CVE-2006-3943 in Internet Explorer
Summary
by MITRE
Stack-based buffer overflow in NDFXArtEffects in Microsoft Internet Explorer 6 on Windows XP SP2 allows remote attackers to cause a denial of service (crash) via long (1) RGBExtraColor, (2) RGBForeColor, and (3) RGBBackColor properties.
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Analysis
by VulDB Data Team • 05/07/2019
The vulnerability identified as CVE-2006-3943 represents a critical stack-based buffer overflow flaw within the NDFXArtEffects component of Microsoft Internet Explorer 6 running on Windows XP Service Pack 2 systems. This vulnerability specifically targets three distinct properties within the affected component: RGBExtraColor, RGBForeColor, and RGBBackColor, all of which accept excessively long input values that exceed the allocated stack buffer space. The flaw stems from inadequate input validation and bounds checking within the processing of these color properties, creating a condition where maliciously crafted input can overwrite adjacent stack memory locations.
The technical implementation of this vulnerability exploits the fundamental principle of stack memory management in Windows applications, where local variables and function return addresses are stored in a contiguous memory region. When the NDFXArtEffects component processes the RGB color properties, it fails to properly validate the length of input data before copying it into fixed-size stack buffers. This oversight allows attackers to supply input data that exceeds the buffer capacity, resulting in memory corruption that can overwrite critical stack metadata including return addresses and saved registers. The vulnerability manifests as a crash or denial of service condition, effectively rendering the affected browser instance unstable and unresponsive.
From an operational perspective, this vulnerability presents significant risk to users of Internet Explorer 6 on Windows XP SP2 systems, as it can be exploited through web-based attacks without requiring user interaction beyond visiting a malicious website. The attack vector leverages the browser's handling of rich media content and visual effects, making it particularly dangerous in environments where users encounter untrusted web content regularly. The impact extends beyond simple browser crashes, as successful exploitation could potentially enable more sophisticated attacks if combined with other vulnerabilities or if the memory corruption leads to executable code injection. This vulnerability directly maps to CWE-121 Stack-based Buffer Overflow, which is categorized under the broader weakness of insufficient input validation and represents a classic example of memory safety issues in legacy software implementations.
The exploitation of this vulnerability aligns with several tactics outlined in the MITRE ATT&CK framework, particularly those related to initial access through malicious web content and privilege escalation through application exploitation. The attack requires no special privileges or user interaction beyond normal browsing behavior, making it particularly dangerous in enterprise environments where users may encounter untrusted web content. Organizations running vulnerable systems face significant exposure as this vulnerability affects widely deployed software components and lacks effective client-side mitigations. The vulnerability's impact is further amplified by the fact that Windows XP SP2 was a widely used operating system at the time of discovery, creating a large attack surface for threat actors.
Mitigation strategies for CVE-2006-3943 should prioritize immediate patch deployment through Microsoft's security updates, as the vendor provided specific fixes for this vulnerability. System administrators should implement network-based protections including web content filtering and intrusion prevention systems to block access to malicious web content that may exploit this vulnerability. Additionally, users should be educated about the risks of visiting untrusted websites and the importance of keeping software updated. The vulnerability highlights the critical importance of proper input validation and memory management in software development practices, particularly for legacy applications that may not have undergone modern security review processes. Organizations should also consider implementing application whitelisting policies and restricting access to potentially vulnerable components through browser security settings to reduce the attack surface available to threat actors.