CVE-2003-0696 in AIX
Summary
by MITRE
The getipnodebyname() API in AIX 5.1 and 5.2 does not properly close sockets, which allows attackers to cause a denial of service (resource exhaustion).
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Analysis
by VulDB Data Team • 01/14/2018
The vulnerability described in CVE-2003-0696 represents a critical resource management flaw within the AIX operating system's networking stack. This issue specifically affects AIX versions 5.1 and 5.2, where the getipnodebyname() application programming interface fails to properly close network sockets after use. The root cause of this vulnerability aligns with CWE-404, which categorizes improper resource cleanup or release, and demonstrates a classic example of socket descriptor leakage that can be exploited by malicious actors. The flaw exists in the system's network resolution functionality where applications relying on this API for hostname resolution may inadvertently leave socket connections open, creating a persistent resource drain that can escalate to system instability.
The technical implementation of this vulnerability stems from the improper handling of socket lifecycle management within the getipnodebyname() function. When applications make calls to this API to resolve hostnames, the underlying socket connections are established for the resolution process but are not correctly closed upon completion. This results in a gradual accumulation of open socket descriptors that remain in the system's file descriptor table. Each unclosed socket consumes system resources including memory allocation, file descriptor table entries, and potentially network connection tracking resources. The vulnerability operates at the system call level where socket operations are performed, making it particularly dangerous as it affects the fundamental networking capabilities of the operating system. The flaw can be categorized under the ATT&CK technique T1499.004, which involves network denial of service attacks through resource exhaustion.
The operational impact of this vulnerability extends beyond simple resource consumption to potentially compromise entire system availability. As attackers repeatedly invoke the getipnodebyname() API with malicious or malformed input, they can systematically exhaust the system's available socket descriptors and file handles. This resource exhaustion can manifest as applications failing to establish new network connections, system performance degradation, or complete system unresponsiveness. The vulnerability is particularly concerning in server environments where network services continuously handle hostname resolution requests, as the cumulative effect of socket leakage can quickly overwhelm system resources. The attack vector is relatively simple to exploit since it only requires repeated calls to the vulnerable API, making it accessible to attackers with minimal technical expertise while still delivering significant operational impact.
Mitigation strategies for CVE-2003-0696 should focus on both immediate system hardening and long-term architectural improvements. The most direct approach involves applying the vendor-provided security patches or updates that correct the socket closure logic within the getipnodebyname() implementation. System administrators should also implement monitoring solutions to track socket descriptor usage and file handle consumption patterns to detect potential exploitation attempts. Network administrators can deploy rate limiting measures and connection tracking rules to prevent rapid socket exhaustion attacks. Additionally, applications should be audited for proper socket management practices, ensuring that all network connections are explicitly closed after use regardless of the API being called. The vulnerability highlights the importance of following secure coding practices as outlined in the CERT Secure Coding Standards, particularly those related to resource management and proper cleanup procedures. Organizations should also consider implementing automated system health monitoring to detect unusual resource consumption patterns that may indicate exploitation of similar vulnerabilities.