CVE-2000-0661 in IRC Server
Summary
by MITRE
WircSrv IRC Server 5.07s allows remote attackers to cause a denial of service via a long string to the server port.
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Analysis
by VulDB Data Team • 10/13/2025
The vulnerability identified as CVE-2000-0661 affects WircSrv IRC Server version 5.07s and represents a classic buffer overflow condition that can be exploited to trigger a denial of service attack. This flaw occurs when the server processes incoming data from network connections without proper input validation or length checking, creating an opportunity for remote attackers to send maliciously crafted data that exceeds the allocated buffer space. The vulnerability specifically manifests when a long string is transmitted to the server port, causing the application to crash or become unresponsive.
From a technical perspective this vulnerability aligns with CWE-121, which describes buffer overflow conditions where insufficient space is allocated for data, and CWE-122, which addresses buffer overflow vulnerabilities that occur when data is copied or moved into a buffer without proper bounds checking. The flaw represents a fundamental issue in input validation where the server fails to implement proper data sanitization before processing user-supplied information. The WircSrv server implementation does not perform adequate bounds checking on incoming strings, allowing an attacker to craft a payload that exceeds the buffer capacity and subsequently corrupts memory structures or causes the application to terminate unexpectedly.
The operational impact of this vulnerability extends beyond simple service disruption as it can be exploited by remote attackers without requiring authentication or specialized privileges. An attacker can simply connect to the server port and send a specially crafted long string to trigger the denial of service condition. This makes the vulnerability particularly dangerous as it can be exploited by anyone with network access to the server, potentially leading to extended service outages that affect legitimate users and can be used as part of larger attack campaigns. The vulnerability affects the availability aspect of the CIA triad by preventing legitimate users from accessing the IRC services.
The attack pattern associated with this vulnerability follows the MITRE ATT&CK framework's technique T1499, which covers network denial of service attacks. The exploitation process involves sending malformed data to the server port, which results in the application crashing and requiring manual restart to restore service. This makes the vulnerability particularly problematic for mission-critical IRC services where uptime is essential. Organizations using WircSrv 5.07s should implement immediate mitigations including input validation controls, network segmentation, and monitoring for unusual connection patterns that might indicate exploitation attempts.
Mitigation strategies should focus on both immediate defensive measures and long-term architectural improvements. The most effective immediate solution involves applying patches or updates from the vendor if available, though this specific version appears to be obsolete and may not receive security updates. Network-level protections such as firewall rules that limit connection rates and implement input filtering can help reduce the risk of exploitation. Additionally, implementing proper input validation mechanisms within the application layer can prevent the buffer overflow condition from occurring. Regular monitoring and logging of server connections can help detect potential exploitation attempts before they cause service disruption. Organizations should also consider migrating to more modern IRC server implementations that have robust security features and active maintenance cycles to prevent similar vulnerabilities from occurring in the future.