Source: cve@mitre.org
Vulnerability in /bin/mail in SunOS 4.1.1 and earlier allows local users to gain root privileges via certain command line arguments.
SunOS 4.1.1 and earlier systems are vulnerable to a critical local privilege escalation via a flaw in the /bin/mail utility. This vulnerability allows attackers to gain root access by exploiting command-line argument handling. Successful exploitation grants complete control over the compromised system, leading to severe data breaches and system compromise.
Step 1: Craft Malicious Input: The attacker crafts a malicious command-line argument to the /bin/mail program. This argument is designed to exploit the vulnerability.
Step 2: Input Processing: The /bin/mail program processes the malicious command-line argument. Due to the vulnerability, the program fails to properly validate or sanitize the input.
Step 3: Memory Corruption: The crafted input overwrites a critical memory location, such as the return address on the stack. This is often a buffer overflow.
Step 4: Control Hijack: When the program attempts to return from a function, it jumps to the attacker-controlled address.
Step 5: Code Execution: The attacker's code, now running with the privileges of the /bin/mail program (typically the user running the program), executes.
Step 6: Privilege Escalation: The attacker's code is designed to escalate privileges, such as by setting the effective user ID to root, granting the attacker root access.
The vulnerability stems from insufficient input validation and improper handling of command-line arguments within the /bin/mail program. Specifically, the program fails to properly sanitize or validate user-supplied input passed through command-line arguments. This allows an attacker to craft malicious arguments that overwrite critical memory locations, such as the stack or heap, potentially leading to arbitrary code execution. The root cause is a buffer overflow or similar memory corruption vulnerability triggered by malformed input. The lack of proper bounds checking on input buffers allows the attacker to overwrite adjacent memory regions, including return addresses, function pointers, or other sensitive data. This can be exploited to redirect program execution to attacker-controlled code, ultimately leading to root privilege escalation.
While no specific APTs are directly linked to solely exploiting this vulnerability due to its age, it is a common component of older exploit chains. It's likely used in conjunction with other vulnerabilities. Not on CISA KEV.
Monitor system logs for suspicious activity related to /bin/mail, especially unusual command-line arguments.
Analyze process execution logs for instances of /bin/mail being executed with unusual or lengthy command-line arguments.
Inspect core dumps or crash reports for evidence of memory corruption within /bin/mail.
Network traffic analysis: While this is a local exploit, unusual network activity originating from the compromised host after exploitation should be investigated.
Upgrade to a patched version of SunOS or a more modern operating system. This is the primary and most effective remediation.
If upgrading is not immediately possible, restrict access to the /bin/mail program. This can be achieved by limiting the users who can execute the program.
Implement file integrity monitoring to detect any unauthorized modifications to /bin/mail or related system files.
Apply least privilege principles to user accounts to limit the impact of a successful exploit.
Regularly scan the system for known vulnerabilities using vulnerability scanners.