CVE-2022-29527 in amazon-ssm-agent
Summary
by MITRE • 04/20/2022
Amazon AWS amazon-ssm-agent before 3.1.1208.0 creates a world-writable sudoers file, which allows local attackers to inject Sudo rules and escalate privileges to root. This occurs in certain situations involving a race condition.
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Analysis
by VulDB Data Team • 08/03/2023
The vulnerability identified as CVE-2022-29527 affects Amazon Web Services amazon-ssm-agent versions prior to 3.1.1208.0, presenting a critical privilege escalation risk through improper file permissions. This flaw enables local attackers to exploit a race condition scenario that results in the creation of a world-writable sudoers file, fundamentally compromising system security. The issue stems from the agent's failure to properly secure temporary files during its operation, creating an attack surface that adversaries can leverage to gain elevated privileges.
The technical implementation of this vulnerability involves a race condition where the amazon-ssm-agent creates temporary sudoers files with overly permissive permissions. Specifically, when the agent executes certain operations, it generates files that are accessible for writing by all users on the system. This misconfiguration allows attackers to inject malicious sudo rules into the compromised file, effectively bypassing the normal privilege separation mechanisms. The vulnerability manifests when the agent processes commands that require elevated permissions, creating a window where the temporary sudoers file exists with world-writable permissions.
From an operational impact perspective, this vulnerability represents a severe threat to cloud infrastructure security, particularly in environments where the amazon-ssm-agent is deployed across multiple systems. The privilege escalation capability means that attackers who gain access to a low-privilege user account can potentially achieve full root access to the affected systems. This creates a significant risk for organizations relying on AWS infrastructure, as compromised systems can be used as stepping stones for further attacks within the network. The race condition aspect makes this vulnerability particularly challenging to prevent, as it depends on timing and system state during the agent's execution.
The security implications extend beyond immediate privilege escalation, as this vulnerability aligns with attack patterns documented in the MITRE ATT&CK framework under privilege escalation techniques. The flaw demonstrates a classic path to system compromise through insecure temporary file handling, which is categorized as a weakness in the CWE database under CWE-732. Organizations using AWS services must consider this vulnerability as part of their broader security posture, particularly in environments where multiple users or processes interact with the same systems. The vulnerability also highlights the importance of proper file permission management and the need for robust privilege separation mechanisms in automated agent systems.
Mitigation strategies should focus on immediate patching of the amazon-ssm-agent to version 3.1.1208.0 or later, which addresses the race condition and proper file permission handling. System administrators should also implement additional monitoring for unauthorized modifications to sudoers files and conduct regular security audits of agent configurations. Organizations should consider implementing principle of least privilege controls and restricting local user access to systems running the affected agent. The vulnerability serves as a reminder of the critical importance of proper file permission management in security-critical software components, particularly in cloud environments where automated agents operate with elevated privileges.