CVE-2003-0218 in HTTP Daemon
Summary
by MITRE
Buffer overflow in PostMethod() function for Monkey HTTP Daemon (monkeyd) 0.6.1 and earlier allows remote attackers to execute arbitrary code via a POST request with a large body.
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Analysis
by VulDB Data Team • 08/23/2025
The vulnerability identified as CVE-2003-0218 represents a critical buffer overflow condition within the Monkey HTTP Daemon version 0.6.1 and earlier releases. This flaw exists specifically within the PostMethod() function, which handles HTTP POST requests processed by the web server. The vulnerability arises from inadequate input validation and bounds checking when processing POST request bodies, creating an exploitable condition that can be leveraged by remote attackers to gain unauthorized system access. The flaw fundamentally stems from the daemon's failure to properly validate the size of incoming data before attempting to store it in fixed-size memory buffers, a classic software security weakness that has been documented in numerous security frameworks including CWE-121. The vulnerability affects the core functionality of the web server by allowing malicious actors to overflow memory buffers and potentially overwrite adjacent memory regions, including return addresses and control data structures.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it enables remote code execution capabilities that can result in complete system compromise. When a remote attacker crafts a POST request containing an oversized payload, the vulnerable PostMethod() function fails to properly handle the excessive data, leading to memory corruption that can be exploited to redirect program execution flow. This type of vulnerability aligns with ATT&CK technique T1190, which describes the exploitation of vulnerabilities in web applications to execute arbitrary code. The attack vector is particularly concerning because it requires no authentication or privileged access, making it an attractive target for automated exploitation tools. The vulnerability can be exploited across network boundaries, allowing attackers to execute malicious code with the privileges of the web server process, which typically runs with system-level permissions on many deployments. The memory corruption pattern associated with this buffer overflow can be manipulated to inject and execute shellcode, potentially leading to complete system takeover.
Mitigation strategies for CVE-2003-0218 must address both immediate remediation and long-term architectural improvements to prevent similar vulnerabilities from occurring. The primary and most effective mitigation is the immediate upgrade to Monkey HTTP Daemon version 0.6.2 or later, which contains the necessary patches to address the buffer overflow condition. Organizations should also implement network-level protections such as intrusion detection systems that can identify and block suspicious POST request patterns, particularly those with unusually large payloads that exceed normal application behavior. Input validation controls should be strengthened at multiple layers including application firewalls, web application firewalls, and proxy servers to filter out potentially malicious requests before they reach the vulnerable daemon. Security monitoring should include logging and alerting on large POST requests, as this behavior can serve as an indicator of exploitation attempts. Additionally, implementing proper memory protection mechanisms such as stack canaries, address space layout randomization, and non-executable stack protections can provide defense-in-depth measures that would make exploitation more difficult even if the underlying vulnerability remains unpatched. Organizations should also conduct thorough security assessments of their web server configurations and implement principle of least privilege for web server processes to minimize potential damage from successful exploitation attempts.