CVE-2013-1137 in Unified Presence Server
Summary
by MITRE
Cisco Unified Presence Server (CUPS) 8.6, 9.0, and 9.1 before 9.1.1 allows remote attackers to cause a denial of service (CPU consumption) via crafted packets to the SIP TCP port, aka Bug ID CSCua89930.
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Analysis
by VulDB Data Team • 12/29/2021
The vulnerability identified as CVE-2013-1137 affects Cisco Unified Presence Server versions 8.6, 9.0, and 9.1 before 9.1.1, representing a significant denial of service weakness that can be exploited remotely. This vulnerability specifically targets the SIP TCP port functionality within the Cisco Unified Presence Server implementation, creating a condition where maliciously crafted network packets can trigger excessive cpu utilization on the affected system. The vulnerability is classified under the Common Weakness Enumeration as CWE-400, which encompasses weaknesses related to resource exhaustion, making it a critical concern for network infrastructure security. The bug ID CSCua89930 further identifies this specific flaw within Cisco's internal tracking systems, highlighting the vendor's recognition of its severity and impact on system availability.
The technical flaw manifests when the Cisco Unified Presence Server fails to properly validate incoming SIP TCP packets, allowing attackers to send malformed or specially crafted packets that cause the system to consume excessive cpu resources during packet processing. This occurs because the server does not implement adequate input validation mechanisms to filter out malformed packets before attempting to process them through the SIP protocol stack. The vulnerability exploits a fundamental weakness in the server's packet handling routines where insufficient sanitization of incoming network traffic leads to resource consumption that can escalate to complete system denial of service. The attack vector requires only network access to the targeted SIP TCP port, making it particularly dangerous as it can be executed from anywhere on the network without requiring authentication or privileged access.
The operational impact of this vulnerability extends beyond simple service disruption, as it can render the Cisco Unified Presence Server completely non-functional and unable to provide presence services to users. This affects organizations that rely on presence information for communication systems, potentially disrupting collaboration tools, instant messaging services, and unified communications workflows. The sustained high cpu consumption can lead to system instability, application crashes, and complete service outages that may last until the affected system is manually restarted or the malicious traffic is filtered. According to ATT&CK framework category T1499, this vulnerability represents a resource exhaustion attack that can be classified as a denial of service condition, impacting the availability aspect of the CIA triad. Organizations may experience significant downtime and productivity loss as users lose access to presence information and communication services.
Mitigation strategies for CVE-2013-1137 should prioritize immediate patching of affected Cisco Unified Presence Server installations to version 9.1.1 or later, which contains the necessary fixes to address the packet validation weaknesses. Network administrators should implement firewall rules and access control lists to restrict access to the SIP TCP port from trusted sources only, reducing the attack surface for potential exploitation. Additionally, implementing network monitoring and intrusion detection systems can help identify unusual cpu utilization patterns and suspicious packet traffic that may indicate exploitation attempts. Cisco recommends deploying the latest security patches and updates as part of their regular maintenance procedures to protect against similar vulnerabilities. Organizations should also consider implementing rate limiting and packet filtering mechanisms at network boundaries to prevent malformed packets from reaching the vulnerable server components, providing an additional layer of defense against resource exhaustion attacks.