CVE-2014-2891 in strongSwan
Summary
by MITRE
strongSwan before 5.1.2 allows remote attackers to cause a denial of service (NULL pointer dereference and IKE daemon crash) via a crafted ID_DER_ASN1_DN ID payload.
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Analysis
by VulDB Data Team • 06/19/2021
The vulnerability identified as CVE-2014-2891 represents a critical denial of service weakness in strongSwan versions prior to 5.1.2, specifically affecting the IKE daemon responsible for establishing secure IPsec connections. This flaw manifests through a NULL pointer dereference condition that occurs when processing specially crafted ID_DER_ASN1_DN identifier payloads within the Internet Key Exchange protocol implementation. The issue stems from inadequate input validation mechanisms within the strongSwan cryptographic framework, which fails to properly handle malformed ASN.1 distinguished name structures during IKE negotiation processes. Such malformed payloads can be transmitted by remote attackers to initiate the vulnerable code path that leads to daemon termination and system unavailability.
The technical exploitation of this vulnerability requires an attacker to construct and send a malicious ID payload containing malformed DER-encoded ASN.1 distinguished name data to a targeted strongSwan daemon. When the daemon attempts to process this crafted payload, it encounters a NULL pointer reference during parsing operations, resulting in an immediate crash of the IKE daemon service. This behavior aligns with CWE-476 which categorizes NULL pointer dereference vulnerabilities as critical weaknesses that can lead to system instability and service disruption. The vulnerability affects the core IKEv2 protocol implementation within strongSwan, specifically impacting the identity management subsystem where peer identities are validated and processed during security association establishment. The daemon crash represents a complete denial of service condition that prevents legitimate users from establishing secure connections through the affected system.
The operational impact of CVE-2014-2891 extends beyond simple service disruption to encompass broader network security implications for organizations relying on strongSwan for IPsec VPN connectivity. When the IKE daemon crashes, all active and pending IPsec connections are terminated, forcing network administrators to manually restart services and potentially disrupting business operations that depend on secure remote access. The vulnerability can be exploited remotely without authentication requirements, making it particularly dangerous in environments where strongSwan serves as a gateway for remote workforce access or site-to-site connectivity. This weakness directly relates to ATT&CK technique T1499.004 which involves network disruption attacks targeting network infrastructure components. Organizations using vulnerable strongSwan implementations face potential exposure to extended service outages, increased administrative overhead for incident response, and potential business continuity impacts when the vulnerability is successfully exploited.
Mitigation strategies for CVE-2014-2891 primarily focus on immediate patch deployment to upgrade strongSwan installations to version 5.1.2 or later, which contains the necessary code fixes to properly validate and handle malformed ASN.1 distinguished name payloads. Network administrators should implement monitoring solutions to detect unusual patterns of IKE daemon crashes or connection failures that may indicate exploitation attempts. Additional defensive measures include configuring firewalls to restrict access to IKE ports to trusted sources only, implementing rate limiting on IKE negotiation requests, and establishing automated service restart procedures to minimize downtime. Organizations should also conduct comprehensive vulnerability assessments to identify all systems running vulnerable strongSwan versions and prioritize remediation efforts based on risk exposure. The fix implemented in strongSwan 5.1.2 addresses the root cause by introducing proper NULL pointer checks and input validation mechanisms within the identity payload processing code, thereby preventing the crash condition from occurring when malformed payloads are received.