CVE-2009-2629 in nginx
Summary
by MITRE
Buffer underflow in src/http/ngx_http_parse.c in nginx 0.1.0 through 0.5.37, 0.6.x before 0.6.39, 0.7.x before 0.7.62, and 0.8.x before 0.8.15 allows remote attackers to execute arbitrary code via crafted HTTP requests.
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Analysis
by VulDB Data Team • 12/21/2024
The vulnerability identified as CVE-2009-2629 represents a critical buffer underflow condition within the nginx web server software that existed across multiple version ranges from 0.1.0 through 0.5.37, 0.6.x versions before 0.6.39, 0.7.x versions before 0.7.62, and 0.8.x versions before 0.8.15. This flaw resides in the http parsing component located at src/http/ngx_http_parse.c, making it a fundamental security issue that affects the core functionality of the web server. The buffer underflow condition occurs when processing specially crafted HTTP requests, creating a scenario where an attacker can manipulate memory operations to achieve unauthorized code execution.
The technical implementation of this vulnerability stems from inadequate bounds checking within the HTTP request parsing logic. When nginx processes incoming HTTP requests, it attempts to parse various header fields and request components without sufficient validation of buffer boundaries. This specific underflow condition allows attackers to provide malformed HTTP requests that cause the application to write data beyond the allocated memory buffer, potentially overwriting adjacent memory locations. The flaw operates at the protocol parsing layer, making it particularly dangerous as it can be exploited through standard HTTP traffic without requiring special privileges or authentication. According to CWE-129, this vulnerability maps directly to improper input validation, specifically related to insufficient bounds checking during buffer operations.
The operational impact of CVE-2009-2629 is severe and encompasses complete system compromise potential. Remote attackers can leverage this vulnerability to execute arbitrary code on affected systems, effectively gaining full control over the web server instance. This capability enables attackers to establish persistent backdoors, escalate privileges, or launch further attacks against internal network resources. The vulnerability affects organizations running any of the affected nginx versions, creating widespread exposure across internet-facing web servers. The exploitation requires only the ability to send HTTP requests to the target server, making it highly accessible and dangerous for organizations with exposed web services. This vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as successful exploitation would allow attackers to execute commands on the compromised system.
Mitigation strategies for CVE-2009-2629 require immediate action to upgrade affected nginx installations to patched versions. Organizations should prioritize updating to nginx versions 0.5.38, 0.6.39, 0.7.62, or 0.8.15 respectively, which contain the necessary fixes for the buffer underflow condition. Network administrators should implement additional protective measures including web application firewalls, intrusion detection systems, and rate limiting to detect and prevent exploitation attempts. The vulnerability demonstrates the critical importance of maintaining current software versions and implementing robust input validation mechanisms. Security teams should conduct thorough vulnerability assessments to identify all systems running affected nginx versions and establish monitoring procedures to detect potential exploitation attempts. The remediation process should include comprehensive testing of updated configurations to ensure service availability while eliminating the security risk.