CVE-2002-0079 in IIS
Summary
by MITRE
Buffer overflow in the chunked encoding transfer mechanism in Internet Information Server (IIS) 4.0 and 5.0 Active Server Pages allows attackers to cause a denial of service or execute arbitrary code.
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Analysis
by VulDB Data Team • 09/23/2025
The vulnerability described in CVE-2002-0079 represents a critical buffer overflow condition within the chunked encoding transfer mechanism of Microsoft Internet Information Server versions 4.0 and 5.0. This flaw specifically affects Active Server Pages functionality and demonstrates a classic example of improper input validation in web server implementations. The issue arises when IIS processes HTTP requests containing malformed chunked encoding data, creating an opportunity for malicious actors to exploit memory handling weaknesses in the server's processing pipeline.
The technical implementation of this vulnerability stems from inadequate bounds checking during the parsing of chunked transfer encoding data streams. When IIS receives HTTP requests with chunked encoding, it must process the data in segments and reconstruct the complete payload for further processing. The buffer overflow occurs when the server fails to properly validate the length specifications within chunked encoding headers, allowing attackers to provide oversized chunk size indicators that exceed the allocated buffer space. This fundamental flaw in memory management creates opportunities for both denial of service conditions and arbitrary code execution, as the overflow can overwrite adjacent memory locations including return addresses and program control structures.
The operational impact of CVE-2002-0079 extends beyond simple service disruption to encompass potential system compromise and unauthorized access. Attackers exploiting this vulnerability can cause IIS servers to crash and restart repeatedly, leading to denial of service conditions that affect legitimate users and business operations. More critically, the buffer overflow can be leveraged to execute arbitrary code with the privileges of the IIS service account, potentially allowing attackers to gain complete control over affected systems. This vulnerability particularly affects organizations running legacy IIS versions where patch management may be delayed or incomplete, making the attack surface more extensive than initially apparent.
Security professionals should consider this vulnerability in the context of broader web application security frameworks and threat modeling practices. The flaw aligns with CWE-121, which describes stack-based buffer overflow conditions, and demonstrates how improper input validation can lead to severe consequences in web server environments. From an ATT&CK framework perspective, this vulnerability maps to techniques involving remote code execution and privilege escalation, with potential for lateral movement within compromised networks. Organizations should implement immediate mitigations including applying Microsoft security patches, disabling chunked encoding processing where possible, and implementing network-based protections such as intrusion detection systems to monitor for exploitation attempts. The vulnerability also underscores the importance of maintaining current security practices and regular vulnerability assessments to identify and remediate similar weaknesses in legacy systems.