CVE-2012-0048 in OpenTTD
Summary
by MITRE
OpenTTD 0.3.5 through 1.1.4 allows remote attackers to cause a denial of service (game pause) by connecting to the server and not finishing the (1) authorization phase or (2) map download, aka a "slow read" attack.
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Analysis
by VulDB Data Team • 12/12/2021
The vulnerability identified as CVE-2012-0048 affects OpenTTD versions 0.3.5 through 1.1.4, representing a significant denial of service weakness that exploits the game server's connection handling mechanisms. This vulnerability operates through a specific class of attack known as slow read or slowloris attacks, where malicious actors establish connections to the game server but deliberately maintain them in incomplete states to consume server resources. The flaw manifests when attackers connect to the server and deliberately fail to complete either the authorization phase or the map download process, creating a resource exhaustion condition that effectively pauses the game for legitimate users.
The technical implementation of this vulnerability stems from inadequate connection state management within the OpenTTD server software. When a client connects to the game server, the system must allocate resources to maintain the connection state while progressing through authentication and map transfer phases. The vulnerability occurs because the server does not implement proper timeouts or resource cleanup mechanisms for connections that remain in transitional states for extended periods. This allows attackers to maintain multiple incomplete connections simultaneously, consuming memory, file descriptors, and processing cycles that should be available for legitimate gameplay operations. The attack specifically targets the protocol handling layer where the server waits for client responses during the authorization and map download stages, creating a window where resources are tied up indefinitely.
From an operational impact perspective, this vulnerability creates a severe disruption to multiplayer gaming experiences by effectively pausing the game server for legitimate players. The slow read attack consumes server resources in a manner that prevents the system from accepting new connections or processing existing ones properly, leading to a cascading failure that affects all players. The attack is particularly insidious because it does not require sophisticated techniques or high privileges to execute, making it accessible to casual attackers who simply need to establish connections and leave them hanging. This vulnerability can be exploited to create sustained service disruption, potentially lasting until the server administrator manually intervenes or the system reaches its resource limits, thereby compromising the availability and integrity of the multiplayer gaming environment.
The vulnerability maps directly to CWE-400, which describes "Uncontrolled Resource Consumption" and aligns with ATT&CK technique T1499.1, "Network Denial of Service" as it specifically targets network resource exhaustion to prevent legitimate service usage. Mitigation strategies should focus on implementing strict connection timeouts, resource monitoring, and connection state management. Server administrators should configure timeout values for authentication phases and map downloads to prevent indefinite hanging connections, while also implementing connection rate limiting to prevent abuse. The fix involves modifying the server code to automatically terminate connections that remain in incomplete states beyond predetermined time limits, ensuring that resources are released promptly and available for legitimate users. Additionally, implementing proper resource accounting and monitoring can help detect such attacks and trigger automated responses to protect the gaming environment from disruption.