CVE-2013-3403 in Unified Communications Manager
Summary
by MITRE
Multiple untrusted search path vulnerabilities in Cisco Unified Communications Manager (CUCM) 7.1(x) through 9.1(1a) allow local users to gain privileges by leveraging unspecified file-permission and environment-variable issues for privileged programs, aka Bug ID CSCuh73454.
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Analysis
by VulDB Data Team • 05/06/2017
Cisco Unified Communications Manager versions 7.1 through 9.1(1a) contain multiple untrusted search path vulnerabilities that enable local attackers to escalate privileges through unspecified file permission and environment variable issues affecting privileged programs. These vulnerabilities fall under the CWE-426 Untrusted Search Path category, where applications search for required libraries or executables in directories that can be manipulated by attackers. The specific Bug ID CSCuh73454 indicates that the flaw involves the improper handling of environment variables during program execution, allowing malicious actors to insert arbitrary code into the search path. The vulnerability occurs when privileged programs in CUCM do not properly validate or sanitize the paths used to locate required components, creating opportunities for attackers to place malicious binaries or libraries in directories that are searched before legitimate system directories. This issue represents a classic privilege escalation vector that aligns with ATT&CK technique T1068 Privilege Escalation through the exploitation of environment variable manipulation and path traversal vulnerabilities. Attackers can exploit these weaknesses by placing malicious executables in directories that are searched first, potentially allowing them to execute code with elevated privileges. The impact extends beyond simple privilege escalation as it affects the integrity and confidentiality of the entire communications platform, potentially enabling attackers to intercept communications, modify call routing, or gain unauthorized access to sensitive telephony data. The vulnerability is particularly concerning because it affects multiple versions of CUCM, making it a widespread issue across different deployment scenarios.
The technical implementation of this vulnerability stems from the insecure handling of library loading mechanisms within the CUCM environment. When privileged processes execute, they typically use a predefined search path to locate required shared libraries or executables. The flaw occurs when these search paths include directories that are writable by unprivileged users or when environment variables are not properly sanitized before program execution. This creates an opportunity for attackers to manipulate the execution flow by placing malicious code in directories that are searched before the legitimate system directories. The vulnerability is classified under CWE-426 which specifically addresses situations where applications search for files in untrusted locations, often through environment variables such as PATH, LD_LIBRARY_PATH, or similar mechanisms. This type of vulnerability is particularly dangerous because it can be exploited without requiring network access or external authentication, making it a significant concern for on-premise deployments where physical access might be possible. The exploitation process typically involves placing a malicious library or executable in a directory that is searched before the legitimate system directories, then triggering the execution of the privileged program to load and execute the attacker-controlled code. This attack pattern is consistent with ATT&CK technique T1068 and represents a fundamental flaw in the privilege separation mechanisms within the CUCM platform.
The operational impact of CVE-2013-3403 extends far beyond simple privilege escalation, as it fundamentally compromises the security posture of Cisco Unified Communications Manager installations. Successful exploitation allows attackers to gain elevated privileges within the telephony infrastructure, potentially enabling them to manipulate call routing, intercept voice communications, modify user accounts, or even disable critical telephony services. The vulnerability affects the core integrity of the communications platform, making it possible for attackers to establish persistent access points within the network. Organizations using affected CUCM versions face significant risk of data breaches, service disruption, and potential compliance violations, particularly in regulated environments where telephony security is critical. The attack vector is particularly concerning because it can be exploited locally, meaning that any individual with access to the system can potentially escalate their privileges, regardless of their initial authentication level. This makes the vulnerability especially dangerous in environments where multiple users have access to the system, as it could enable lateral movement within the network or provide a foothold for more sophisticated attacks. The widespread nature of the affected versions means that many organizations across various industries, including healthcare, financial services, and government sectors, could be at risk. The vulnerability also represents a significant challenge for incident response teams, as it requires careful forensic analysis to determine whether the system has been compromised and what specific privileges may have been gained by an attacker.
Mitigation strategies for CVE-2013-3403 should focus on both immediate remediation and long-term security hardening measures. The most effective immediate solution involves applying the relevant Cisco security patches and updates that address the specific search path vulnerabilities in affected CUCM versions. Organizations should also implement strict environment variable controls, ensuring that privileged programs do not search in directories that are writable by unprivileged users. This includes validating and sanitizing PATH and LD_LIBRARY_PATH variables before program execution, and ensuring that system directories are prioritized in the search path. Network segmentation and access controls should be implemented to limit physical access to CUCM systems, as the vulnerability can be exploited locally. Regular security audits should be conducted to verify that environment variables are properly configured and that no unauthorized modifications have been made to system directories. Additionally, implementing monitoring solutions that can detect unusual file creation patterns in system directories or unexpected privilege escalation events can help identify potential exploitation attempts. Organizations should also consider implementing the principle of least privilege, ensuring that only necessary users have access to the system and that all access is properly logged and monitored. The vulnerability highlights the importance of secure coding practices and proper privilege separation mechanisms, making it essential for organizations to review their security configurations and ensure that all system components follow secure implementation guidelines. Regular vulnerability assessments and penetration testing should be conducted to identify similar issues in other parts of the network infrastructure, as this type of vulnerability often indicates broader security weaknesses in the system architecture.