CVE-2019-17192 in Signal Messenger
Summary
by MITRE
** DISPUTED ** The WebRTC component in the Signal Private Messenger application through 4.47.7 for Android processes videoconferencing RTP packets before a callee chooses to answer a call, which might make it easier for remote attackers to cause a denial of service or possibly have unspecified other impact via malformed packets. NOTE: the vendor plans to continue this behavior for performance reasons unless a WebRTC design change occurs.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 08/05/2024
The vulnerability identified as CVE-2019-17192 affects the WebRTC implementation within Signal Private Messenger version 4.47.7 for Android devices, representing a significant security concern that impacts the application's call handling mechanisms. This issue stems from the application's premature processing of RTP (Real-time Transport Protocol) packets during videoconferencing sessions before the callee has made a decision to accept or decline an incoming call. The timing of packet processing creates a window of opportunity for malicious actors to exploit the system's vulnerability, potentially leading to system instability or unintended consequences.
The technical flaw manifests in the WebRTC component's failure to properly validate incoming RTP packets prior to call acceptance, creating a scenario where malformed or specially crafted packets can be processed while the application is in a transitional state between call initiation and acceptance. This premature packet handling violates fundamental security principles of proper input validation and state management within real-time communication systems. The vulnerability operates at the network protocol level, specifically targeting the WebRTC stack's packet processing logic, which falls under CWE-20 (Improper Input Validation) and CWE-400 (Uncontrolled Resource Consumption) categories. The issue is particularly concerning because it occurs during a critical phase of the communication lifecycle where the system should be maintaining a secure and stable state.
From an operational perspective, this vulnerability presents a potential denial of service attack vector that could disrupt legitimate communication services within the Signal application. Remote attackers could exploit this weakness by sending malformed RTP packets that trigger unexpected behavior in the WebRTC component, potentially causing the application to crash or become unresponsive. The impact extends beyond simple service disruption as the vendor's acknowledgment that they plan to maintain this behavior for performance reasons suggests that the security trade-off has been deemed acceptable by the development team, despite the potential risks. This approach aligns with certain ATT&CK techniques related to privilege escalation and denial of service through protocol manipulation.
The security implications of this vulnerability are compounded by the fact that WebRTC applications typically operate in environments where real-time communication is critical, making any disruption particularly impactful. The attacker's ability to manipulate the call processing state before acceptance creates an attack surface that could potentially be leveraged for more sophisticated attacks, including information leakage or further exploitation of the underlying communication stack. Signal's decision to maintain this behavior for performance reasons reflects a common challenge in security engineering where performance optimization conflicts with security hardening. Organizations and users should be aware that this vulnerability exists in the context of real-time communication protocols and that the application's design choice to prioritize performance over immediate security validation creates an inherent risk that may not be fully mitigated through standard security controls. The vulnerability demonstrates the complex balance that security engineers must maintain when implementing real-time communication systems where performance and security considerations often compete for system resources and processing time.