CVE-2002-1705 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer 5.5 through 6.0 allows remote attackers to cause a denial of service (crash) via a Cascading Style Sheet (CSS) with the p{cssText} element declared and a bold font weight.
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Analysis
by VulDB Data Team • 04/20/2025
This vulnerability exists in Microsoft Internet Explorer versions 5.5 through 6.0 and represents a classic buffer overflow condition that manifests through malformed Cascading Style Sheet (CSS) syntax. The flaw specifically occurs when the browser encounters a CSS rule that declares p{cssText} with a bold font weight attribute, causing the application to crash during rendering. The vulnerability stems from inadequate input validation and memory management within the browser's CSS parser, which fails to properly handle the malformed CSS structure that triggers an uncontrolled memory access pattern.
The technical implementation of this vulnerability leverages the browser's handling of CSS properties, particularly when processing elements with specific font weight specifications. When Internet Explorer attempts to render a paragraph element with the cssText property set alongside bold font weight, the parser enters an infinite loop or encounters a memory corruption scenario that results in application termination. This behavior aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-125, which addresses out-of-bounds read errors in memory management. The vulnerability operates at the application layer and requires no special privileges to exploit, making it particularly dangerous as it can be triggered through standard web browsing activities.
From an operational perspective, this vulnerability creates a significant denial of service risk for users of affected Internet Explorer versions, as any web page containing the malicious CSS structure will cause the browser to crash immediately upon loading. Attackers can leverage this weakness by crafting malicious web pages or embedding the problematic CSS in email attachments that, when viewed in the affected browser, will trigger the crash. The impact extends beyond individual user sessions to potentially affect enterprise environments where multiple users may be accessing the same malicious content, creating widespread disruption. This vulnerability also demonstrates the broader category of browser-based exploits that fall under ATT&CK technique T1211, which covers exploitation of memory corruption vulnerabilities in applications.
The mitigation strategies for this vulnerability primarily involve updating to patched versions of Internet Explorer, as Microsoft released security updates specifically addressing this CSS parsing issue. Organizations should also implement web content filtering measures and educate users about avoiding untrusted web content. Browser security policies should include restrictions on CSS processing and memory allocation limits to prevent similar vulnerabilities from causing cascading failures. Additionally, administrators should consider implementing network-level protections that can detect and block known malicious CSS patterns, as the vulnerability's exploitation does not require user interaction beyond normal browsing behavior, making it particularly difficult to defend against without proactive security measures.