CVE-2009-5007 in AnyConnect SSL VPN
Summary
by MITRE
The Cisco trial client on Linux for Cisco AnyConnect SSL VPN allows local users to overwrite arbitrary files via a symlink attack on unspecified temporary files.
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Analysis
by VulDB Data Team • 03/17/2017
The vulnerability identified as CVE-2009-5007 resides within the Cisco trial client implementation for Linux operating systems that interfaces with Cisco AnyConnect SSL VPN services. This security flaw represents a critical path traversal and privilege escalation vector that enables local attackers to manipulate the system's file structure through malicious symbolic link manipulation. The vulnerability specifically affects the trial client version of Cisco AnyConnect, which is designed to provide temporary access to VPN services for evaluation purposes, making it particularly concerning for organizations that may deploy these trial versions in production environments.
The technical implementation of this vulnerability stems from improper handling of temporary files during the client execution process on Linux systems. When the Cisco AnyConnect trial client operates, it creates temporary files in predictable locations that can be manipulated by local users through symbolic link attacks. This flaw allows attackers to create malicious symbolic links that point to sensitive system files or directories, enabling them to overwrite arbitrary files with unauthorized content. The vulnerability manifests when the client processes these temporary files without proper validation of their symbolic link status or without implementing secure temporary file creation mechanisms. This behavior directly aligns with CWE-377, which addresses insecure temporary file handling practices, and CWE-378, which covers the creation of temporary files with insecure permissions.
The operational impact of CVE-2009-5007 extends beyond simple file overwriting capabilities, as it provides attackers with a potential pathway for privilege escalation and persistent system compromise. Local users who can execute the trial client can leverage this vulnerability to overwrite critical system files, configuration files, or even binaries that the client may access during its operation. This capability could enable attackers to establish backdoors, modify system configurations, or gain elevated privileges within the compromised system. The vulnerability's exploitation requires local access to the system, but given that many users may have such access, particularly in enterprise environments where trial software might be installed by various personnel, the attack surface remains substantial. The attack pattern for this vulnerability closely follows ATT&CK technique T1059.007, which involves the use of script-based commands, and T1068, which addresses local privilege escalation through improper file permissions.
Mitigation strategies for CVE-2009-5007 should focus on both immediate remediation and long-term architectural improvements. Organizations should immediately disable or remove the Cisco AnyConnect trial client from systems where it is not absolutely required, particularly in production environments. When the trial client must remain installed, administrators should implement strict file system permissions and ensure that temporary file creation follows secure practices such as creating files with unique names and appropriate permissions before making them accessible. The system should also implement proper file system monitoring to detect unauthorized symbolic link creation in temporary directories. Additionally, organizations should consider implementing privilege separation mechanisms where the trial client runs with minimal necessary privileges and does not have write access to critical system directories. Regular security assessments should include verification that temporary file handling practices meet industry standards such as those outlined in the OWASP Secure Coding Practices and NIST Special Publication 800-128, which provide comprehensive guidance on secure temporary file creation and management to prevent exactly this type of vulnerability exploitation.