CVE-2006-3657 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer 6 allows remote attackers to cause a denial of service (stack overflow exception) via a DXImageTransform.Microsoft.Gradient ActiveX object with a long (1) StartColorStr or (2) EndColorStr property.
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Analysis
by VulDB Data Team • 05/07/2019
Microsoft Internet Explorer 6 vulnerable to stack overflow exploitation through DXImageTransform.Microsoft.Gradient ActiveX object manipulation represents a critical buffer overflow vulnerability that demonstrates the inherent risks of ActiveX component handling in web browsers. This vulnerability specifically targets the parsing mechanism of gradient color properties within the ActiveX control, creating an exploitable condition when malformed input data exceeds allocated memory buffers. The flaw exists in the way IE processes the StartColorStr and EndColorStr parameters, which are designed to define color gradients in visual elements, but the implementation fails to properly validate input length constraints.
The technical execution of this vulnerability involves crafting malicious HTML content that includes the DXImageTransform.Microsoft.Gradient ActiveX object with intentionally extended color string parameters. When the browser attempts to render this content, the excessive string length causes the stack memory allocation to overflow, resulting in an unhandled exception that terminates the browser process. This behavior aligns with CWE-121, heap-based buffer overflow conditions, and demonstrates how improper input validation can lead to denial of service scenarios. The attack vector operates through web content delivery where users unknowingly trigger the vulnerable code path during page rendering, making it particularly dangerous in phishing campaigns or malicious websites.
The operational impact of this vulnerability extends beyond simple service disruption to encompass potential system compromise and user experience degradation. When exploited successfully, the stack overflow causes Internet Explorer to crash, effectively denying users access to web content and potentially providing attackers with a foothold for more sophisticated attacks. The vulnerability's exploitation requires minimal user interaction beyond visiting a malicious webpage, making it particularly effective in social engineering campaigns. Security professionals should note that this vulnerability affects legacy systems where users may not have updated to newer browser versions, creating persistent attack surfaces that require immediate remediation.
Mitigation strategies for this vulnerability should focus on both immediate defensive measures and long-term architectural improvements. Organizations must implement browser security policies that disable ActiveX controls or restrict their execution to trusted domains, as recommended by the ATT&CK framework's T1175 technique for application sandboxing. Patch management becomes critical as Microsoft released updates to address this specific vulnerability, but many systems remain unpatched due to legacy dependencies. Network-level protections such as web application firewalls can help detect and block malicious content attempting to exploit this specific ActiveX object manipulation pattern. Additionally, user education regarding suspicious website content and the importance of keeping browsers updated remains essential in reducing exploitation success rates.