CVE-2009-1632 in Ipsec-tools
Summary
by MITRE
Multiple memory leaks in Ipsec-tools before 0.7.2 allow remote attackers to cause a denial of service (memory consumption) via vectors involving (1) signature verification during user authentication with X.509 certificates, related to the eay_check_x509sign function in src/racoon/crypto_openssl.c; and (2) the NAT-Traversal (aka NAT-T) keepalive implementation, related to src/racoon/nattraversal.c.
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Analysis
by VulDB Data Team • 09/04/2019
The vulnerability described in CVE-2009-1632 represents a significant security flaw in ipsec-tools version 0.7.1 and earlier, affecting the secure internet protocol implementation used for virtual private network communications. This vulnerability manifests through multiple memory leak conditions that can be exploited remotely to consume system resources and potentially cause denial of service conditions. The issue specifically targets the cryptographic operations and network traversal mechanisms within the ipsec-tools framework, which are critical components for establishing secure communications between network endpoints.
The first memory leak occurs during the X.509 certificate signature verification process when user authentication takes place, specifically within the eay_check_x509sign function located in src/racoon/crypto_openssl.c. This function handles the cryptographic verification of digital signatures contained within X.509 certificates used for authentication purposes in ipsec connections. When remote attackers craft malicious certificate requests or authentication attempts, the function fails to properly release allocated memory resources, leading to gradual memory consumption that can eventually exhaust available system memory. This vulnerability aligns with CWE-401 which identifies improper management of memory allocation and deallocation as a critical weakness in software security.
The second memory leak is found in the NAT-Traversal (NAT-T) keepalive implementation, specifically within the src/racoon/nattraversal.c file. NAT-T functionality is essential for maintaining ipsec connections when network address translation occurs between communicating parties. The keepalive mechanism periodically sends packets to verify connection integrity and maintain state in NAT environments. However, the implementation contains memory management flaws where allocated resources are not properly freed during the keepalive packet processing, resulting in progressive memory consumption over time. This aspect of the vulnerability relates to the broader category of resource management issues that can be exploited to cause system instability.
The operational impact of these memory leaks is substantial, as they can be exploited remotely without requiring authentication or special privileges. An attacker can repeatedly trigger either the certificate verification process or the NAT-T keepalive functionality to gradually consume system memory, eventually leading to denial of service conditions where legitimate users cannot establish new ipsec connections or existing connections become unstable. The vulnerability affects systems that rely on ipsec-tools for secure communications, particularly those operating in environments where NAT traversal is required or where X.509 certificate authentication is used. This makes the impact widespread across enterprise networks, cloud deployments, and any infrastructure requiring secure remote access capabilities.
From an attack perspective, these vulnerabilities align with the MITRE ATT&CK framework under the T1499 technique category for resource exhaustion, specifically targeting system resources through memory consumption. The attack can be executed from any remote location with network access to the affected ipsec-tools service, making it particularly dangerous in network environments where such services are exposed to external traffic. The exploitation requires minimal skill and can be automated, making it a preferred method for attackers seeking to disrupt network services without detection. Organizations using ipsec-tools versions prior to 0.7.2 should consider these vulnerabilities as high-risk due to their potential for causing widespread service disruption.
The recommended mitigation strategy involves upgrading to ipsec-tools version 0.7.2 or later, which contains the necessary patches to address both memory leak conditions. System administrators should also implement monitoring solutions to detect unusual memory consumption patterns that might indicate exploitation attempts. Additional defensive measures include implementing network segmentation to limit exposure of ipsec services, configuring firewalls to restrict access to these services, and establishing baseline memory usage monitoring to quickly identify potential exploitation activities. The vulnerability demonstrates the critical importance of proper memory management in security-critical software components and serves as a reminder of the need for regular security updates and vulnerability assessments in network infrastructure software.