CVE-2011-3192 in Secure Backup
Summary
by MITRE
The byterange filter in the Apache HTTP Server 1.3.x, 2.0.x through 2.0.64, and 2.2.x through 2.2.19 allows remote attackers to cause a denial of service (memory and CPU consumption) via a Range header that expresses multiple overlapping ranges, as exploited in the wild in August 2011, a different vulnerability than CVE-2007-0086.
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Analysis
by VulDB Data Team • 01/27/2025
The CVE-2011-3192 vulnerability represents a critical denial of service flaw affecting Apache HTTP Server versions spanning 1.3.x through 2.0.64 and 2.2.x through 2.2.19. This vulnerability specifically targets the byterange filter component within the server's handling of HTTP Range requests, which is designed to allow clients to request specific portions of a resource rather than the entire file. The flaw manifests when a malicious client submits a Range header containing multiple overlapping byte ranges, creating an exploitable condition that can be leveraged to consume excessive system resources and ultimately cause service disruption.
The technical mechanism behind this vulnerability involves the server's inefficient processing of overlapping byte ranges within the byterange filter. When Apache receives a Range header with multiple overlapping segments, the internal parsing and validation logic fails to properly handle the overlap conditions, leading to exponential resource consumption during request processing. This occurs because the server's implementation does not adequately optimize or consolidate overlapping ranges before processing, causing it to perform redundant calculations and memory allocations. The vulnerability falls under CWE-129, which describes improper validation of the length of a buffer, and more specifically relates to CWE-400, indicating an unchecked resource consumption issue that allows for denial of service through excessive resource allocation.
The operational impact of this vulnerability extends beyond simple service disruption to encompass significant performance degradation and system instability. Attackers can exploit this weakness by crafting specially formatted Range headers that trigger the server's inefficient processing logic, causing memory consumption to spike dramatically while CPU usage reaches near 100% utilization. This resource exhaustion effectively renders the affected Apache servers unavailable to legitimate users, making it particularly dangerous in production environments where service availability is critical. The vulnerability was actively exploited in the wild during August 2011, demonstrating its real-world threat level and the importance of immediate remediation. The attack vector aligns with ATT&CK technique T1499.004, which describes the use of resource exhaustion to cause denial of service, and represents a sophisticated approach to system compromise through indirect resource manipulation rather than direct exploitation.
Mitigation strategies for CVE-2011-3192 require immediate implementation of patches and updates to affected Apache server versions, with the most effective solution being the upgrade to patched versions that properly handle overlapping byte ranges in Range headers. Organizations should also consider implementing rate limiting and request validation mechanisms at network boundaries to detect and block malformed Range headers before they reach the vulnerable server. Additionally, monitoring systems should be configured to alert on unusual memory and CPU consumption patterns that may indicate exploitation attempts. The vulnerability highlights the importance of proper input validation and resource management in web server implementations, as outlined in security best practices such as those referenced in OWASP Top Ten and NIST cybersecurity guidelines. Network administrators should also implement defensive measures including firewall rules that limit Range header complexity and consider deploying web application firewalls that can identify and block suspicious HTTP request patterns associated with this specific exploit technique.