CVE-2007-4411 in ircu
Summary
by MITRE
ircu 2.10.12.05 and earlier allows remote attackers to discover the hidden IP address of arbitrary +x users via a series of /silence commands with (1) CIDR mask arguments or (2) certain other arguments that represent groups of IP addresses, then monitoring CTCP ping replies.
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Analysis
by VulDB Data Team • 09/07/2018
The vulnerability described in CVE-2007-4411 affects ircu version 2.10.12.05 and earlier, representing a significant information disclosure flaw within the IRC protocol implementation. This vulnerability specifically targets the handling of user privacy mechanisms, particularly those related to the +x user mode which conceals IP addresses from other users on the network. The flaw exploits a weakness in how the server processes silence commands and responds to CTCP ping requests, creating an indirect method for attackers to bypass intended privacy protections. The vulnerability operates through a sophisticated technique that combines multiple command sequences with specific argument formats to systematically uncover hidden IP addresses.
The technical execution of this vulnerability involves the strategic use of /silence commands with CIDR mask arguments or other group-based IP address representations to manipulate the server's response behavior. When an attacker sends these carefully crafted silence commands followed by monitoring CTCP ping replies, they can correlate the responses to deduce the true IP addresses of users who have enabled the +x mode for privacy protection. This method exploits a fundamental flaw in the server's access control and response handling mechanisms, where the silence command processing does not properly account for the privacy implications of its interactions with other protocol elements. The vulnerability is classified under CWE-200, which deals with information exposure, and represents a specific instance of how improper access control can lead to unauthorized information disclosure.
The operational impact of this vulnerability extends beyond simple information disclosure, as it undermines the core privacy protections that users expect when connecting to IRC networks. Attackers can systematically discover the network locations of users who have explicitly enabled privacy modes, potentially exposing them to targeted attacks, DoS attempts, or other malicious activities. The vulnerability affects the integrity of the IRC protocol's privacy model, where users rely on server-side mechanisms to protect their IP addresses from unauthorized discovery. This flaw can be particularly damaging in environments where IRC is used for sensitive communications or where users require anonymity for legitimate reasons such as research, activism, or secure communication.
Mitigation strategies for this vulnerability require immediate patching of affected ircu installations to version 2.10.12.06 or later, which contains the necessary fixes for the silence command processing and CTCP response handling. Network administrators should also implement monitoring for unusual silence command patterns and CTCP traffic that might indicate exploitation attempts. The vulnerability demonstrates the importance of proper input validation and access control in protocol implementations, aligning with ATT&CK technique T1071.004 for application layer protocol manipulation. Organizations should also consider implementing additional network-level protections and monitoring to detect and prevent exploitation attempts, while ensuring that privacy-enhancing features are properly configured and tested to maintain the expected security posture for all users.