CVE-2017-15566 in Slurm
Summary
by MITRE
Insecure SPANK environment variable handling exists in SchedMD Slurm before 16.05.11, 17.x before 17.02.9, and 17.11.x before 17.11.0rc2, allowing privilege escalation to root during Prolog or Epilog execution.
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Analysis
by VulDB Data Team • 01/21/2021
The vulnerability identified as CVE-2017-15566 represents a critical privilege escalation flaw in the SchedMD Slurm workload management system that affects multiple version ranges including 16.05.11, 17.02.9, and 17.11.0rc2. This issue stems from insecure handling of the SPANK environment variable during Prolog and Epilog script execution phases, creating a significant security risk for high-performance computing environments that rely on Slurm for job scheduling and resource management.
The technical flaw manifests when Slurm processes Prolog and Epilog scripts that are executed with elevated privileges during job lifecycle events. The SPANK environment variable mechanism fails to properly sanitize or validate input parameters, allowing malicious actors to inject arbitrary environment variables that can be exploited during script execution. This vulnerability specifically affects the privilege escalation process because Slurm's handling of these environment variables does not adequately enforce security boundaries, particularly when transitioning from user contexts to root privileges during job execution phases.
The operational impact of this vulnerability is severe within HPC environments where Slurm serves as the central job scheduler and resource manager. Attackers who can manipulate the SPANK environment variable during Prolog or Epilog execution can gain root privileges on the system, potentially allowing them to execute arbitrary code, modify critical system files, or compromise the entire computing cluster. This privilege escalation capability undermines the fundamental security model of HPC systems where job scheduling and resource management require careful privilege separation to prevent unauthorized access to system resources.
The vulnerability aligns with CWE-276, which describes improper privileges, and demonstrates characteristics consistent with privilege escalation attacks in Unix-like systems. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques where adversaries leverage insecure configuration or handling of system components to gain elevated privileges. The attack vector specifically involves manipulating environment variables during job execution phases, which falls under the technique of environment variable manipulation for privilege escalation.
Mitigation strategies for CVE-2017-15566 require immediate patching of affected Slurm versions to the recommended secure releases including 16.05.11, 17.02.9, and 17.11.0rc2. System administrators should also implement strict environment variable validation policies for Prolog and Epilog scripts, disable unnecessary SPANK functionality when not required, and conduct thorough security reviews of all job execution scripts. Additionally, monitoring for unauthorized changes to Slurm configuration files and environment variable handling should be implemented as part of comprehensive security operations to detect potential exploitation attempts. Organizations should also consider implementing principle of least privilege for Slurm configuration and ensure proper access controls are in place for system administration functions.