CVE-1999-0679 in Ircd
Summary
by MITRE
Buffer overflow in hybrid-6 IRC server commonly used on EFnet allows remote attackers to execute commands via m_invite invite option.
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Analysis
by VulDB Data Team • 12/07/2024
The vulnerability described in CVE-1999-0679 represents a critical buffer overflow flaw discovered in the hybrid-6 IRC server software that was widely deployed across the EFnet IRC network. This particular implementation flaw existed within the m_invite command processing functionality, which is used to invite users to IRC channels. The hybrid-6 server, being one of the most popular IRC server implementations during the late 1990s, was extensively used by numerous IRC networks and organizations, making this vulnerability particularly dangerous as it could affect a large number of connected users and networks simultaneously.
The technical nature of this buffer overflow occurs when the hybrid-6 server processes the m_invite command with malformed input data in the invite option parameter. When an attacker sends a specially crafted invite command containing excessive data in the invite option field, the server fails to properly validate the input length before copying it into a fixed-size buffer. This classic buffer overflow condition allows the attacker to overwrite adjacent memory locations, potentially including return addresses, function pointers, or other critical program state information. The vulnerability specifically targets the server's command processing loop where the invite option parameter is handled without adequate bounds checking, creating a scenario where attacker-controlled data can overwrite program execution flow.
The operational impact of this vulnerability extends far beyond simple denial of service conditions, as it provides remote attackers with the capability to execute arbitrary commands on the compromised IRC server. This means that an attacker who successfully exploits this vulnerability could gain full control over the affected server, potentially allowing them to manipulate channel memberships, broadcast malicious messages, redirect users to compromised servers, or even use the compromised server as a launch point for attacks against other network resources. The implications are particularly severe given that many IRC servers served as central communication hubs for various organizations, communities, and networks, making them attractive targets for malicious actors seeking persistent access to larger network infrastructures.
Mitigation strategies for this vulnerability require immediate implementation of software patches provided by the hybrid-6 developers, as well as network-level protective measures such as input validation and access control restrictions. Organizations should implement proper input sanitization at all network interfaces and command processing points to prevent buffer overflow conditions from occurring. Additionally, this vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and demonstrates characteristics consistent with ATT&CK technique T1059.007 for command and scripting interpreter. Network administrators should also consider implementing intrusion detection systems to monitor for suspicious invite command patterns and establish robust network segmentation to limit the potential impact of successful exploitation. The vulnerability serves as a historical example of how critical buffer overflow flaws in widely-used network services can create widespread security risks across interconnected systems.