CVE-2005-4624 in PTnet ircd
Summary
by MITRE
The m_join function in channel.c for PTnet ircd 1.5 and 1.6 allows remote attackers to cause a denial of service (memory exhaustion that triggers a daemon restart) via a large number of requests to join a "charmed channel" such as PTnet, #PTnoticias and #*.log, which causes ircd to open the channel even though it does not have any valid users.
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Analysis
by VulDB Data Team • 08/01/2017
The vulnerability described in CVE-2005-4624 represents a critical denial of service weakness within the PTnet ircd 1.5 and 1.6 implementations that stems from improper handling of channel join operations. This flaw specifically affects the m_join function in the channel.c file, which processes user requests to join channels within the IRC network infrastructure. The vulnerability manifests when remote attackers exploit the channel joining mechanism by sending an excessive number of join requests to what are termed "charmed channels" such as PTnet, #PTnoticias, and #*.log. These particular channel names are significant because they are recognized by the PTnet network as special channels that require special handling within the ircd daemon.
The technical exploitation of this vulnerability occurs through a memory exhaustion attack pattern that specifically targets the ircd daemon's resource management capabilities. When the m_join function processes these excessive join requests, it continues to allocate memory resources to open channels even when those channels contain no legitimate users. This behavior creates a scenario where the daemon's memory consumption grows uncontrollably until system resources are exhausted, ultimately triggering an automatic daemon restart that disrupts network services for all connected users. The flaw demonstrates a classic lack of input validation and resource limiting mechanisms within the channel joining process, allowing attackers to consume system resources without proper bounds checking.
The operational impact of this vulnerability extends beyond simple service disruption to encompass broader network stability and availability concerns. Network administrators responsible for maintaining PTnet ircd services would experience frequent daemon restarts and potential service outages that could affect thousands of users simultaneously. The attack vector is particularly insidious because it does not require authentication or privileged access, making it accessible to any remote attacker with network connectivity to the affected ircd server. This vulnerability directly violates the principle of least privilege and demonstrates poor resource management practices that could lead to cascading failures within larger network infrastructures. The memory exhaustion condition creates a feedback loop where each additional join request consumes more resources, making the system increasingly unstable and eventually leading to complete service failure.
From a security perspective, this vulnerability aligns with CWE-400, which describes improper resource management in software systems, and can be categorized under ATT&CK technique T1499.1 for resource exhaustion attacks. The flaw represents a failure to implement proper rate limiting and resource allocation controls that are fundamental to maintaining system stability under attack conditions. Mitigation strategies should focus on implementing strict rate limiting mechanisms within the m_join function to prevent excessive channel join requests from consuming system resources. Network administrators should also consider implementing channel-specific access controls and resource quotas that limit the number of concurrent join operations. Additionally, the ircd implementation should incorporate proper memory management practices that include automatic resource cleanup and monitoring for anomalous resource consumption patterns. Regular security audits of daemon components and input validation routines would help identify similar vulnerabilities in other network services and prevent similar issues from arising in the future.