CVE-2012-6697 in InspIRCd
Summary
by MITRE
InspIRCd before 2.0.7 allows remote attackers to cause a denial of service (infinite loop).
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Analysis
by VulDB Data Team • 11/29/2022
The vulnerability identified as CVE-2012-6697 affects InspIRCd versions prior to 2.0.7, representing a critical denial of service flaw that can be exploited by remote attackers to disrupt service availability. This issue manifests as an infinite loop condition within the IRC server software, which fundamentally compromises the system's ability to process legitimate client connections and maintain operational stability. The vulnerability exists in the protocol handling mechanisms of InspIRCd, specifically in how the software processes certain malformed or crafted input sequences from network clients.
The technical flaw stems from insufficient input validation and inadequate state management within the IRC server's message processing pipeline. When malicious clients send specially crafted IRC commands or messages that trigger specific parsing conditions, the server enters an infinite loop where it repeatedly processes the same malformed input without proper termination conditions. This behavior aligns with CWE-835, which categorizes infinite loops as a class of vulnerabilities that can lead to resource exhaustion and service disruption. The loop occurs at the protocol parsing layer where the server fails to properly handle edge cases in command interpretation, causing it to repeatedly execute the same processing routine without advancing to subsequent commands or connections.
From an operational perspective, this vulnerability presents a severe risk to IRC network stability and availability. Remote attackers can exploit this flaw by connecting to the vulnerable InspIRCd server and sending carefully constructed commands that trigger the infinite loop condition. Once activated, the server consumes excessive CPU resources as it continuously processes the malformed input, effectively rendering the service unavailable to legitimate users. The impact extends beyond simple service disruption, as the infinite loop can cause the server to become unresponsive to all incoming connections, including those from administrators attempting to mitigate the attack or restore service. This vulnerability particularly affects IRC networks that rely on InspIRCd as their primary server software, potentially compromising entire network infrastructures and disrupting communication channels for users across the affected systems.
The mitigation strategy for CVE-2012-6697 requires immediate deployment of InspIRCd version 2.0.7 or later, which includes patches addressing the infinite loop condition in the protocol handling code. System administrators should implement network-level protections such as rate limiting and connection throttling to reduce the impact of potential exploitation attempts. Additionally, monitoring solutions should be configured to detect unusual CPU consumption patterns that may indicate exploitation of this vulnerability. The fix implemented in version 2.0.7 involves enhanced input validation and proper loop termination conditions within the IRC protocol parser, ensuring that malformed commands do not trigger infinite processing cycles. Organizations should also consider implementing intrusion detection systems that can identify suspicious IRC traffic patterns associated with this specific vulnerability. This vulnerability demonstrates the importance of proper input validation and state management in network services, aligning with ATT&CK technique T1499.004 for network denial of service attacks and highlighting the need for robust error handling in protocol implementations.