CVE-2017-11185 in strongSwan
Summary
by MITRE
The gmp plugin in strongSwan before 5.6.0 allows remote attackers to cause a denial of service (NULL pointer dereference and daemon crash) via a crafted RSA signature.
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Analysis
by VulDB Data Team • 12/04/2025
The vulnerability identified as CVE-2017-11185 resides within the gmp plugin of strongSwan, a widely deployed open source IPsec implementation that serves as a cornerstone for secure network communications. This flaw represents a critical denial of service vulnerability that can be exploited by remote attackers to crash the strongSwan daemon, effectively disrupting network security services. The vulnerability specifically affects versions prior to 5.6.0, indicating that organizations running older iterations of this security software remain at significant risk.
The technical mechanism behind this vulnerability involves a NULL pointer dereference that occurs when processing crafted RSA signatures within the gmp plugin. This type of flaw falls under the category of improper input validation, where the software fails to properly validate or sanitize cryptographic signatures before attempting to process them. When a maliciously crafted RSA signature is received, the gmp plugin does not adequately check for null or invalid pointer references in the signature processing pipeline, leading to an abrupt system crash. The vulnerability operates at the cryptographic processing layer of the IPsec implementation, where signature verification is a critical component of authentication and integrity verification.
From an operational perspective, the impact of this vulnerability extends beyond simple service disruption. The strongSwan daemon serves as a fundamental component for establishing secure VPN connections, enabling encrypted communications between remote users, devices, and network infrastructure. When the daemon crashes due to this NULL pointer dereference, it results in complete loss of IPsec connectivity for all affected systems, potentially compromising network security and disrupting business operations. The remote exploitability means that attackers can trigger this vulnerability without requiring local access or authentication, making it particularly dangerous in network environments where strongSwan is deployed.
The vulnerability demonstrates characteristics consistent with CWE-476, which describes NULL pointer dereference issues in software implementations. This weakness allows attackers to manipulate the program flow and cause crashes that can be leveraged for denial of service attacks. The specific exploitation pattern aligns with ATT&CK technique T1499.004, which covers network disruption through service availability attacks, where attackers target critical infrastructure services to prevent legitimate access. Organizations utilizing strongSwan in production environments must understand that this vulnerability can be weaponized to create widespread service outages that affect multiple network connections simultaneously.
Organizations should implement immediate mitigation strategies including upgrading to strongSwan version 5.6.0 or later, which contains the necessary patches to address this vulnerability. Additionally, network administrators should consider implementing monitoring solutions to detect anomalous signature processing patterns that might indicate exploitation attempts. The fix typically involves adding proper null pointer checks within the gmp plugin's signature validation routines to prevent the daemon from crashing when malformed RSA signatures are encountered. Regular security assessments and vulnerability scanning should be conducted to identify other potential weaknesses in the IPsec infrastructure that might be exploited in conjunction with this vulnerability.