CVE-2001-0763 in xinetd
Summary
by MITRE
Buffer overflow in Linux xinetd 2.1.8.9pre11-1 and earlier may allow remote attackers to execute arbitrary code via a long ident response, which is not properly handled by the svc_logprint function.
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Analysis
by VulDB Data Team • 12/01/2024
The vulnerability identified as CVE-2001-0763 represents a critical buffer overflow flaw within the Linux xinetd service daemon version 2.1.8.9pre11-1 and earlier releases. This vulnerability specifically affects the svc_logprint function which is responsible for handling log messages within the xinetd daemon. The buffer overflow occurs when processing ident responses from remote systems, creating a condition where maliciously crafted long ident responses can overwrite adjacent memory locations in the daemon process. This flaw exists due to inadequate input validation and bounds checking within the logging mechanism, allowing attackers to potentially overwrite critical program memory including return addresses and function pointers.
The technical implementation of this vulnerability stems from the improper handling of user-supplied data within the svc_logprint function. When xinetd receives an ident response from a connecting client, it processes this information without sufficient bounds checking to prevent buffer overflows. The flaw manifests when an attacker sends an ident response that exceeds the allocated buffer size, causing adjacent memory to be overwritten. This type of vulnerability falls under CWE-121, which describes stack-based buffer overflow conditions, and specifically relates to CWE-787, representing out-of-bounds write vulnerabilities. The attack vector operates through network connections where the xinetd daemon is configured to handle ident lookups, making it particularly dangerous in environments where xinetd services are exposed to untrusted networks.
The operational impact of CVE-2001-0763 is severe and potentially catastrophic for affected systems. Successful exploitation allows remote attackers to execute arbitrary code with the privileges of the xinetd process, which typically runs with elevated permissions. This can lead to complete system compromise, privilege escalation, and persistent access to the compromised host. The vulnerability affects systems where xinetd is actively running and configured to process ident responses, particularly in environments where services are exposed to external networks without proper network segmentation. Attackers can leverage this vulnerability to gain unauthorized access, establish backdoors, or perform further reconnaissance and lateral movement within compromised networks. The impact is consistent with ATT&CK technique T1068, which involves exploiting vulnerabilities to gain system compromise, and T1059, representing execution through command injection.
Mitigation strategies for CVE-2001-0763 require immediate action to address the vulnerable xinetd version. The primary remediation involves upgrading to xinetd version 2.1.8.9pre11-1 or later, where the buffer overflow has been patched. Organizations should also implement network segmentation to limit exposure of xinetd services to untrusted networks and disable unnecessary ident lookups where possible. Additional defensive measures include monitoring for anomalous ident responses and implementing intrusion detection systems to detect potential exploitation attempts. System administrators should conduct thorough vulnerability assessments to identify all instances of vulnerable xinetd installations and ensure proper patch management processes are in place to prevent similar vulnerabilities from arising in the future. The vulnerability serves as a reminder of the critical importance of input validation and memory safety in system-level software components that handle untrusted network data.