CVE-2017-2616 in util-linux
Summary
by MITRE
A race condition was found in util-linux before 2.32.1 in the way su handled the management of child processes. A local authenticated attacker could use this flaw to kill other processes with root privileges under specific conditions.
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Analysis
by VulDB Data Team • 12/02/2022
The vulnerability identified as CVE-2017-2616 represents a critical race condition within the util-linux package version 2.32.1 and earlier, specifically affecting the su command's handling of child process management. This flaw exists in the manner by which the su utility manages the execution context when switching user privileges, creating a window where malicious actions can be exploited to manipulate process lifecycles. The race condition occurs during the transition period when the su command is executing and managing the child process that represents the target user session, particularly when the parent process is in the process of spawning or managing the child execution environment.
The technical implementation of this vulnerability stems from improper synchronization mechanisms within the su command's source code, where the timing of process creation and destruction creates opportunities for exploitation. When an authenticated local user executes the su command with root privileges, the system enters a vulnerable state where process management operations can be manipulated through specific timing conditions. The flaw allows an attacker to craft sequences that cause the su utility to terminate other processes running with root privileges, effectively enabling privilege escalation through process manipulation rather than traditional authentication bypass techniques. This vulnerability specifically affects systems where the su command is used for privilege escalation and where multiple processes might be running concurrently under elevated privileges.
The operational impact of CVE-2017-2616 extends beyond simple privilege escalation capabilities to potentially enable more sophisticated attack vectors within compromised systems. An attacker exploiting this race condition could target running services or critical system processes that operate with root privileges, effectively disrupting system operations or creating backdoor access points. The vulnerability's exploitation requires local authentication and specific conditions related to process timing, but once successful, it provides attackers with the ability to terminate processes that are crucial to system integrity. This capability aligns with attack patterns documented in the mitre ATT&CK framework under privilege escalation techniques, specifically targeting process injection and privilege manipulation methods. The vulnerability also relates to CWE-362, which describes race conditions in concurrent programming, where the timing of operations creates exploitable conditions.
Mitigation strategies for CVE-2017-2616 primarily focus on updating the util-linux package to version 2.32.1 or later, where the race condition has been addressed through proper process management synchronization. System administrators should prioritize patching affected systems, particularly those where the su command is actively used for privilege escalation. Additional defensive measures include implementing proper process monitoring to detect unusual process termination patterns and configuring system access controls to limit local user privileges where possible. Security teams should also consider implementing logging controls that track su command usage and process management activities to detect potential exploitation attempts. The vulnerability demonstrates the importance of proper concurrent programming practices and synchronization mechanisms in system utilities, particularly those handling privilege transitions, and highlights the need for regular security assessments of core system components. Organizations should also review their privilege escalation policies and ensure that alternative methods such as sudo are properly configured to reduce reliance on potentially vulnerable su implementations.