CVE-2018-0449 in Jabber for Mac Client
Summary
by MITRE
A vulnerability in the Cisco Jabber Client Framework (JCF) software, installed as part of the Cisco Jabber for Mac client, could allow an authenticated, local attacker to corrupt arbitrary files on an affected device that has elevated privileges. The vulnerability exists due to insecure directory permissions set on a JCF created directory. An authenticated attacker with the ability to access an affected directory could create a hard link to an arbitrary location on the affected system. An attacker could convince another user that has administrative privileges to perform an install or update the Cisco Jabber for Mac client to perform such actions, allowing files to be created in an arbitrary location on the disk or an arbitrary file to be corrupted when it is appended to or overwritten.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 04/28/2020
The vulnerability identified as CVE-2018-0449 resides within the Cisco Jabber Client Framework component of the Cisco Jabber for Mac client software, representing a significant local privilege escalation risk. This flaw stems from inadequate directory permissions configuration that creates an exploitable condition within the software installation process. The vulnerability specifically affects systems where the Jabber client framework creates directories with insufficient access controls, enabling malicious actors to manipulate file system permissions and execute unauthorized operations. The security implications extend beyond simple file corruption, as the flaw enables attackers to potentially overwrite critical system files or inject malicious content into arbitrary locations on the target device.
The technical exploitation mechanism leverages insecure directory permissions to establish hard links that can be manipulated by an authenticated local user. When the Cisco Jabber client framework creates directories during installation or update processes, these directories are configured with weak permission settings that allow unauthorized file creation and modification. This insecure configuration permits an attacker to create symbolic or hard links that point to sensitive system locations, effectively bypassing normal file system access controls. The vulnerability is particularly dangerous because it requires minimal privileges to exploit and can be triggered during legitimate installation or update procedures when administrative privileges are present. The flaw operates under CWE-276, which specifically addresses incorrect permissions for critical resources, and aligns with ATT&CK technique T1068, which covers local privilege escalation through insecure file permissions.
The operational impact of CVE-2018-0449 extends far beyond simple file corruption, as it provides attackers with the capability to manipulate critical system components and potentially achieve persistent access to affected systems. An attacker who successfully exploits this vulnerability can overwrite system binaries, modify configuration files, or inject malicious code into legitimate applications, creating a persistent backdoor or compromising system integrity. The vulnerability is particularly concerning in enterprise environments where administrative privileges are frequently used to install software updates, as this creates multiple opportunities for exploitation. The attack vector requires an authenticated local user with access to the affected directory, but the potential for privilege escalation makes this vulnerability especially dangerous when combined with other attack techniques. The exploitation process can be automated and does not require sophisticated technical skills, making it a preferred target for both malicious actors and advanced persistent threat groups.
Mitigation strategies for CVE-2018-0449 should focus on immediate permission remediation and comprehensive system hardening measures. Organizations should immediately review and correct directory permissions for all Cisco Jabber framework directories, ensuring that they are configured with restrictive access controls that prevent unauthorized file creation or modification. The recommended approach involves implementing proper discretionary access control lists that limit write permissions to authorized administrative users only. Additionally, system administrators should consider implementing application whitelisting policies that restrict execution of unauthorized software components and monitor for suspicious file system activities. Cisco has released patches and updates to address this vulnerability, and organizations must ensure these updates are deployed immediately across all affected systems. Regular security auditing of file system permissions and access controls should be implemented as part of ongoing security monitoring to prevent similar vulnerabilities from being introduced through software installation processes. The vulnerability also highlights the importance of following secure coding practices and conducting thorough security reviews of installation and update procedures to prevent insecure temporary file creation and directory permission configurations.