CVE-2002-0741 in psyBNC
Summary
by MITRE
psyBNC 2.3 allows remote attackers to cause a denial of service (CPU consumption and resource exhaustion) by sending a PASS command with a long password argument and quickly killing the connection, which is not properly terminated by psyBNC.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 09/14/2025
The vulnerability identified as CVE-2002-0741 affects psyBNC version 2.3, a popular IRC bouncer application that allows users to maintain persistent connections to IRC networks while their clients are disconnected. This issue represents a classic resource exhaustion attack pattern that exploits improper connection handling mechanisms within the bouncer software. The vulnerability specifically manifests when an attacker sends a PASS command with an excessively long password argument followed immediately by connection termination, creating a scenario where the application fails to properly clean up resources associated with the connection.
The technical flaw resides in the application's inadequate handling of malformed or excessively long input parameters during the authentication process. When a PASS command containing an unusually long password is received, psyBNC allocates memory resources to process this input without proper bounds checking or resource management. The subsequent rapid connection termination prevents the application from properly executing cleanup routines that would normally release allocated memory and system resources. This creates a memory leak condition where resources remain allocated even after the connection is closed, leading to progressive resource consumption over time.
From an operational perspective, this vulnerability enables remote attackers to perform denial of service attacks that consume excessive CPU cycles and system resources, ultimately leading to system instability or complete service unavailability. The attack is particularly effective because it requires minimal resources to execute - simply sending a long password string followed by connection termination is sufficient to trigger the vulnerability. This makes it a low-effort, high-impact attack vector that can be automated and scaled against multiple targets simultaneously, potentially affecting the availability of IRC services that depend on psyBNC for connectivity management.
The vulnerability aligns with CWE-400, which addresses improper resource management in software applications, and demonstrates characteristics consistent with the ATT&CK technique T1499.004 for network denial of service attacks. The attack pattern follows a resource exhaustion methodology that targets the application's inability to properly handle exceptional input conditions and cleanup operations. Security practitioners should note that this vulnerability represents an early example of how improper input validation and resource management can lead to denial of service conditions in network services, highlighting the critical importance of robust error handling and resource cleanup mechanisms in server applications.
Mitigation strategies should focus on implementing proper input validation and bounds checking for all authentication parameters, particularly password fields. System administrators should upgrade to patched versions of psyBNC where available, or implement connection rate limiting and resource monitoring to detect unusual CPU consumption patterns. Network-level protections such as firewall rules that limit connection frequency and connection timeout configurations can help reduce the impact of such attacks. Additionally, application-level monitoring should be implemented to detect and alert on abnormal resource usage patterns that may indicate exploitation attempts. The vulnerability underscores the necessity of proper resource management practices and input sanitization in network services to prevent attackers from exploiting memory and CPU consumption issues.