CVE-2010-1098 in Windows
Summary
by MITRE
The ANI parser in Microsoft Windows before 7 on the x86 platform, as used in Internet Explorer and other applications, allows remote attackers to cause a denial of service (memory and CPU consumption) via a crafted biClrUsed value in the BITMAPINFO header of a .ANI file.
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Analysis
by VulDB Data Team • 05/03/2026
The vulnerability described in CVE-2010-1098 represents a critical denial of service weakness in Microsoft Windows operating systems prior to version 7, specifically affecting the ANI file parser component. This flaw exists within the Windows x86 platform implementation and impacts Internet Explorer and other applications that utilize the ANI file format parsing capabilities. The vulnerability stems from insufficient input validation within the BITMAPINFO header structure, particularly concerning the biClrUsed field which specifies the number of color indexes in the color table used for the bitmap.
The technical implementation of this vulnerability exploits the ANI file format parsing mechanism where the biClrUsed value is manipulated to trigger excessive memory allocation and CPU consumption patterns. When a maliciously crafted ANI file is processed, the parser fails to properly validate the biClrUsed field, allowing an attacker to specify an abnormally large value that causes the system to allocate excessive memory resources. This malformed value triggers a memory allocation loop or excessive processing cycles within the ANI parser, leading to significant resource exhaustion that ultimately results in system instability and denial of service conditions.
From an operational perspective, this vulnerability presents a significant risk to Windows users running affected versions, as it can be exploited through web-based attacks or malicious file downloads. The attack vector requires minimal user interaction, making it particularly dangerous in phishing campaigns or compromised websites where users might unknowingly trigger the malicious ANI file processing. The impact extends beyond simple service disruption to potentially affect system performance and availability, as the excessive memory and CPU consumption can render systems unresponsive or cause applications to crash repeatedly.
This vulnerability maps to CWE-129 Input Validation and OWASP Top Ten category A03: Injection, specifically targeting improper input validation mechanisms within Windows system components. The attack pattern aligns with techniques documented in the MITRE ATT&CK framework under T1499.004 Network Denial of Service and T1059 Command and Scripting Interpreter, as it leverages system parsing mechanisms to consume resources. Microsoft addressed this vulnerability through security updates that implemented proper bounds checking and input validation for the biClrUsed field within ANI file processing, requiring users to apply the relevant security patches to remediate the issue.
The broader implications of this vulnerability highlight the importance of robust input validation in system components that handle file format parsing operations. It demonstrates how seemingly minor flaws in parser implementations can result in significant denial of service conditions, particularly when dealing with multimedia file formats that require complex parsing routines. Organizations should ensure comprehensive patch management programs are in place to address such vulnerabilities promptly, as the attack surface remains relevant for legacy systems that have not been properly updated or migrated to supported Windows versions.