CVE-2016-4414 in Quassel
Summary
by MITRE
The onReadyRead function in core/coreauthhandler.cpp in Quassel before 0.12.4 allows remote attackers to cause a denial of service (NULL pointer dereference and crash) via invalid handshake data.
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Analysis
by VulDB Data Team • 10/01/2024
The vulnerability identified as CVE-2016-4414 resides within the Quassel IRC client's core authentication handler component, specifically in the onReadyRead function located in core/coreauthhandler.cpp. This flaw represents a classic null pointer dereference vulnerability that can be exploited by remote attackers to trigger a denial of service condition. Quassel is a distributed IRC client that allows users to connect to IRC networks through a centralized core server, making it a critical component in IRC communication infrastructure. The vulnerability affects Quassel versions prior to 0.12.4, indicating that this was a known issue that required a specific patch to resolve the underlying security flaw.
The technical nature of this vulnerability stems from inadequate input validation within the authentication handshake process. When the onReadyRead function processes incoming data during the initial connection handshake, it fails to properly validate the structure and content of the handshake data before attempting to access pointers within the parsed data structure. This lack of proper validation leads to a scenario where maliciously crafted handshake data can cause the application to attempt to dereference a NULL pointer, resulting in an immediate crash of the Quassel core process. The vulnerability operates at the protocol level during the authentication phase, making it particularly dangerous as it can be triggered without requiring authentication or prior access to the system.
The operational impact of CVE-2016-4414 extends beyond simple service disruption, as it can be leveraged by attackers to maintain persistent availability issues within IRC networks that rely on Quassel infrastructure. This type of denial of service attack can be particularly damaging in environments where Quassel serves as a critical communication platform for collaborative work, community management, or organizational chat systems. The vulnerability aligns with CWE-476 which specifically addresses NULL pointer dereference conditions, and represents a common pattern in network service applications where insufficient input validation leads to crashes. From an adversary perspective, this vulnerability maps to ATT&CK technique T1499.004 which involves network denial of service attacks, making it a valuable target for attackers seeking to disrupt communication services.
Mitigation strategies for CVE-2016-4414 focus primarily on upgrading to Quassel version 0.12.4 or later, which includes the necessary patches to properly validate handshake data and prevent null pointer dereference conditions. System administrators should also implement network monitoring to detect unusual connection patterns that might indicate exploitation attempts, though the nature of the vulnerability makes detection challenging since it occurs during the initial handshake phase. Additionally, organizations should consider implementing rate limiting on connection attempts and validating all incoming data through proper input sanitization techniques to prevent similar vulnerabilities from manifesting in other components of the system. The fix implemented in version 0.12.4 demonstrates the importance of proper error handling and input validation in authentication protocols, as it ensures that malformed handshake data cannot cause application crashes regardless of its structure or content.