CVE-2003-1000 in Xchat
Summary
by MITRE
xchat 2.0.6 allows remote attackers to cause a denial of service (crash) via a passive DCC request with an invalid ID number, which causes a null dereference.
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Analysis
by VulDB Data Team • 06/17/2018
The vulnerability identified as CVE-2003-1000 affects xchat version 2.0.6, a popular internet relay chat client that was widely used for real-time communication across various network protocols. This particular flaw represents a classic null pointer dereference issue that occurs when the application fails to properly validate incoming data during the DCC file transfer process. The vulnerability specifically manifests when xchat receives a passive DCC request containing an invalid ID number, which triggers an unexpected crash condition that terminates the application's operation.
The technical mechanism behind this vulnerability stems from insufficient input validation within the DCC handling subsystem of xchat. When a malicious remote attacker sends a DCC request with an invalid ID number, the application attempts to process this malformed data without proper bounds checking or error handling. This leads to a null pointer dereference condition where the software tries to access memory at a null address, causing an immediate application crash. The vulnerability is classified as a type of memory corruption issue that falls under CWE-476, which specifically addresses null pointer dereference conditions in software applications.
From an operational perspective, this vulnerability presents a significant denial of service risk to users of the affected xchat version. The remote attack vector means that an adversary can exploit this flaw without requiring local system access or authentication, making it particularly dangerous in networked environments where chat clients are actively communicating. The impact extends beyond simple application instability, as users may lose ongoing chat sessions and potentially miss important communications during critical network operations. This vulnerability directly maps to ATT&CK technique T1499.004, which covers network denial of service attacks targeting application availability.
The exploitation of this vulnerability requires minimal technical skill and can be accomplished through automated tools that simply send malformed DCC requests to target systems. This makes it particularly dangerous as it can be weaponized by threat actors to disrupt communications across networks where xchat is deployed. The vulnerability affects not only individual users but also organizations that rely on chat-based communication systems, potentially leading to broader operational disruptions. Organizations using older versions of xchat or similar chat applications should consider immediate mitigation strategies including software updates, network segmentation, and implementing additional input validation measures to prevent exploitation of this and similar vulnerabilities.
Mitigation strategies for this vulnerability should include immediate deployment of updated xchat versions that contain proper input validation for DCC requests. System administrators should also implement network-level controls to monitor and filter suspicious DCC traffic patterns, while application-level firewalls can be configured to reject malformed requests before they reach the vulnerable application components. The fix typically involves adding robust validation checks for DCC ID numbers and implementing graceful error handling that prevents null pointer dereference conditions from occurring during normal operation. Organizations should also conduct regular vulnerability assessments to identify similar issues in other chat clients and communication software that may be susceptible to analogous memory corruption attacks.