CVE-2004-1395 in No One Lives Forever 2
Summary
by MITRE
The Lithtech engine, as used in (1) Contract Jack 1.1 and earlier, (2) No one lives forever 2 1.3 and earlier, (3) Tron 2.0 1.042 and earlier, (4) F.E.A.R. (First Encounter Assault and Recon), and possibly other games, allows remote attackers to cause a denial of service (connection refused) via a UDP packet that causes recvfrom to generate a return code that causes the listening loop to exit, as demonstrated using zero byte packets or packets between 8193 and 12280 bytes, which result in conditions that are not "Operation would block."
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Analysis
by VulDB Data Team • 07/27/2025
The vulnerability described in CVE-2004-1395 represents a critical denial of service flaw within the Lithtech game engine that affected multiple popular titles including Contract Jack, No one lives forever 2, Tron 2.0, and F.E.A.R. This vulnerability stems from improper handling of UDP packet processing within the engine's network communication loop, creating a condition where maliciously crafted network traffic can cause the game server or client to terminate its listening process. The flaw specifically manifests when the recvfrom system call returns unexpected error codes that are not properly accounted for in the engine's network processing logic, leading to abrupt termination of the network service.
The technical implementation of this vulnerability exploits the way the Lithtech engine handles incoming UDP packets through its network reception loop. When packets of specific sizes - particularly zero byte packets or packets ranging between 8193 and 12280 bytes - are received, the recvfrom function generates return codes that do not correspond to the expected "Operation would block" condition. This deviation from normal operation causes the engine's listening loop to exit prematurely, resulting in connection refusal and complete service disruption. The vulnerability demonstrates poor error handling practices in network socket programming where the code does not adequately validate or handle all possible return values from system calls, a common pattern identified in CWE-248.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the entire gaming experience for users connected to affected servers. Game administrators and players could experience complete loss of connectivity, with no ability to establish new connections or maintain existing sessions. This makes the vulnerability particularly dangerous in multiplayer gaming environments where server stability is crucial for maintaining game sessions and player engagement. The specific packet size ranges indicate that the vulnerability is not merely a simple buffer overflow but rather a more nuanced issue related to how the engine's network stack handles edge cases in packet size validation and error condition processing.
This vulnerability aligns with ATT&CK technique T1498 which focuses on network denial of service attacks and demonstrates the importance of robust input validation in network services. The issue specifically relates to CWE-704 which covers improper handling of system call return values, and CWE-121 which addresses stack-based buffer overflow conditions. The flaw represents a classic example of how insufficient error handling in network programming can lead to complete service termination, making it a prime candidate for exploitation in coordinated denial of service attacks against gaming servers. Organizations should implement proper input validation and error handling mechanisms to prevent similar issues, particularly when dealing with network socket operations that must handle arbitrary data from untrusted sources. The vulnerability also highlights the need for comprehensive testing of edge cases in network protocols, particularly around buffer sizes and error conditions that may not be encountered during normal operation but can be exploited to cause service disruption.