CVE-2007-1946 in Windows
Summary
by MITRE
Integer overflow in Windows Explorer in Microsoft Windows XP SP1 might allow user-assisted remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a large width dimension in a crafted BMP image, as demonstrated by w4intof.bmp.
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Analysis
by VulDB Data Team • 06/08/2025
The vulnerability described in CVE-2007-1946 represents a critical integer overflow flaw within Windows Explorer's handling of bitmap image files on Microsoft Windows XP Service Pack 1 systems. This issue specifically manifests when the operating system attempts to process a crafted BMP image file containing an excessively large width dimension that exceeds the maximum value an integer can represent. The vulnerability falls under the CWE-190 category of integer overflow, where the system fails to properly validate input parameters before performing arithmetic operations that could result in unexpected behavior.
The technical execution of this vulnerability occurs through the manipulation of BMP file headers, particularly the width field that defines the horizontal dimension of the image. When Windows Explorer attempts to parse a maliciously crafted BMP file such as w4intof.bmp, it interprets the oversized width value as an integer that eventually overflows, causing the application to behave unpredictably. This overflow condition can trigger memory corruption within the image processing routines, leading to application instability and potential code execution. The vulnerability requires user interaction to be exploited effectively, as the attacker must convince a victim to open the malicious image file through Windows Explorer, making it a user-assisted remote attack vector.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable arbitrary code execution on affected systems. When the integer overflow occurs during image processing, it can corrupt memory structures and overwrite critical program data, creating opportunities for attackers to inject and execute malicious code within the context of the Windows Explorer process. This represents a significant security risk for Windows XP users, as the vulnerability could be exploited to gain unauthorized access to systems or escalate privileges. The attack surface is particularly concerning given that Windows Explorer was frequently used for opening various file types, making the exploitation vector quite broad and accessible.
Mitigation strategies for CVE-2007-1946 should focus on both immediate defensive measures and long-term system hardening approaches. Microsoft addressed this vulnerability through security updates that included enhanced input validation for BMP file processing and improved bounds checking mechanisms. System administrators should ensure that all Windows XP systems are updated with the latest security patches, particularly the cumulative security update that specifically addresses this vulnerability. Additional protective measures include implementing strict file type validation for image files, disabling automatic image preview in file explorer where possible, and employing network-level filtering to prevent the delivery of potentially malicious image files. Organizations should also consider implementing application whitelisting policies to restrict the execution of unauthorized image processing applications that might be vulnerable to similar integer overflow conditions. The vulnerability demonstrates the importance of proper input validation and memory management in preventing exploitation of integer overflow conditions, aligning with ATT&CK technique T1059 for execution through application layer protocols and T1203 for exploitation of system vulnerabilities.