CVE-2015-5699 in Linux
Summary
by MITRE
The Switch Configuration Tools Backend (clcmd_server) in Cumulus Linux 2.5.3 and earlier allows local users to execute arbitrary commands via shell metacharacters in a cl-rctl command label.
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Analysis
by VulDB Data Team • 11/28/2019
The vulnerability identified as CVE-2015-5699 resides within the Switch Configuration Tools Backend component known as clcmd_server in Cumulus Linux versions 2.5.3 and earlier. This represents a critical security flaw that enables local attackers to escalate privileges and execute arbitrary code on affected systems. The vulnerability stems from inadequate input validation within the cl-rctl command processing functionality, where shell metacharacters are not properly sanitized or escaped before being processed by the backend system. This allows malicious actors with local access to manipulate command execution flows through carefully crafted input parameters that contain shell special characters such as semicolons, pipes, or command substitution operators. The affected clcmd_server component serves as a critical backend service responsible for handling configuration commands and system management operations within the Cumulus Linux environment, making this vulnerability particularly dangerous as it provides a direct pathway for privilege escalation and system compromise. The vulnerability aligns with CWE-78, which specifically addresses Improper Neutralization of Special Elements used in an OS Command, and represents a classic command injection flaw that has been consistently exploited across various network operating systems and embedded devices.
The operational impact of CVE-2015-5699 extends beyond simple command execution capabilities to encompass full system compromise and potential lateral movement within network infrastructure. Local users who can interact with the cl-rctl command interface gain the ability to execute arbitrary system commands with the privileges of the clcmd_server process, which typically runs with elevated permissions to manage network switch configurations. This vulnerability can be exploited to install backdoors, modify system files, disable security mechanisms, or exfiltrate sensitive configuration data from network switches running affected Cumulus Linux versions. The attack surface is particularly concerning in enterprise network environments where switches serve as critical infrastructure components and where local access might be obtained through various means including physical access, compromised user accounts, or other initial compromise vectors. From an operational security perspective, this vulnerability undermines the integrity of network device management and configuration processes, potentially allowing attackers to modify network policies, redirect traffic, or establish persistent access points within the network infrastructure. The vulnerability also aligns with ATT&CK technique T1059.001 for Command and Scripting Interpreter, specifically focusing on the execution of system commands through shell interfaces, and represents a common attack pattern in network security exploitation.
Mitigation strategies for CVE-2015-5699 should prioritize immediate patching of affected Cumulus Linux installations to version 2.5.4 or later, which contains the necessary fixes to properly sanitize input parameters and prevent shell metacharacter injection. Organizations should implement comprehensive input validation measures at all levels of the application stack, ensuring that all user-supplied data passed to system commands undergoes proper sanitization and escaping before processing. Network administrators should conduct thorough inventory assessments to identify all affected devices running vulnerable Cumulus Linux versions and prioritize remediation efforts based on risk exposure and criticality of the affected switches. Additional defensive measures include implementing least privilege access controls for local user accounts, monitoring system logs for suspicious command execution patterns, and establishing network segmentation to limit the potential impact of successful exploitation. The vulnerability demonstrates the importance of proper secure coding practices and input validation in network infrastructure software, emphasizing the need for regular security assessments and vulnerability management programs. Organizations should also consider implementing intrusion detection systems capable of identifying command injection attempts and establishing automated patch management processes to ensure timely remediation of similar vulnerabilities across their network infrastructure. Regular security training for system administrators and network engineers regarding secure coding practices and common attack patterns helps reduce the likelihood of exploitation through human error or oversight.