounds Read, which is categorized as a memory safety issue affecting software systems that process user-supplied data.
The operational impact of CVE-2013-1676 extends significantly beyond simple denial of service conditions, as the vulnerability can be leveraged for remote code execution in targeted attacks. Attackers can craft malicious web pages or email content that when processed by the affected applications triggers the vulnerable code path, potentially leading to complete system compromise. The vulnerability's exploitation potential is heightened by the fact that it affects widely deployed applications including both Firefox browsers and Thunderbird email clients, which are commonly used across enterprise and personal environments. Security researchers have documented that such out-of-bounds read vulnerabilities often serve as initial access vectors in more sophisticated attack chains, where the primary goal may be to establish a foothold for further exploitation or to deliver additional malware payloads. The vulnerability's presence in both regular and extended support release versions indicates a prolonged exposure window, increasing the risk of exploitation in environments where updates are delayed or not applied promptly.
Mitigation strategies for CVE-2013-1676 primarily focus on immediate application updates to patched versions that contain the necessary memory boundary checks and input validation improvements. Organizations should prioritize deployment of Firefox 21.0, Firefox ESR 17.0.6, Thunderbird 17.0.6, and Thunderbird ESR 17.0.6 releases which contain the relevant fixes. Additionally, security teams should implement network-based protections such as web application firewalls and content filtering systems to prevent access to known malicious domains that may attempt to exploit this vulnerability. Browser hardening measures including disabling unnecessary JavaScript features, implementing strict content security policies, and using sandboxing technologies can further reduce the attack surface. The vulnerability's classification under ATT&CK technique T1059.007 (Command and Scripting Interpreter: JavaScript) highlights the importance of monitoring and controlling JavaScript execution in affected applications. Organizations should also conduct regular vulnerability assessments and penetration testing to identify potential exploitation attempts and ensure that all systems are properly patched against this and similar memory safety vulnerabilities.