CVE-2007-4405 in ircu
Summary
by MITRE
ircu 2.10.12.02 through 2.10.12.04 allows remote attackers to cause a denial of service (memory and bandwidth consumption) by creating a large number of unused channels (zannels).
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Analysis
by VulDB Data Team • 09/07/2018
The vulnerability identified as CVE-2007-4405 affects ircu versions 2.10.12.02 through 2.10.12.04, representing a significant denial of service weakness that exploits the protocol's channel management mechanisms. This issue falls under the category of resource exhaustion attacks where malicious actors can consume system resources through legitimate protocol operations. The vulnerability specifically targets the channel creation and management functions within the IRC server implementation, allowing remote attackers to exploit the system by creating numerous unused channels that persist in memory and consume bandwidth resources. The flaw demonstrates a critical design oversight in how the server handles channel lifecycle management, particularly in scenarios where channels are created but never properly utilized or cleaned up.
The technical implementation of this vulnerability stems from inadequate validation and resource management within the ircu server's channel handling code. When attackers create multiple channels without any active participants or meaningful content, the server maintains these channel structures in memory indefinitely, leading to progressive memory consumption that can eventually exhaust available resources. This behavior aligns with CWE-400, which categorizes unchecked resource consumption as a common vulnerability pattern in software systems. The memory leak occurs because the server does not implement proper channel cleanup mechanisms or resource limits for unused channels, allowing attackers to maintain persistent references to these structures even when they serve no functional purpose.
The operational impact of this vulnerability extends beyond simple resource exhaustion to potentially compromise the entire IRC infrastructure. Servers affected by this vulnerability can experience gradual performance degradation followed by complete service unavailability as memory consumption reaches critical levels. Network bandwidth is also consumed unnecessarily through the maintenance of these unused channel structures, which may include regular updates, announcements, or protocol communications related to these channels. The attack can be executed with minimal resources and technical expertise, making it particularly dangerous for public IRC servers that may be targeted by automated tools or malicious actors seeking to disrupt services. This vulnerability directly impacts the availability aspect of the CIA triad and can be classified under the ATT&CK technique T1499.004 for network denial of service attacks.
Mitigation strategies for CVE-2007-4405 require both immediate and long-term approaches to address the underlying resource management issues. Immediate fixes include implementing channel cleanup mechanisms that automatically remove unused channels after a specified period of inactivity or setting maximum limits on the number of channels that can be created by individual users or globally. Configuration changes should include enabling automatic channel cleanup policies and implementing resource quotas to prevent single users from consuming excessive system resources. The most effective long-term solution involves upgrading to ircu versions that have addressed this vulnerability through proper resource management and channel lifecycle controls. System administrators should also implement monitoring and alerting mechanisms to detect unusual channel creation patterns and resource consumption spikes that may indicate exploitation attempts. Additionally, network-level controls such as rate limiting and connection throttling can help reduce the impact of such attacks by limiting the rate at which new channels can be created, thereby preventing rapid resource exhaustion attacks.