CVE-2016-1350 in Unified Communications Manager
Summary
by MITRE
Cisco IOS 15.3 and 15.4, Cisco IOS XE 3.8 through 3.11, and Cisco Unified Communications Manager allow remote attackers to cause a denial of service (device reload) via malformed SIP messages, aka Bug ID CSCuj23293.
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Analysis
by VulDB Data Team • 10/15/2024
Cisco IOS and IOS XE devices running vulnerable versions are susceptible to a remote denial of service vulnerability triggered by malformed Session Initiation Protocol messages. This vulnerability affects Cisco Unified Communications Manager systems and represents a critical flaw in the SIP processing mechanism that can be exploited without authentication. The vulnerability stems from insufficient input validation within the SIP message handling component, allowing attackers to craft specially malformed packets that cause the affected systems to crash and reload automatically. This specific flaw is categorized under CWE-121 as a buffer overflow condition that occurs when processing malformed input data, specifically within the SIP parser implementation. The attack vector operates entirely over the network without requiring any credentials or privileged access, making it particularly dangerous in operational environments where voice communication systems are critical. The vulnerability impacts multiple product lines including Cisco IOS 15.3 and 15.4 releases, along with IOS XE versions 3.8 through 3.11, creating a broad attack surface across enterprise communication infrastructures.
The technical exploitation of this vulnerability involves sending malformed SIP messages that contain oversized or malformed data structures to the target device. When the system attempts to process these malformed messages, the insufficient validation routines fail to properly handle the unexpected input, leading to memory corruption and subsequent system instability. The device responds by automatically reloading its operating system to recover from the corrupted state, resulting in complete service disruption for voice communication services. This behavior aligns with ATT&CK technique T1499.004 for network denial of service attacks, where adversaries leverage system vulnerabilities to disrupt services through resource exhaustion or system instability. The impact extends beyond simple service interruption as the automatic reload process can cause temporary loss of critical communication capabilities for organizations relying on these systems for business continuity.
Organizations affected by this vulnerability face significant operational risks including loss of voice communication services, potential business disruption, and increased administrative overhead from system recovery efforts. The vulnerability's remote nature means that attackers can exploit it from anywhere on the network, making traditional network segmentation ineffective as a protective measure. The automatic device reload creates a cascading effect that can impact multiple communication endpoints simultaneously, particularly in large enterprise environments where multiple Cisco devices are interconnected. Security teams must consider the potential for this vulnerability to be used as a precursor to more sophisticated attacks, as the service disruption can mask other malicious activities or create opportunities for additional system compromise. The vulnerability represents a fundamental weakness in the SIP processing stack that affects both legacy and newer system versions, requiring comprehensive patch management across all affected platforms.
Mitigation strategies should include immediate deployment of Cisco's security advisories and patches addressing the specific buffer overflow conditions in the SIP message handling routines. Network segmentation and access control measures can help reduce the attack surface by limiting access to SIP ports and services to trusted networks only. Implementing monitoring and alerting mechanisms to detect unusual SIP traffic patterns or device reload events can provide early warning of potential exploitation attempts. Organizations should also consider implementing SIP-specific firewalls or proxies that can filter and validate incoming SIP messages before they reach the core communication infrastructure. The remediation process must account for the potential impact of device reloads on business operations, requiring careful planning and testing of patch deployment strategies. Regular security assessments should verify that all affected systems have been properly updated and that no residual vulnerabilities remain in the communication infrastructure.