CVE-2003-0225 in IIS
Summary
by MITRE
The ASP function Response.AddHeader in Microsoft Internet Information Server (IIS) 4.0 and 5.0 does not limit memory requests when constructing headers, which allow remote attackers to generate a large header to cause a denial of service (memory consumption) with an ASP page.
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Analysis
by VulDB Data Team • 03/08/2021
The vulnerability described in CVE-2003-0225 represents a classic denial of service flaw affecting Microsoft Internet Information Server versions 4.0 and 5.0. This issue specifically targets the Response.AddHeader function within Active Server Pages implementation, creating a condition where malicious actors can exploit memory allocation behavior to exhaust system resources. The flaw exists at the core of how IIS handles HTTP header construction, making it particularly dangerous as it can be triggered through standard web page requests without requiring elevated privileges or complex attack vectors. The vulnerability operates by allowing attackers to craft specially formatted headers that cause the server to allocate excessive memory resources during header processing, ultimately leading to system instability and service disruption.
From a technical perspective, the vulnerability stems from insufficient input validation and memory management within the ASP response handling mechanism. When the Response.AddHeader function processes header data, it fails to implement proper bounds checking or memory allocation limits, allowing attackers to specify header values of arbitrary size. This design flaw creates a memory exhaustion condition where the server allocates increasingly larger amounts of memory to accommodate the oversized header data, eventually consuming all available memory resources. The issue manifests as a denial of service attack that can be executed through simple HTTP requests containing malicious header content, making it particularly dangerous for publicly accessible web servers. The vulnerability is classified under CWE-772, which deals with missing release of memory after effective lifetime, and aligns with ATT&CK technique T1499.004 for network denial of service attacks.
The operational impact of this vulnerability extends beyond simple service disruption to potentially affecting entire web server operations and system availability. When exploited successfully, attackers can cause IIS to consume all available memory resources, leading to complete service unavailability for legitimate users. This type of attack can be particularly devastating in production environments where web servers handle critical business applications, as it can result in significant downtime and potential revenue loss. The vulnerability affects both IIS 4.0 and 5.0 versions, representing a substantial portion of legacy web server deployments that may not have received timely security updates. Organizations running these older server versions face increased risk of exploitation, particularly in environments where patch management processes are delayed or incomplete.
Mitigation strategies for CVE-2003-0225 should focus on both immediate defensive measures and long-term architectural improvements. The most effective immediate solution involves applying Microsoft security patches that address the memory allocation behavior in the Response.AddHeader function, though this requires careful testing to ensure compatibility with existing applications. Organizations should also implement network-level protections such as rate limiting and header size restrictions to prevent exploitation attempts from reaching vulnerable systems. Additionally, deploying intrusion detection systems that can identify unusual header patterns and implementing proper input validation within ASP applications can provide additional layers of defense. The vulnerability highlights the importance of proper resource management and input validation in web server implementations, serving as a reminder of the critical need for secure coding practices in server-side applications. Organizations should also consider migrating away from unsupported IIS versions to receive ongoing security updates and support, as the affected versions are no longer maintained by Microsoft, leaving them vulnerable to additional unpatched security issues.