CVE-2009-3663 in httpdx
Summary
by MITRE
Format string vulnerability in the h_readrequest function in http.c in httpdx Web Server 1.4 allows remote attackers to cause a denial of service (crash) or execute arbitrary code via format string specifiers in the Host header.
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Analysis
by VulDB Data Team • 12/14/2024
The CVE-2009-3663 vulnerability represents a critical format string flaw in the httpdx Web Server version 1.4 that exposes remote attackers to significant security risks. This vulnerability specifically resides within the h_readrequest function in the http.c module, where improper input validation allows malicious actors to manipulate format string specifiers through the Host header parameter. The flaw demonstrates characteristics consistent with CWE-134, which categorizes format string vulnerabilities as weaknesses that occur when a program uses a user-supplied string as a format string without proper sanitization. The httpdx Web Server's failure to properly handle format string arguments in the Host header creates an exploitable condition that can be leveraged for both denial of service and arbitrary code execution attacks.
The technical exploitation of this vulnerability occurs when a remote attacker crafts a malicious Host header containing format specifiers such as %x, %s, or %n that are then processed by the vulnerable h_readrequest function. When the web server attempts to process these malformed format specifiers, the application's memory management becomes corrupted, leading to unpredictable behavior. The attacker can manipulate the stack pointer and memory contents through these format specifiers, potentially causing the application to crash or allowing execution of arbitrary code with the privileges of the web server process. This vulnerability directly maps to ATT&CK technique T1203, which involves exploiting software vulnerabilities to gain remote code execution capabilities.
The operational impact of CVE-2009-3663 extends beyond simple service disruption to encompass potential system compromise and data exposure. A successful exploit can result in complete system takeover, allowing attackers to establish persistent access, escalate privileges, or exfiltrate sensitive information from the affected server. The vulnerability's remote nature means that attackers do not require local access or authentication to exploit the flaw, making it particularly dangerous in publicly accessible web server environments. Organizations running httpdx Web Server 1.4 are at significant risk of compromise, as the vulnerability can be exploited through simple HTTP requests without requiring complex attack chains or specialized tools. The denial of service component of this vulnerability can be used for distributed denial of service attacks, where multiple attackers can simultaneously crash the web server and render services unavailable to legitimate users.
Mitigation strategies for CVE-2009-3663 should prioritize immediate patching of the affected httpdx Web Server version 1.4 to address the underlying format string vulnerability. Organizations should implement network-level restrictions to limit access to the web server and monitor for suspicious Host header patterns that may indicate exploitation attempts. Input validation measures should be strengthened to sanitize all user-supplied data, particularly headers, before processing. The implementation of proper format string handling practices, such as using fixed string formats instead of user-controlled format specifiers, provides defense-in-depth protection against similar vulnerabilities. Additionally, regular security assessments and vulnerability scanning should be conducted to identify and remediate other potential weaknesses in web server configurations. Organizations should also consider deploying intrusion detection systems to monitor for exploitation attempts and maintain up-to-date security patches for all web server components to prevent similar vulnerabilities from being exploited in the future.