Source: cve@mitre.org
AIX batch queue (bsh) allows local and remote users to gain additional privileges when network printing is enabled.
AIX systems with network printing enabled are vulnerable to a privilege escalation attack. This allows both local and remote attackers to gain unauthorized access, potentially leading to complete system compromise. The vulnerability stems from flaws in the batch queue (bsh) functionality, enabling attackers to execute arbitrary code with elevated privileges.
Step 1: Network Printing Enabled: The target AIX system must have network printing enabled, allowing it to receive print jobs from remote sources.
Step 2: Malicious Print Job Submission: An attacker crafts a malicious print job, potentially containing specially crafted PostScript or other print-related data. This data includes malicious commands or code designed to exploit the bsh vulnerability.
Step 3: Print Job Processing: The print job is submitted to the AIX system, and the bsh process receives and processes it. The bsh process, due to its elevated privileges, handles the print job.
Step 4: Vulnerability Trigger: The bsh process, while processing the malicious print job, executes the attacker-supplied code or commands. This could be through command injection, format string bugs, or other vulnerabilities in the print job handling logic.
Step 5: Privilege Escalation: The attacker's code executes with the privileges of the bsh process, allowing the attacker to gain elevated privileges, potentially root access.
Step 6: System Compromise: With elevated privileges, the attacker can install backdoors, steal sensitive data, or otherwise compromise the system.
The vulnerability lies within the AIX batch queue (bsh) functionality, specifically when network printing is enabled. The root cause is likely a privilege escalation flaw. The bsh process, when handling print jobs, likely doesn't adequately sanitize or validate user-supplied input related to print job parameters or the print spooler's interaction with the network printing service. This allows an attacker to inject malicious commands or code into the print job, which is then executed with the privileges of the bsh process (often root or a privileged user). The lack of proper input validation, combined with the elevated privileges of the bsh process, creates a pathway for attackers to execute arbitrary code and gain control of the system. The exact nature of the flaw could be a command injection vulnerability, where attacker-controlled input is directly passed to a system command without proper sanitization, or a format string vulnerability if the print job processing uses format string functions on attacker-controlled data.
While specific APT groups are not definitively linked to this specific CVE, the nature of the vulnerability (privilege escalation) makes it attractive to various threat actors. This type of vulnerability is often used by attackers for initial access or lateral movement. CISA KEV status: Not Listed
Monitor network traffic for unusual print job submissions, especially those originating from untrusted sources.
Analyze print job logs for suspicious commands or data. Look for unusual characters or patterns in PostScript or other print job data.
Examine system logs for unexpected processes spawned by the bsh process.
Monitor file system activity for unauthorized modifications, especially in system directories.
Use intrusion detection systems (IDS) and intrusion prevention systems (IPS) with signatures designed to detect known exploits for this vulnerability (if available).
Review the configuration of the print spooler and network printing services for any misconfigurations.
Disable network printing if not required. This is the most effective mitigation if network printing is unnecessary.
Apply security patches and updates from IBM for AIX. Ensure the system is running the latest security updates.
Implement strong input validation and sanitization for all print job parameters and data. This prevents command injection and other vulnerabilities.
Restrict access to the print queue and print spooler services. Limit the users and systems that can submit print jobs.
Monitor system logs and network traffic for suspicious activity related to print jobs.
Implement a least-privilege model for the bsh process. Reduce the privileges of the bsh process to the minimum required for its operation.
Regularly audit system configurations and security settings.