CVE-2016-5391 in Libreswan
Summary
by MITRE
libreswan before 3.18 allows remote attackers to cause a denial of service (NULL pointer dereference and pluto daemon restart).
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Analysis
by VulDB Data Team • 12/08/2022
The vulnerability identified as CVE-2016-5391 affects libreswan versions prior to 3.18, presenting a significant security risk through a null pointer dereference flaw that can be exploited remotely to trigger a denial of service condition. This vulnerability specifically targets the pluto daemon component of libreswan, which serves as the key management and policy daemon for ipsec connections within the system. The flaw stems from inadequate input validation and error handling within the daemon's processing logic, creating a condition where maliciously crafted network packets can cause the pluto service to crash and restart automatically.
The technical implementation of this vulnerability involves a null pointer dereference occurring during the processing of certain ipsec protocol messages. When the pluto daemon receives specially crafted packets that exploit this weakness, the software attempts to access a null memory pointer, resulting in an immediate crash of the daemon process. This crash forces the daemon to restart automatically as part of its normal recovery mechanisms, creating a denial of service condition that disrupts all active ipsec connections and prevents legitimate network communication from functioning properly. The vulnerability is particularly dangerous because it requires no authentication or elevated privileges to exploit, making it accessible to any remote attacker with network access to the affected system.
From an operational impact perspective, this vulnerability presents a severe threat to network infrastructure security as it can be leveraged to disrupt critical ipsec-based communications without requiring any specialized access credentials. The automatic restart of the pluto daemon creates a cascading effect that can affect multiple network connections simultaneously, potentially compromising network availability for organizations relying on ipsec tunnels for secure communications. The vulnerability aligns with CWE-476 which specifically addresses null pointer dereference conditions, and can be mapped to ATT&CK technique T1499.004 which covers network denial of service attacks. Organizations using vulnerable libreswan versions face potential disruption of secure network communications, including vpn connections, site-to-site ipsec tunnels, and other ipsec-based security protocols that depend on the pluto daemon for proper operation.
The recommended mitigation strategy involves immediate deployment of libreswan version 3.18 or later, which includes patches specifically addressing this null pointer dereference vulnerability. System administrators should conduct thorough vulnerability assessments to identify all systems running affected libreswan versions and implement patch management procedures to ensure timely updates. Additionally, network monitoring should be enhanced to detect unusual daemon restart patterns that may indicate exploitation attempts. Organizations should also consider implementing network segmentation and access controls to limit exposure of vulnerable systems to untrusted networks, while maintaining regular security audits to verify that all ipsec implementations are properly updated and configured according to security best practices.