CVE-2008-1501 in ircu
Summary
by MITRE
The send_user_mode function in s_user.c in (1) Undernet ircu 2.10.12.12 and earlier, (2) snircd 1.3.4 and earlier, and unspecified other ircu derivatives allows remote attackers to cause a denial of service (daemon crash) via a malformed MODE command.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 10/20/2024
The vulnerability described in CVE-2008-1501 represents a critical denial of service flaw affecting multiple IRC daemon implementations based on the ircu codebase. This issue resides within the send_user_mode function located in the s_user.c file, which handles user mode changes in the IRC protocol. The vulnerability specifically manifests when processing malformed MODE commands, which are standard IRC protocol commands used to set user modes and channel modes. The flaw affects Undernet ircu version 2.10.12.12 and earlier versions, snircd version 1.3.4 and earlier, along with unspecified derivatives of the ircu codebase that share similar implementation patterns.
The technical nature of this vulnerability stems from inadequate input validation within the send_user_mode function, which fails to properly sanitize or validate the parameters of incoming MODE commands. When a remote attacker crafts a malicious MODE command with malformed parameters, the function processes this input without proper bounds checking or parameter validation, leading to undefined behavior that ultimately causes the IRC daemon to crash and restart. This type of vulnerability falls under CWE-129, which describes improper validation of array indices, and represents a classic buffer overread or memory corruption scenario where the daemon attempts to access memory locations beyond the allocated buffer boundaries. The vulnerability demonstrates a fundamental lack of defensive programming practices in handling user-provided data within the core protocol processing functions.
The operational impact of this vulnerability extends beyond simple service disruption, as it provides attackers with a reliable method to repeatedly crash IRC servers and disrupt communications for all connected users. This denial of service attack can be executed remotely without authentication requirements, making it particularly dangerous in public IRC networks where multiple servers may be affected simultaneously. The crash typically results in complete service unavailability until system administrators manually restart the daemon processes, potentially causing significant disruption to IRC communities and network operations. From an adversary perspective, this vulnerability aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and represents a common vector for disrupting network infrastructure services. The vulnerability affects the availability aspect of the CIA triad, as it prevents legitimate users from accessing the IRC service.
Mitigation strategies for this vulnerability require immediate patching of affected IRC daemon implementations to address the input validation deficiencies in the send_user_mode function. System administrators should prioritize updating their IRC server software to versions that contain proper input sanitization and bounds checking mechanisms. Additionally, network-level protections such as rate limiting and connection filtering can provide temporary defense against exploitation attempts while patches are deployed. The fix typically involves implementing proper parameter validation, adding bounds checking to array accesses, and ensuring that all user-provided input is thoroughly sanitized before processing. Organizations should also consider implementing intrusion detection systems that can identify and alert on malformed MODE commands, providing early warning of potential exploitation attempts. The vulnerability highlights the importance of maintaining up-to-date software versions and implementing robust input validation practices in network services to prevent similar issues from occurring in other protocol implementations.