CVE-2002-1689 in AIX
Summary
by MITRE
Unknown vulnerability in the login program on AIX before 4.0 could allow remote users to specify 100 or more environment variables when logging on, which exceeds the length of a certain string, possibly triggering a buffer overflow.
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Analysis
by VulDB Data Team • 09/02/2019
The vulnerability identified as CVE-2002-1689 represents a classic buffer overflow condition within the AIX login program affecting systems prior to version 4.0. This issue stems from inadequate input validation mechanisms within the authentication process where the system fails to properly sanitize environment variable counts during user login operations. The flaw specifically manifests when remote users can manipulate the environment variable namespace to exceed predetermined string length limits, creating conditions ripe for exploitation.
From a technical perspective, this vulnerability operates as a buffer overflow through environment variable manipulation rather than traditional code injection vectors. The login program on AIX systems maintains internal buffers to store environment variable data during authentication sequences, and when users specify excessive environment variables exceeding 100 entries, the system's memory management fails to handle the overflow gracefully. This condition creates a scenario where adjacent memory regions become corrupted, potentially allowing attackers to execute arbitrary code or cause system instability. The vulnerability aligns with CWE-121, which describes buffer overflow conditions where insufficient bounds checking occurs in memory operations.
The operational impact of this vulnerability extends beyond simple system crashes or denial of service conditions. Remote attackers capable of establishing connections to AIX systems could leverage this weakness to escalate privileges, potentially gaining unauthorized access to sensitive system resources. The nature of the login program as a critical system component means that successful exploitation could provide attackers with persistent access to the target environment, making this vulnerability particularly dangerous in multi-user or enterprise settings. The vulnerability also demonstrates the importance of proper input validation and resource management in authentication mechanisms.
Security professionals should note that this vulnerability represents an early example of how environment variable handling can create security weaknesses in Unix-like systems. The issue highlights the need for comprehensive buffer management across all system components, particularly those handling user-provided data during authentication processes. Organizations should implement immediate patch management strategies to upgrade affected AIX systems to versions that properly validate environment variable counts and implement appropriate bounds checking. The vulnerability also underscores the importance of following secure coding practices and adhering to standards such as those outlined in the ATT&CK framework, particularly in the area of privilege escalation techniques and authentication bypass methods that attackers might employ against such buffer overflow conditions.