CVE-2015-5189 in PCS
Summary
by MITRE
Race condition in pcsd in PCS 0.9.139 and earlier uses a global variable to validate usernames, which allows remote authenticated users to gain privileges by sending a command that is checked for security after another user is authenticated.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 06/14/2022
The vulnerability identified as CVE-2015-5189 represents a critical race condition flaw within the pcsd component of the Pacemaker Cluster Suite version 0.9.139 and earlier. This issue stems from the improper handling of global variables during the username validation process, creating a window of opportunity for malicious actors to exploit the system's security mechanisms. The vulnerability specifically affects remote authenticated users who can manipulate the authentication flow to escalate their privileges within the cluster environment.
The technical root cause of this vulnerability lies in the use of a global variable for username validation within the pcsd service. When multiple users authenticate simultaneously, the global variable that stores the current authentication state becomes susceptible to race conditions. During the command execution process, the system checks user permissions after another user has already been authenticated, allowing an attacker to manipulate the validation context. This flaw operates under the principle of concurrent access to shared resources without proper synchronization mechanisms, making it particularly dangerous in multi-user cluster environments where multiple authentication sessions may occur simultaneously.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it fundamentally undermines the integrity of the authentication system within Pacemaker clusters. An authenticated attacker can leverage this race condition to execute commands with elevated privileges that should only be available to authorized administrators. This creates a significant risk for cluster environments where multiple users may have legitimate access but where the system's security model relies on proper isolation between authentication contexts. The vulnerability affects the core security model of the cluster management system, potentially allowing attackers to gain unauthorized access to cluster resources, modify configurations, or disrupt service availability.
From a cybersecurity perspective, this vulnerability aligns with CWE-362, which specifically addresses race conditions in concurrent programming environments. The flaw also relates to ATT&CK technique T1078 which covers valid accounts and privilege escalation through legitimate system access. The vulnerability demonstrates how improper synchronization in shared memory contexts can lead to serious security implications, particularly in enterprise cluster management systems where maintaining proper access controls is critical. Organizations using affected versions of Pacemaker should consider this vulnerability as a high-priority threat that could enable attackers to compromise entire cluster infrastructures. The recommended mitigation involves upgrading to versions of PCS that address the race condition through proper synchronization mechanisms and implementation of thread-safe authentication validation processes, ensuring that global variables used in security contexts are properly protected against concurrent access violations.