CVE-2007-4621 in AIX
Summary
by MITRE
Buffer overflow in crontab in IBM AIX 5.2 allows local users to gain privileges via long command line arguments.
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Analysis
by VulDB Data Team • 08/23/2019
The vulnerability identified as CVE-2007-4621 represents a critical buffer overflow flaw within the crontab utility of IBM AIX 5.2 operating system. This issue specifically affects the command line argument processing mechanism within the crontab binary, where insufficient input validation allows maliciously crafted long arguments to overwrite adjacent memory locations. The flaw exists in the way the system handles command line parameters passed to the crontab utility, creating an exploitable condition that can be leveraged by local attackers to execute arbitrary code with elevated privileges. The buffer overflow occurs during the parsing of command line arguments, where the system fails to properly bounds-check the input data before copying it into fixed-size memory buffers. This vulnerability is particularly concerning because crontab is a system utility that typically runs with elevated privileges, making successful exploitation directly translate into privilege escalation capabilities for local attackers.
The technical implementation of this buffer overflow stems from improper memory management within the crontab utility's argument parsing code. When users invoke crontab with command line arguments, the system allocates a fixed-size buffer to store these parameters without adequate validation of their length. This classic buffer overflow condition allows an attacker to overwrite adjacent memory locations, potentially including return addresses, function pointers, or other critical control data structures. The vulnerability is classified as a CWE-121 stack-based buffer overflow, which occurs when data is copied into a stack buffer that is insufficiently sized to hold the input data. Attackers can exploit this by crafting command line arguments that exceed the allocated buffer space, causing the overflow to overwrite the program's execution flow. The specific nature of the flaw means that successful exploitation can lead to arbitrary code execution within the context of the crontab process, which typically runs with root privileges on AIX systems.
The operational impact of CVE-2007-4621 extends beyond simple privilege escalation, as it provides attackers with a persistent foothold within the system that can be leveraged for further compromise. Local users who can execute commands on the system can exploit this vulnerability to gain root access, effectively bypassing normal authentication mechanisms and system security controls. The exploitation process typically involves carefully crafted command line arguments that trigger the buffer overflow condition, potentially allowing attackers to inject malicious code that executes with elevated privileges. This vulnerability can be particularly dangerous in multi-user environments where local access is available, as it enables attackers to escalate their privileges without requiring additional authentication factors. The impact is further amplified by the fact that crontab is a commonly used system utility, making this vulnerability widely applicable across different AIX installations. The vulnerability also aligns with ATT&CK technique T1068, which covers privilege escalation through local exploits, and T1059, covering command and scripting interpreters.
Mitigation strategies for CVE-2007-4621 primarily focus on immediate system updates and configuration hardening measures. The most effective approach involves applying the official IBM AIX patches and updates that address the specific buffer overflow condition in the crontab utility. System administrators should also implement input validation controls and limit the ability of local users to interact with the crontab utility through restrictive access controls. Additional defensive measures include monitoring for suspicious command line argument patterns and implementing proper privilege separation for system utilities. The vulnerability demonstrates the importance of input validation and memory safety practices in system utilities, as highlighted by CWE-121 and related buffer overflow classifications. Organizations should also consider implementing automated patch management systems to ensure timely application of security updates, particularly for legacy operating systems like AIX 5.2. Regular security audits of system utilities and command line argument handling can help identify similar vulnerabilities that may exist in other system components, reducing overall attack surface and improving system resilience against privilege escalation attacks.