CVE-2006-3913 in Freeciv
Summary
by MITRE
Buffer overflow in Freeciv 2.1.0-beta1 and earlier, and SVN 15 Jul 2006 and earlier, allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a (1) negative chunk_length or a (2) large chunk->offset value in a PACKET_PLAYER_ATTRIBUTE_CHUNK packet in the generic_handle_player_attribute_chunk function in common/packets.c, and (3) a large packet->length value in the handle_unit_orders function in server/unithand.c.
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Analysis
by VulDB Data Team • 07/08/2019
The vulnerability identified as CVE-2006-3913 represents a critical buffer overflow flaw affecting the Freeciv civilization building game version 2.1.0-beta1 and earlier releases, as well as SVN versions prior to July 15 2006. This security weakness resides within the network protocol handling mechanisms of the game server, specifically in how it processes player attribute chunks and unit order packets. The vulnerability stems from inadequate input validation and bounds checking in the packet processing functions, creating exploitable conditions that can be leveraged by remote attackers to compromise system integrity.
The technical implementation of this vulnerability occurs within the generic_handle_player_attribute_chunk function located in common/packets.c and the handle_unit_orders function found in server/unithand.c. When processing PACKET_PLAYER_ATTRIBUTE_CHUNK packets, the system fails to properly validate the chunk_length parameter which can accept negative values, or the chunk->offset parameter which can contain excessively large values. Additionally, the packet->length parameter in the handle_unit_orders function lacks proper bounds checking, allowing attackers to craft malicious packets that exceed allocated buffer boundaries. These conditions create opportunities for stack-based buffer overflows that can corrupt memory and potentially allow arbitrary code execution.
The operational impact of this vulnerability extends beyond simple denial of service scenarios to include potential remote code execution capabilities. Attackers can exploit these buffer overflows to crash the game server, rendering it unavailable to legitimate users and disrupting multiplayer gaming sessions. The more severe implications arise from the possibility of executing arbitrary code on the target system, which could enable attackers to gain unauthorized access, escalate privileges, or establish persistent backdoors within the gaming environment. This makes the vulnerability particularly dangerous in multiplayer server environments where multiple users connect to a central game server.
The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of inadequate input validation in network protocol handlers. From an ATT&CK framework perspective, this vulnerability maps to T1190 - Exploit Public-Facing Application and T1059 - Command and Scripting Interpreter, as attackers can leverage the overflow to execute malicious code on target systems. The exploit requires minimal privileges since it targets network services accessible to remote users, making it particularly attractive to threat actors seeking to compromise gaming infrastructure. Organizations running Freeciv servers should prioritize immediate patching of affected versions to prevent exploitation and maintain network security posture.
Mitigation strategies include applying the official patches released by the Freeciv development team for versions 2.1.0-beta2 and later, implementing network segmentation to limit exposure of game servers to untrusted networks, and deploying intrusion detection systems to monitor for suspicious packet patterns. Additionally, network administrators should consider implementing input validation at the network level and regularly updating server software to address known vulnerabilities. The vulnerability demonstrates the importance of robust input validation in network protocol implementations and highlights the need for comprehensive security testing of server applications handling external network communications.