CVE-2007-4443 in Unreal engine
Summary
by MITRE
The UCC dedicated server for the Unreal engine, possibly 2003 and 2004, on Windows allows remote attackers to cause a denial of service (continuous beep and server slowdown) via a string containing many 0x07 characters in (1) a request to the images/ directory, (2) the Content-Type field, (3) a HEAD request, and possibly other unspecified vectors.
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Analysis
by VulDB Data Team • 11/02/2017
The vulnerability described in CVE-2007-4443 represents a classic denial of service weakness within the Unreal Engine's UCC dedicated server implementation dating back to 2003 and 2004 versions. This flaw specifically targets the server's handling of malformed input strings containing excessive null byte characters, creating a condition where legitimate server operations become severely degraded or completely halted. The vulnerability operates through multiple attack vectors including requests to the images/ directory, manipulation of the Content-Type field, and even HEAD requests, demonstrating the broad scope of potential exploitation points within the server's input processing mechanisms. The impact manifests as continuous system beeping sounds combined with significant server performance degradation, effectively rendering the service unavailable to legitimate users while consuming substantial system resources.
The technical root cause of this vulnerability aligns with CWE-129, which addresses improper validation of input boundaries, and specifically relates to CWE-400, which covers unchecked resource consumption. The flaw exploits the server's inadequate input sanitization routines that fail to properly handle or limit the occurrence of null characters within various request parameters. When the server encounters strings containing numerous 0x07 characters, its processing logic becomes overwhelmed, leading to resource exhaustion and system instability. The continuous beeping sound indicates the server's internal error handling mechanism being triggered repeatedly, while the server slowdown reflects the computational overhead required to process malformed input. This type of vulnerability falls under the ATT&CK technique T1499.004, specifically targeting network services through resource exhaustion attacks.
The operational impact of this vulnerability extends beyond simple service disruption to encompass potential business continuity issues for organizations relying on Unreal Engine servers for gaming or simulation services. Attackers can exploit this weakness using relatively simple methods requiring minimal technical expertise, making it particularly dangerous in environments where server availability is critical. The vulnerability's persistence across multiple server versions suggests a fundamental flaw in the input processing architecture that was not adequately addressed in subsequent releases. Organizations using affected Unreal Engine versions face significant risk of service interruption, particularly in competitive gaming environments where server uptime directly impacts user experience and business revenue. The vulnerability's susceptibility to various attack vectors including directory requests, header manipulation, and HTTP method variations increases the difficulty of comprehensive protection.
Mitigation strategies for CVE-2007-4443 should focus on implementing robust input validation mechanisms that enforce strict character limit thresholds for all incoming request parameters, particularly within the images/ directory access points and Content-Type field handling. System administrators should deploy network-level filters that can detect and block malformed requests containing excessive null characters before they reach the server processing layer. The implementation of rate limiting and connection throttling mechanisms can help prevent exploitation attempts from consuming excessive resources. Additionally, organizations should consider applying the latest available patches from Epic Games, though given the age of this vulnerability, such updates may not be available for the affected versions. Network segmentation and intrusion detection systems should be configured to monitor for unusual patterns of requests containing null character sequences. Regular security audits of server configurations and input handling routines are essential to prevent similar vulnerabilities from emerging in newer implementations. The vulnerability serves as a reminder of the importance of proper input validation in server applications and the potential for seemingly minor flaws to create significant operational disruptions.