CVE-2016-1970 in Firefox
Summary
by MITRE
Integer underflow in the srtp_unprotect function in the WebRTC implementation in Mozilla Firefox before 45.0 on Windows might allow remote attackers to cause a denial of service (memory corruption) or possibly have unspecified other impact via unknown vectors.
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Analysis
by VulDB Data Team • 07/09/2022
The vulnerability identified as CVE-2016-1970 represents a critical integer underflow condition within the Secure Real-time Transport Protocol (SRTP) implementation of Mozilla Firefox's WebRTC framework. This flaw exists specifically within the srtp_unprotect function, which is responsible for processing incoming SRTP packets and verifying their integrity and authenticity. The issue affects Firefox versions prior to 45.0 on Windows operating systems, making it particularly concerning given the widespread use of Firefox as a web browser and the prevalence of Windows environments. The integer underflow occurs when the function processes certain malformed SRTP packets that contain unexpected sequence number values, leading to improper memory calculations during packet validation.
The technical exploitation of this vulnerability stems from the improper handling of unsigned integer arithmetic within the SRTP protection mechanism. When the srtp_unprotect function encounters SRTP packets with sequence numbers that cause arithmetic underflow conditions, the resulting negative values can corrupt memory structures or cause unexpected program behavior. This type of vulnerability falls under the CWE-191 category of Integer Underflow (Wrap or Wraparound), which is classified as a common weakness in software development practices that can lead to serious security implications. The vulnerability's impact extends beyond simple denial of service, as the memory corruption could potentially be leveraged for more sophisticated attacks depending on the execution context and memory layout.
From an operational perspective, this vulnerability creates significant risk for Firefox users who may encounter maliciously crafted WebRTC sessions or media streams. Attackers could potentially exploit this weakness by initiating WebRTC connections with specially crafted SRTP packets that trigger the integer underflow condition. The attack surface is particularly relevant in environments where Firefox is used for video conferencing, real-time communication, or any application that relies on WebRTC functionality. The vulnerability's potential for unspecified other impacts suggests that depending on the system configuration and memory state, attackers might be able to achieve more severe consequences beyond simple service disruption, potentially including arbitrary code execution or privilege escalation scenarios.
The mitigation strategy for CVE-2016-1970 involves immediate deployment of Firefox version 45.0 or later, which contains the necessary patches to address the integer underflow condition in the SRTP implementation. Organizations should prioritize updating their Firefox installations across all Windows environments to prevent exploitation. Additionally, network administrators should consider implementing monitoring for unusual WebRTC traffic patterns that might indicate exploitation attempts. The vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as attackers might attempt to leverage such memory corruption vulnerabilities to execute malicious code. Security teams should also review their incident response procedures to ensure proper handling of potential exploitation attempts, as the vulnerability's impact can manifest in both denial of service and potential code execution scenarios. The fix implemented by Mozilla addresses the root cause by adding proper bounds checking and validation of sequence number values during SRTP packet processing, preventing the arithmetic underflow condition that led to memory corruption.