Source: cve@mitre.org
Buffer overflow in xlock in UnixWare 7.1.0 and 7.1.1 and Open Unix 8.0.0 allows local users to execute arbitrary code.
CVE-2001-1478 presents a critical buffer overflow vulnerability in the xlock utility on older UnixWare and Open Unix systems, allowing local users to gain arbitrary code execution. Successful exploitation grants attackers elevated privileges, potentially leading to complete system compromise and data exfiltration.
Step 1: User Interaction: A local user, or an attacker with local access, interacts with the xlock program. This interaction can be through command-line arguments or potentially through configuration files.
Step 2: Input Delivery: The attacker provides a specially crafted input string, designed to exceed the allocated buffer size within xlock.
Step 3: Buffer Overflow: The xlock program processes the malicious input, and due to the lack of bounds checking, the input overflows the designated buffer.
Step 4: Memory Corruption: The overflow overwrites adjacent memory regions, including the return address on the stack.
Step 5: Shellcode Injection (Optional): The attacker may include shellcode within the overflowing input, or the overflow may be used to point the return address to existing code within the program or a shared library.
Step 6: Code Execution: When xlock attempts to return from the vulnerable function, the overwritten return address directs execution to the attacker's shellcode (or a controlled location), granting the attacker control over the system with the privileges of the user running xlock.
The vulnerability stems from a buffer overflow in the xlock program. Specifically, the program fails to properly validate the size of user-supplied input, leading to a write beyond the allocated memory buffer. This allows an attacker to overwrite adjacent memory regions, including critical program data such as the return address. By carefully crafting the input, an attacker can overwrite the return address with the address of malicious code (shellcode) injected into the buffer, leading to arbitrary code execution with the privileges of the user running xlock. The root cause is a lack of bounds checking on input parameters used by xlock when processing user-supplied data, likely related to how command-line arguments or configuration files are handled. This allows for a classic stack-based buffer overflow scenario.
While no specific APT groups are definitively linked to this specific CVE, the nature of the vulnerability makes it attractive to various threat actors seeking to gain initial access or escalate privileges. Given the age of the vulnerability, it is unlikely to be a primary target for sophisticated attacks, but it could be used in conjunction with other exploits. CISA KEV status: Not Listed.
Monitor system logs for unusual activity related to xlock, such as unexpected crashes or errors.
Analyze process execution logs for suspicious command-line arguments passed to xlock.
Examine core dumps generated by xlock for evidence of memory corruption.
Network traffic analysis may not be directly relevant, as this is a local privilege escalation vulnerability.
File integrity monitoring to detect changes to the xlock executable or related libraries.
Patching: Apply the security patches provided by the vendor (if available) for the affected operating systems. This is the most effective solution.
Upgrade: Upgrade to a supported and patched version of the operating system. This is the preferred long-term solution.
Remove/Disable: If xlock is not essential for system operation, remove or disable it to eliminate the attack surface.
Least Privilege: Ensure that users do not have unnecessary privileges. Limit the permissions of users who interact with the system.
Intrusion Detection/Prevention Systems (IDS/IPS): Deploy IDS/IPS solutions to detect and potentially block exploitation attempts, although this is less effective for local privilege escalation.
Regular Security Audits: Conduct regular security audits and vulnerability scans to identify and address potential weaknesses.