CVE-2002-0332 in xtell
Summary
by MITRE
Buffer overflows in xtell (xtelld) 1.91.1 and earlier, and 2.x before 2.7, allows remote attackers to execute arbitrary code via (1) a long DNS hostname that is determined using reverse DNS lookups, (2) a long AUTH string, or (3) certain data in the xtell request.
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Analysis
by VulDB Data Team • 12/17/2024
The vulnerability identified as CVE-2002-0332 represents a critical buffer overflow flaw affecting the xtell service implementation in xtelld versions 1.91.1 and earlier, as well as version 2.x before 2.7. This security weakness stems from inadequate input validation and memory management within the xtell daemon, which processes network requests from remote clients. The vulnerability manifests when the service receives malformed input data that exceeds allocated buffer boundaries, creating potential execution paths for malicious code injection. The flaw specifically impacts the reverse DNS lookup functionality and authentication string processing mechanisms, making it particularly dangerous in networked environments where remote access is permitted. The buffer overflow conditions occur during the parsing of network requests, where the service fails to properly sanitize or limit input lengths before copying data into fixed-size memory buffers.
The technical implementation of this vulnerability follows established patterns that align with common software security flaws categorized under CWE-121, which addresses stack-based buffer overflow conditions. The attack vectors identified in the CVE description demonstrate multiple entry points for exploitation, including long DNS hostnames processed through reverse DNS lookups, extended AUTH strings, and malformed data within xtell requests. These vectors leverage the fundamental weakness in memory management where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The reverse DNS lookup scenario particularly exploits the trust placed in DNS resolution processes, where a maliciously crafted hostname can trigger the buffer overflow during the resolution phase. The AUTH string vulnerability demonstrates how authentication mechanisms can be weaponized when input validation is insufficient, allowing attackers to inject malicious data that exceeds buffer limits. The third vector involving xtell request data suggests that the service's overall request parsing logic lacks proper input length constraints, creating multiple opportunities for exploitation.
From an operational perspective, this vulnerability presents significant risk to systems running vulnerable versions of xtelld, as it enables remote code execution without requiring authentication. The impact extends beyond simple service disruption to potentially provide attackers with complete system compromise capabilities. Network administrators and security professionals must recognize that systems utilizing the xtell service in environments where remote access is permitted represent high-value targets for exploitation. The vulnerability's exploitability increases in scenarios where the service operates on public networks or is accessible from untrusted networks, as attackers can leverage the buffer overflow conditions from remote locations. The lack of authentication requirements for exploitation means that any system running vulnerable versions of xtelld is immediately at risk, regardless of network segmentation or firewall configurations. This makes the vulnerability particularly concerning for internet-facing services and systems where the xtell functionality is exposed to external networks.
Mitigation strategies for CVE-2002-0332 should prioritize immediate software updates to versions 2.7 or later, which contain the necessary patches addressing the buffer overflow conditions. System administrators must conduct comprehensive inventory assessments to identify all systems running vulnerable versions of xtelld, particularly in legacy environments where software updates may be delayed or restricted. Network segmentation and firewall rules should be implemented to restrict access to xtell services, limiting exposure to trusted networks only. Additionally, input validation measures should be enhanced at network boundaries to filter out potentially malicious input data, including overly long DNS hostnames and authentication strings. The implementation of intrusion detection systems capable of identifying patterns associated with buffer overflow attempts can provide additional layers of defense. Security monitoring should focus on unusual network traffic patterns that may indicate exploitation attempts, particularly around DNS resolution and authentication request processing. Organizations should also consider implementing application-level firewalls or proxy services that can perform additional input sanitization before requests reach the vulnerable service. The remediation process should include thorough testing of patched versions to ensure that the vulnerability has been properly addressed without introducing new operational issues. Regular security assessments and vulnerability scanning should be conducted to identify any remaining instances of vulnerable software within the organization's infrastructure.