CVE-2002-0197 in psyBNC
Summary
by MITRE
psyBNC 2.3 beta and earlier allows remote attackers to spoof encrypted, trusted messages by sending lines that begin with the "[B]" sequence, which makes the message appear legitimate.
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Analysis
by VulDB Data Team • 09/22/2025
The psyBNC vulnerability described in CVE-2002-0197 represents a significant security flaw in the psyBNC IRC bouncer software version 2.3 beta and earlier. This vulnerability specifically targets the message authentication and validation mechanisms within the bouncer system, creating a critical weakness that allows remote attackers to manipulate message integrity. The flaw exists in how the software processes and validates incoming messages, particularly those that are encrypted and intended to be trusted by the system.
The technical implementation of this vulnerability relies on the specific sequence "[B]" which serves as a trigger for the spoofing mechanism. When an attacker sends a message beginning with this sequence, the psyBNC software incorrectly interprets the message as legitimate and trusted, bypassing normal validation procedures that should verify message authenticity. This particular sequence acts as a delimiter or marker that the software uses to identify encrypted messages, but the implementation fails to properly validate that such messages actually originate from trusted sources. The vulnerability stems from insufficient input sanitization and validation within the message processing pipeline, creating an injection point that allows attackers to manipulate the trust model of the system.
The operational impact of this vulnerability extends beyond simple message spoofing, as it fundamentally compromises the integrity of communications within the IRC network. Attackers can potentially impersonate legitimate users, send malicious commands, or manipulate the flow of information between connected clients and servers. This capability undermines the security assumptions that users rely on when using psyBNC, particularly in environments where encrypted communications are expected to maintain confidentiality and authenticity. The vulnerability affects the core trust relationships within the bouncer system, potentially allowing attackers to gain unauthorized access to sensitive channels or manipulate communication flows in ways that could compromise entire IRC networks.
This vulnerability aligns with CWE-20, which describes improper input validation, and represents a classic case of trust abuse within a security system. The flaw demonstrates how improper handling of message formatting can create security holes that allow attackers to bypass authentication mechanisms. From an ATT&CK perspective, this vulnerability maps to techniques involving command and control communication manipulation and credential access through message manipulation. Organizations using psyBNC should implement immediate mitigations including updating to versions that address this vulnerability, implementing additional message validation layers, and potentially deploying network monitoring to detect anomalous "[B]" sequence usage. The vulnerability also highlights the importance of proper input validation in security-critical systems and serves as a reminder that even seemingly innocuous formatting characters can create significant security risks when not properly validated.