CVE-2017-13130 in Patrol
Summary
by MITRE
mcmnm in BMC Patrol allows local users to gain privileges via a crafted libmcmclnx.so file in the current working directory, because it is setuid root and the RPATH variable begins with the .: substring.
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Analysis
by VulDB Data Team • 11/09/2019
The vulnerability identified as CVE-2017-13130 affects the mcmnm component within BMC Patrol, a widely used systems management and monitoring solution. This issue represents a classic privilege escalation flaw that exploits the insecure handling of shared library loading mechanisms. The vulnerability specifically targets the libmcmclnx.so library file which is part of the mcmnm process that runs with root privileges due to its setuid bit being enabled. The core technical flaw stems from the improper configuration of the RPATH variable in the mcmnm executable, which includes the current directory prefix .: at the beginning of the library search path. This configuration creates a dangerous condition where any malicious actor can place a specially crafted libmcmclnx.so file in the current working directory and influence the execution flow of the privileged process.
The operational impact of this vulnerability is significant as it allows local users to escalate their privileges from regular user level to root access without requiring authentication or specialized tools. The attack vector is relatively straightforward since an attacker only needs to have write access to the current working directory where mcmnm is executed. This scenario commonly occurs in environments where users can execute applications from directories with shared write permissions or when applications are launched from user-controlled locations. The vulnerability aligns with CWE-426 Untrusted Search Path, which specifically addresses the risk of executables loading libraries from insecure locations, and also relates to CWE-276 Incorrect Permissions, as the setuid root binary should not be vulnerable to path manipulation attacks.
From an attack perspective, this vulnerability demonstrates how improper library loading practices can undermine even the most secure system designs. The RPATH configuration creates a predictable and exploitable condition where the system will first search the current directory before checking standard system library locations. This behavior violates fundamental security principles outlined in the MITRE ATT&CK framework under the Privilege Escalation tactic, specifically targeting the technique of Exploitation for Privilege Escalation. The vulnerability affects organizations running BMC Patrol versions that include the vulnerable mcmnm component, making it particularly concerning for enterprise environments where system monitoring tools often run with elevated privileges. The attack requires minimal resources and can be executed by any local user who has the ability to write files in the directory from which mcmnm is executed.
Mitigation strategies for this vulnerability should focus on immediate remediation of the library loading configuration. Organizations should ensure that the RPATH variable for the mcmnm binary does not include the current directory prefix .: in its search path, and instead should explicitly define secure library locations. The recommended approach involves either removing the .: prefix from RPATH or using absolute paths for all required libraries. Additionally, system administrators should verify that the setuid bit is properly configured and consider implementing additional security controls such as file system permissions, capability-based restrictions, or mandatory access controls. Regular auditing of setuid binaries and their library dependencies should be conducted to identify similar vulnerabilities across the system. The vulnerability also highlights the importance of following secure coding practices and adhering to the principle of least privilege, ensuring that applications run with the minimum necessary permissions. Organizations should also consider implementing file integrity monitoring solutions to detect unauthorized modifications to critical system binaries and their associated library files.