CVE-2009-1353 in Zervit
Summary
by MITRE
Buffer overflow in the http_parse_hex function in libz/misc.c in Zervit Webserver 0.02 allows remote attackers to cause a denial of service (daemon crash) via a long URI, related to http.c.
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Analysis
by VulDB Data Team • 11/27/2024
The vulnerability identified as CVE-2009-1353 represents a critical buffer overflow flaw within the Zervit Webserver version 0.02 implementation. This security weakness resides in the http_parse_hex function located in the libz/misc.c file, which processes hexadecimal data during HTTP request parsing. The vulnerability specifically manifests when the web server encounters a malformed URI containing an excessively long sequence of characters that exceed the allocated buffer space. This particular implementation flaw demonstrates a classic buffer overflow condition where input validation fails to properly constrain the length of data processed by the http_parse_hex function, creating an exploitable condition that can be leveraged by remote attackers to disrupt service availability.
The technical execution of this vulnerability involves an attacker crafting a malicious HTTP request containing an overly long URI that triggers the buffer overflow during the parsing phase. When the http_parse_hex function processes this malformed input, it attempts to store data beyond the boundaries of its allocated memory buffer in libz/misc.c. This overflow condition corrupts adjacent memory locations and can potentially overwrite critical program execution data such as return addresses or program pointers. The vulnerability directly relates to CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios, making it a significant concern for memory safety in web server implementations. The specific nature of this flaw places it within the ATT&CK framework under the technique T1499.004 for Network Denial of Service, as it enables remote attackers to disrupt service availability through controlled input manipulation.
The operational impact of CVE-2009-1353 extends beyond simple service disruption to potentially compromise the entire web server daemon operation. When exploited successfully, the buffer overflow causes the Zervit Webserver daemon to crash and terminate unexpectedly, resulting in immediate denial of service for all connected clients. This crash condition can be repeatedly triggered by an attacker, leading to sustained service interruption that affects legitimate users and can be used as part of broader attack campaigns targeting web infrastructure availability. The vulnerability affects the core functionality of the web server by compromising its ability to properly parse and handle HTTP requests, creating a persistent point of failure that undermines the server's reliability and availability. The daemon crash represents a complete service outage that requires manual intervention to restore normal operations, making it particularly damaging in production environments where continuous availability is critical.
Mitigation strategies for CVE-2009-1353 require immediate attention through software updates and input validation improvements. The most effective remediation involves upgrading to a patched version of the Zervit Webserver that addresses the buffer overflow condition in the http_parse_hex function. System administrators should implement proper input length validation to prevent excessively long URIs from being processed by the web server, particularly by limiting the maximum URI length that can be handled. Network-level protections such as intrusion detection systems can help detect and block malicious requests attempting to exploit this vulnerability. Additionally, implementing proper memory protection mechanisms including stack canaries and address space layout randomization can provide defense-in-depth against potential exploitation attempts. Organizations should also consider deploying web application firewalls that can filter out malformed HTTP requests before they reach the vulnerable web server component. The vulnerability serves as a reminder of the importance of proper input validation and memory management in web server implementations, highlighting how seemingly simple parsing functions can create critical security weaknesses when not properly secured against adversarial input conditions.