CVE-2007-4623 in AIX
Summary
by MITRE
Stack-based buffer overflow in the sendrmt function in bellmail in IBM AIX 5.2 and 5.3 allows local users to execute arbitrary code via a long parameter to the m command.
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Analysis
by VulDB Data Team • 08/23/2019
The vulnerability identified as CVE-2007-4623 represents a critical stack-based buffer overflow flaw within the bellmail utility distributed with IBM AIX 5.2 and 5.3 operating systems. This vulnerability resides in the sendrmt function which handles remote mail transmission commands, specifically when processing the m command with excessively long parameters. The flaw stems from inadequate input validation and bounds checking mechanisms that fail to properly constrain the length of user-supplied data before copying it into fixed-size stack buffers. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, which occurs when a program writes more data to a buffer allocated on the stack than the buffer can accommodate, leading to memory corruption that can be exploited by malicious actors.
The operational impact of this vulnerability is severe as it provides local users with the capability to execute arbitrary code with the privileges of the bellmail process, which typically runs with elevated permissions due to its role in system mail operations. Attackers can exploit this weakness by crafting malicious input parameters that exceed the buffer boundaries, causing the stack to overflow and potentially overwrite return addresses, function pointers, or other critical stack data. This allows for arbitrary code execution within the context of the vulnerable process, potentially enabling privilege escalation or complete system compromise. The vulnerability is particularly dangerous because it requires only local access to exploit, making it accessible to any user with login privileges on the affected system.
The exploitation of this buffer overflow vulnerability aligns with ATT&CK technique T1068 which covers 'Exploitation for Privilege Escalation' and T1059 which covers 'Command and Scripting Interpreter'. The attack vector leverages the local execution environment where attackers can manipulate the m command parameter to trigger the overflow condition. The vulnerability demonstrates poor input validation practices that violate security best practices and can be mitigated through proper bounds checking, stack canaries, and address space layout randomization. Organizations should implement immediate patches from IBM addressing the buffer overflow in bellmail, while also establishing monitoring for unusual mail system activity and ensuring that local user privileges are properly restricted to minimize potential exploitation impact.
This vulnerability highlights the importance of proper memory management and input validation in system utilities, particularly those with elevated privileges. The flaw represents a classic example of how insufficient bounds checking in legacy code can create persistent security risks that remain exploitable for years after initial discovery. System administrators should prioritize patch management and consider implementing additional security controls such as mandatory access controls and privilege separation to reduce the attack surface and limit potential damage from similar vulnerabilities. The issue also underscores the need for comprehensive security testing of system utilities and the importance of adhering to secure coding practices throughout the software development lifecycle.