CVE-2011-3380 in Openswan
Summary
by MITRE
Openswan 2.6.29 through 2.6.35 allows remote attackers to cause a denial of service (NULL pointer dereference and pluto IKE daemon crash) via an ISAKMP message with an invalid KEY_LENGTH attribute, which is not properly handled by the error handling function.
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Analysis
by VulDB Data Team • 01/06/2025
The vulnerability identified as CVE-2011-3380 affects Openswan implementations version 2.6.29 through 2.6.35, representing a critical denial of service weakness that can be exploited remotely by attackers to crash the pluto IKE daemon. This vulnerability stems from improper handling of ISAKMP messages containing invalid KEY_LENGTH attributes, creating a scenario where the system encounters a NULL pointer dereference during error processing. The flaw specifically impacts the IKE daemon component responsible for managing Internet Key Exchange protocol operations, which forms the foundation of secure communication channels in IPsec implementations.
The technical exploitation of this vulnerability occurs when an attacker crafts a malicious ISAKMP message with an invalid KEY_LENGTH attribute value that falls outside the expected parameter range. When the pluto daemon processes this malformed message, it fails to properly validate the attribute before attempting to reference it, leading to a NULL pointer dereference in the error handling code path. This type of vulnerability falls under CWE-476 which specifically addresses NULL pointer dereference conditions, and represents a classic example of inadequate input validation and error handling in network protocol implementations. The vulnerability manifests as an immediate system crash of the pluto daemon, effectively rendering the IPsec service unavailable and causing denial of service for legitimate users.
From an operational perspective, this vulnerability presents significant risks to network security infrastructure as it allows remote attackers to disrupt critical security services without requiring authentication or privileged access. The impact extends beyond simple service disruption since the pluto daemon is responsible for establishing and maintaining secure IPsec tunnels, meaning that successful exploitation can compromise the entire IPsec security framework. The vulnerability affects systems implementing Openswan as an IPsec implementation, which was widely deployed in enterprise networks, VPN solutions, and security appliances. The attack vector requires only network access to send the malformed ISAKMP message, making it particularly dangerous as it can be exploited from external networks without requiring physical access or insider knowledge.
Security practitioners should implement immediate mitigations including upgrading to Openswan versions 2.6.36 or later where this vulnerability has been patched, as well as deploying network access controls to restrict ISAKMP traffic to trusted sources only. The patch typically addresses the issue by implementing proper validation of KEY_LENGTH attributes before attempting to process them, preventing the NULL pointer dereference condition. Additionally, monitoring and logging should be enhanced to detect unusual ISAKMP message patterns that may indicate attempted exploitation. Organizations should also consider implementing intrusion detection systems capable of identifying malformed ISAKMP traffic patterns and deploying network segmentation to limit the potential impact of such attacks. This vulnerability aligns with ATT&CK technique T1499 which covers network denial of service attacks, and represents a common attack pattern targeting the foundational components of network security infrastructure. The incident response plan should include procedures for rapid detection and recovery of compromised IKE daemon services, as well as regular testing of failover mechanisms to ensure continued availability of secure communication channels.