CVE-2000-0594 in IRC Client
Summary
by MITRE
BitchX IRC client does not properly cleanse an untrusted format string, which allows remote attackers to cause a denial of service via an invite to a channel whose name includes special formatting characters.
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Analysis
by VulDB Data Team • 12/09/2024
The vulnerability identified as CVE-2000-0594 affects the BitchX IRC client, a popular open-source Internet Relay Chat implementation that was widely used in the late 1990s and early 2000s. This flaw represents a classic format string vulnerability that demonstrates the critical importance of proper input validation and sanitization in networked applications. The vulnerability specifically resides in how the client processes channel names during invitation operations, creating a scenario where maliciously crafted channel names can exploit the application's formatting mechanisms.
The technical flaw manifests when the BitchX client receives an invitation to join a channel whose name contains special formatting characters such as percent signs, which are typically used in format strings to indicate variable substitution. When the client attempts to display this channel name in its user interface or log messages, it fails to properly sanitize the input before passing it to formatting functions like printf or similar string manipulation routines. This improper handling allows attackers to inject format specifiers that the application processes as actual formatting directives rather than literal text, leading to unpredictable behavior in the application's memory management and execution flow.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable more sophisticated attacks depending on the specific implementation details and memory layout. When a remote attacker sends an invitation containing specially crafted format string characters, the client's processing routine can be manipulated to either crash the application entirely, causing a denial of service that disrupts communication for all users, or potentially execute arbitrary code if the format string allows for memory address manipulation. This type of vulnerability falls under CWE-134 which specifically addresses the use of format strings with user-supplied data, and it aligns with ATT&CK technique T1203 which covers legitimate program execution through command injection.
The vulnerability demonstrates how seemingly innocuous user interface elements can become attack vectors when proper input sanitization is omitted. In IRC environments where channel names are frequently shared and displayed, this flaw could be exploited by attackers to repeatedly disrupt client operations or potentially gain unauthorized access to system resources. The attack requires minimal sophistication as it only necessitates sending a specially formatted invitation message, making it particularly dangerous in environments where users might receive invitations from untrusted sources. Organizations using legacy IRC clients or those that have not properly patched this vulnerability should consider immediate remediation measures including updating to patched versions, implementing network-level filtering of suspicious channel names, or deploying additional monitoring to detect exploitation attempts.