CVE-2005-4570 in Internet Key Exchange
Summary
by MITRE
The Internet Key Exchange version 1 (IKEv1) implementations in Fortinet FortiOS 2.50, 2.80 and 3.0, FortiClient 2.0,; and FortiManager 2.80 and 3.0 allow remote attackers to cause a denial of service (termination of a process that is automatically restarted) via IKE packets with invalid values of certain IPSec attributes, as demonstrated by the PROTOS ISAKMP Test Suite for IKEv1. NOTE: due to the lack of details in the vendor advisory, it is unclear which of CVE-2005-3666, CVE-2005-3667, and/or CVE-2005-3668 this issue applies to.
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Analysis
by VulDB Data Team • 08/02/2017
The vulnerability described in CVE-2005-4570 represents a critical denial of service weakness affecting Internet Key Exchange version 1 implementations within Fortinet's FortiOS and related security products. This flaw specifically targets the processing of IKE packets containing malformed IPSec attribute values, creating a scenario where legitimate network traffic can trigger system instability and service interruption. The affected versions include FortiOS 2.50, 2.80, and 3.0, along with FortiClient 2.0 and FortiManager 2.80 and 3.0, indicating a widespread impact across Fortinet's security infrastructure products. The vulnerability manifests when the system encounters invalid IPSec attributes within IKE packets, causing processes to terminate unexpectedly and subsequently restart automatically, leading to sustained disruption of security services.
The technical nature of this vulnerability aligns with CWE-122, which describes buffer overflow conditions that can occur when systems fail to properly validate input data. The flaw operates at the protocol level where IKEv1 implementations lack adequate validation mechanisms for IPSec attributes, allowing attackers to craft malicious packets that exploit parsing weaknesses in the security software. This type of vulnerability falls under the ATT&CK technique T1499.004, specifically targeting network denial of service through protocol manipulation. The PROTOS ISAKMP Test Suite for IKEv1 demonstrates how this vulnerability can be exploited in practice, showing that legitimate testing tools can trigger the denial of service condition, which means the flaw is not merely theoretical but has been validated in controlled environments.
The operational impact of this vulnerability extends beyond simple service interruption, as it compromises the reliability and availability of critical network security infrastructure. When security processes terminate and automatically restart, network communications may experience intermittent disruptions that can go unnoticed but ultimately undermine the security posture of protected networks. Organizations relying on Fortinet products for IPSec VPN services and security policy enforcement face significant risk, as attackers could systematically target these systems to create ongoing service degradation. The automatic restart mechanism, while designed to maintain availability, actually compounds the problem by creating a cycle of service interruption and recovery that can overwhelm system resources and potentially mask more serious underlying issues.
Mitigation strategies for this vulnerability should focus on implementing network segmentation and access controls to limit exposure to untrusted networks. Organizations should consider deploying intrusion detection systems that can identify and block malformed IKE packets before they reach vulnerable systems. The most effective long-term solution involves upgrading to patched versions of Fortinet products that properly validate IPSec attributes and implement robust error handling for malformed input data. Network administrators should also implement monitoring solutions to detect unusual process termination patterns and automatic restart cycles that may indicate exploitation attempts. Additionally, organizations should conduct regular security assessments of their IPSec implementations and maintain updated threat intelligence to identify potential exploitation patterns. Given the nature of the vulnerability, implementing proper input validation and boundary checking mechanisms within the IKEv1 implementation would address the root cause while maintaining compatibility with legitimate network traffic.