CVE-2008-1748 in Unified Communications Manager
Summary
by MITRE
Cisco Unified Communications Manager 4.1 before 4.1(3)SR7, 4.2 before 4.2(3)SR4, 4.3 before 4.3(2), 5.x before 5.1(3), and 6.x before 6.1(1) does not properly validate SIP URLs, which allows remote attackers to cause a denial of service (service interruption) via a SIP INVITE message, aka Bug ID CSCsl22355.
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Analysis
by VulDB Data Team • 08/10/2019
Cisco Unified Communications Manager suffers from a critical vulnerability in its Session Initiation Protocol implementation where it fails to properly validate SIP Uniform Resource Locators. This weakness exists across multiple versions including 4.1 before 4.1(3)SR7, 4.2 before 4.2(3)SR4, 4.3 before 4.3(2), 5.x before 5.1(3), and 6.x before 6.1(1). The vulnerability stems from inadequate input validation mechanisms within the SIP INVITE message processing pipeline, allowing malicious actors to craft specially formatted URLs that exploit the system's validation logic.
The technical flaw manifests when the system receives a SIP INVITE message containing malformed or specially crafted URL parameters that bypass normal validation checks. This occurs due to insufficient sanitization of the SIP URL components, particularly in the user portion of the URI where attackers can inject sequences that cause the application to enter an invalid state. The vulnerability maps to CWE-20, which describes improper input validation, and specifically relates to CWE-770, which addresses allocation of resources without limits or with inadequate limits. The attack vector involves sending a crafted SIP INVITE message to the target system, which then processes the malformed URL without proper bounds checking.
The operational impact of this vulnerability is significant as it enables remote attackers to perform denial of service attacks against the Cisco Unified Communications Manager services. When the system processes the malicious SIP INVITE message, it can cause the application to crash or enter a state where it cannot properly handle subsequent legitimate SIP traffic. This service interruption affects the entire communication infrastructure managed by the affected system, potentially disrupting voice and video conferencing capabilities for all users relying on the unified communications platform. The vulnerability affects the availability aspect of the CIA triad and can be classified under the ATT&CK technique T1499.1 for Network Denial of Service.
Mitigation strategies should focus on applying the vendor-provided security patches and updates, specifically targeting the versions mentioned in the advisory. Organizations should also implement network segmentation to limit access to SIP ports and consider deploying intrusion detection systems that can identify and block malformed SIP traffic patterns. The recommended approach includes upgrading to patched versions of Cisco Unified Communications Manager, implementing proper SIP URL validation at network boundaries, and monitoring for suspicious SIP traffic patterns. Additionally, administrators should configure proper access controls to limit which systems can send SIP INVITE messages to the affected components. The vulnerability demonstrates the importance of robust input validation in communication protocols and highlights the need for comprehensive testing of edge cases in real-time communication systems.