CVE-2016-1962 in Firefox
Summary
by MITRE
Use-after-free vulnerability in the mozilla::DataChannelConnection::Close function in Mozilla Firefox before 45.0 and Firefox ESR 38.x before 38.7 allows remote attackers to execute arbitrary code by leveraging mishandling of WebRTC data-channel connections.
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Analysis
by VulDB Data Team • 07/09/2022
The vulnerability identified as CVE-2016-1962 represents a critical use-after-free flaw within Mozilla Firefox's WebRTC implementation that could enable remote code execution. This issue affects Firefox versions prior to 45.0 and Firefox ESR 38.x versions before 38.7, making it a significant concern for organizations relying on these browser versions. The vulnerability specifically resides in the mozilla::DataChannelConnection::Close function, which handles the termination of WebRTC data-channel connections. The flaw arises from improper memory management during the closure process of WebRTC data channels, creating opportunities for attackers to manipulate memory references that have already been freed.
The technical nature of this vulnerability aligns with CWE-416, which describes use-after-free conditions where program code attempts to access memory after it has been freed by the system. In the context of Firefox's WebRTC implementation, when a data channel connection is closed, the application fails to properly invalidate references to the connection object before freeing its memory. This creates a window where malicious WebRTC connections can trigger the execution of arbitrary code through controlled memory corruption. Attackers can leverage this by establishing malicious WebRTC connections and then manipulating the connection closure sequence to cause the freed memory to be accessed, potentially leading to code execution.
The operational impact of CVE-2016-1962 extends beyond simple remote code execution, as it represents a sophisticated attack vector that can be exploited through web-based delivery mechanisms. The vulnerability is particularly dangerous because WebRTC functionality is increasingly prevalent in modern web applications, making the attack surface broader than traditional browser exploits. When exploited, this vulnerability allows attackers to execute arbitrary code with the privileges of the browser process, potentially leading to complete system compromise. The attack requires no local privileges and can be delivered through standard web browsing activities, making it highly attractive to threat actors.
Security professionals should prioritize immediate patching of affected Firefox versions to mitigate this vulnerability. The remediation involves updating to Firefox 45.0 or later, or Firefox ESR 38.7 or later, which contain the necessary memory management fixes for the DataChannelConnection::Close function. Organizations should also implement network-level protections such as web application firewalls and content filtering systems to block malicious WebRTC connections. Additionally, browser hardening measures including disabling unnecessary WebRTC features and implementing strict content security policies can provide additional defense-in-depth layers. The vulnerability demonstrates the importance of proper memory management in complex web applications and highlights the need for comprehensive security testing of real-time communication protocols. This issue also relates to ATT&CK technique T1059.007 for Windows Command Shell and T1566 for Phishing, as attackers could leverage the remote code execution capabilities to establish persistent access and deploy additional malicious payloads.