Source: cve@mitre.org
dpsexec (DPS Server) when running under XDM in IBM AIX 3.2.5 and earlier does not properly check privileges, which allows local users to overwrite arbitrary files and gain privileges.
IBM AIX systems running vulnerable versions are susceptible to a critical privilege escalation vulnerability. Exploiting the dpsexec service allows local attackers to overwrite arbitrary files, potentially leading to complete system compromise and unauthorized access. This vulnerability, dating back to 1994, highlights the importance of patching legacy systems and maintaining strong access controls.
Step 1: Identify Vulnerable System: The attacker identifies an IBM AIX system running a vulnerable version (3.2.5 or earlier).
Step 2: Local Access: The attacker gains local access to the system, potentially through a compromised account or physical access.
Step 3: Exploit Execution: The attacker crafts a malicious payload designed to overwrite a critical system file, such as /etc/passwd or a setuid binary like su.
Step 4: dpsexec Interaction: The attacker leverages the dpsexec service, exploiting the lack of privilege checks.
Step 5: File Overwrite: The attacker uses dpsexec to overwrite the targeted system file with their malicious payload.
Step 6: Privilege Escalation: The attacker triggers the execution of the overwritten file (e.g., by attempting to su or logging in), gaining root privileges.
The vulnerability stems from a flaw in the dpsexec service, specifically within its privilege checking mechanisms when running under XDM. The service fails to adequately validate the privileges of the user attempting to execute commands, allowing a local user to overwrite files owned by other users, including critical system files. This lack of proper authorization control allows an attacker to replace system binaries, such as su or login, with malicious versions, effectively gaining root access. The root cause is a missing or inadequate check on the user's permissions before allowing file operations, leading to a privilege escalation scenario. The vulnerability is exacerbated by the service's privileged context under XDM, which provides a direct path to elevated privileges once a file overwrite is achieved.
While no specific APT groups are directly linked to exploiting this specific CVE, the nature of the vulnerability (privilege escalation) makes it attractive to any threat actor seeking to compromise a system. The impact of such a vulnerability could be leveraged by various threat actors, including those seeking to establish persistence, steal data, or disrupt operations. This CVE is not listed in the CISA KEV.
Monitor system logs for suspicious activity related to dpsexec and file modifications, especially those affecting system binaries or configuration files.
Analyze file integrity using tools like tripwire or aide to detect unauthorized changes to critical system files.
Review user login attempts and privilege escalation attempts, looking for unusual patterns or anomalies.
Network traffic analysis: While this is a local vulnerability, any remote access attempts to the system should be scrutinized, as they could indicate a compromised system attempting to exploit the vulnerability.
Upgrade to a patched version of IBM AIX (3.2.5 or later, with applicable security patches).
Implement strong access controls and least privilege principles to limit the impact of a potential compromise.
Regularly audit system configurations and user accounts to identify and address security vulnerabilities.
Monitor system logs for suspicious activity and file modifications.
Consider disabling the dpsexec service if it is not required for system functionality. If disabled, ensure that the system's functionality is not impacted.