CVE-2007-5538 in Unified Communications Manager
Summary
by MITRE
Buffer overflow in the Centralized TFTP File Locator Service in Cisco Unified Communications Manager (CUCM, formerly CallManager) 5.1 before 5.1(3), and Unified CallManager 5.0, allows remote attackers to execute arbitrary code or cause a denial of service via unspecified vectors involving the processing of filenames, aka CSCsh47712.
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Analysis
by VulDB Data Team • 07/28/2019
The vulnerability identified as CVE-2007-5538 represents a critical buffer overflow flaw within Cisco Unified Communications Manager's Centralized TFTP File Locator Service. This vulnerability affects versions 5.1 before 5.1(3) and Unified CallManager 5.0, exposing organizations to significant security risks. The flaw specifically manifests during the processing of filenames within the TFTP service, creating an exploitable condition that can be leveraged by remote attackers to gain unauthorized system access or disrupt service availability.
The technical nature of this vulnerability stems from improper input validation within the TFTP file locator service implementation. When processing filenames, the system fails to adequately check buffer boundaries, allowing maliciously crafted input to overwrite adjacent memory locations. This buffer overflow condition creates opportunities for attackers to inject and execute arbitrary code with the privileges of the affected service. The vulnerability operates at the application layer and can be exploited remotely without requiring authentication, making it particularly dangerous in networked environments where TFTP services are accessible to untrusted parties.
The operational impact of this vulnerability extends beyond simple code execution capabilities to include potential system compromise and denial of service conditions. Attackers exploiting this flaw could gain complete control over the affected Cisco Unified Communications Manager system, potentially leading to unauthorized access to voice communications, modification of call routing configurations, or complete service disruption. The denial of service aspect means that even unsuccessful exploitation attempts could render the communication system unavailable, impacting business operations and emergency services that rely on these platforms. Organizations utilizing these older versions of Cisco Unified Communications Manager face substantial risk exposure, particularly in environments where network segmentation is inadequate or where the TFTP service is exposed to external networks.
Mitigation strategies for CVE-2007-5538 primarily focus on immediate software updates and network security controls. Cisco has released patches and software updates addressing this vulnerability in version 5.1(3) and subsequent releases, making patch management the primary defense mechanism. Organizations should prioritize upgrading to patched versions of Cisco Unified Communications Manager, as this addresses the root cause of the buffer overflow condition. Network segmentation practices should be implemented to isolate TFTP services from untrusted networks, limiting the attack surface available to potential adversaries. Additional controls including firewall rules to restrict TFTP port access, intrusion detection system monitoring for suspicious TFTP activity, and regular security assessments can provide layered protection against exploitation attempts. The vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and represents a technique that could be mapped to ATT&CK tactics including privilege escalation and execution through remote services. Organizations should also consider implementing network monitoring to detect anomalous filename processing patterns that might indicate exploitation attempts against this vulnerability.