CVE-2005-1907 in ISA Server
Summary
by MITRE
The ISA Firewall service in Microsoft Internet Security and Acceleration (ISA) Server 2000 allows remote attackers to cause a denial of service (Wspsrv.exe crash) via a large amount of SecureNAT network traffic.
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Analysis
by VulDB Data Team • 07/12/2019
The vulnerability described in CVE-2005-1907 represents a critical denial of service weakness within Microsoft Internet Security and Acceleration ISA Server 2000. This flaw specifically targets the ISA Firewall service and manifests through the wspsrv.exe process which handles SecureNAT functionality. The vulnerability operates by exploiting the service's inability to properly handle excessive network traffic volumes, leading to system instability and complete service disruption. The attack vector is particularly concerning as it requires only remote access to trigger the denial of service condition, making it accessible to attackers without physical presence or elevated privileges. The SecureNAT implementation within ISA Server 2000 was designed to provide network address translation services for internal clients, but this feature becomes a liability when subjected to excessive traffic patterns.
The technical root cause of this vulnerability stems from inadequate input validation and resource management within the wspsrv.exe component of the ISA Firewall service. When the service receives an excessive volume of SecureNAT network traffic, the memory allocation and processing mechanisms fail to handle the load appropriately, resulting in process termination and system crash. This behavior aligns with CWE-129, which addresses improper validation of length of input buffers, and CWE-770, concerning allocation of resources without limits or throttling. The vulnerability demonstrates poor resource management practices where the system lacks proper traffic rate limiting or buffer size controls that would prevent the wspsrv.exe process from exhausting available system resources. The attack essentially overwhelms the service's capacity to process legitimate network packets, causing it to crash and restart, thereby denying legitimate users access to network services.
The operational impact of CVE-2005-1907 extends beyond simple service disruption to potentially compromise network availability and business continuity. Organizations relying on ISA Server 2000 for their firewall and network security infrastructure face significant operational risks when this vulnerability is exploited. The denial of service condition affects not only the specific SecureNAT functionality but can also impact the overall network infrastructure as the ISA Firewall service becomes unavailable. This vulnerability can be particularly devastating in enterprise environments where ISA Server 2000 serves as a critical network gateway, potentially affecting thousands of users and applications. The attack requires minimal resources and technical expertise to execute, making it attractive to threat actors seeking to disrupt network operations. From an attacker's perspective, this vulnerability maps to ATT&CK technique T1499.004, which covers network disruption through resource exhaustion, and T1566.002, which involves phishing with malicious attachments or links that could be used to deliver traffic patterns that trigger this vulnerability.
Organizations should implement multiple layers of mitigation strategies to address this vulnerability effectively. The most immediate and effective solution involves applying the relevant Microsoft security patches and updates that address the resource management issues within the wspsrv.exe process. Network administrators should also implement traffic monitoring and rate limiting mechanisms to prevent excessive SecureNAT traffic from overwhelming the service. Configuration changes within the ISA Server 2000 environment should include implementing proper bandwidth limits and traffic shaping policies that prevent any single network flow from consuming excessive resources. Additionally, organizations should consider implementing network segmentation and access controls to limit the exposure of ISA Server 2000 to potentially malicious traffic sources. The implementation of intrusion detection systems can help identify unusual traffic patterns that may indicate exploitation attempts. From a compliance perspective, this vulnerability demonstrates the importance of maintaining up-to-date security patches and following secure configuration practices as outlined in industry standards such as NIST SP 800-40 and ISO 27001. Organizations should also conduct regular vulnerability assessments and penetration testing to identify similar resource exhaustion vulnerabilities within their network infrastructure. The long-term solution involves migrating away from unsupported and vulnerable systems like ISA Server 2000 to modern firewall solutions that provide better resource management and security features.