CVE-2001-0322 in Internet Explorer
Summary
by MITRE
MSHTML.DLL HTML parser in Internet Explorer 4.0, and other versions, allows remote attackers to cause a denial of service (application crash) via a script that creates and deletes an object that is associated with the browser window object.
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Analysis
by VulDB Data Team • 01/29/2025
The vulnerability described in CVE-2001-0322 represents a classic heap corruption issue within the MSHTML.DLL component of Internet Explorer 4.0 and subsequent versions. This flaw resides in the HTML parser's handling of dynamic object manipulation within the browser's scripting environment, specifically when scripts attempt to create and immediately delete objects that maintain references to the browser window object. The vulnerability operates through a race condition or memory management error that occurs during the object lifecycle management process, where the parser fails to properly handle the cleanup sequence of dynamically allocated memory structures associated with window object references.
The technical implementation of this vulnerability exploits the interaction between JavaScript execution and the underlying MSHTML rendering engine's memory management subsystem. When a malicious script creates an object that maintains a reference to the browser window context and subsequently deletes it, the MSHTML.DLL parser encounters a scenario where memory deallocation occurs while the object is still in use or in an inconsistent state. This condition triggers an invalid memory access or buffer overflow within the parser's internal data structures, leading to an application crash that manifests as a denial of service. The vulnerability is particularly dangerous because it can be triggered through standard web content without requiring special privileges or complex exploitation techniques.
The operational impact of CVE-2001-0322 extends beyond simple service disruption to potentially enable more sophisticated attacks within the context of a compromised browser session. While the immediate effect is a denial of service that causes Internet Explorer to crash and restart, this vulnerability creates opportunities for attackers to exploit the unstable state of the browser process. The flaw can be leveraged in conjunction with other vulnerabilities to achieve arbitrary code execution, as demonstrated by the broader ATT&CK framework's categorization of such memory corruption issues under the 'Exploitation for Client Execution' tactic. From a compliance perspective, this vulnerability violates security standards such as those outlined in CWE-125, which addresses out-of-bounds read conditions, and CWE-129, which covers improper validation of array indices, both of which are relevant to the memory management failures present in the MSHTML parser.
Mitigation strategies for this vulnerability require both immediate remediation and long-term architectural improvements to browser security. Organizations should implement the official Microsoft security patches that address the memory management issues in MSHTML.DLL, while also considering browser hardening techniques such as sandboxing and privilege separation. The vulnerability highlights the importance of proper input validation and memory management in browser components, aligning with industry best practices for secure coding as outlined in the OWASP Top Ten and NIST Cybersecurity Framework. Additionally, network-level protections such as web application firewalls and content filtering systems can help prevent exploitation by blocking malicious scripts before they reach vulnerable browser versions, though these measures are secondary to proper patch management and system hardening. The remediation process should also include comprehensive testing to ensure that the patch does not introduce compatibility issues with existing web applications that may rely on the problematic behavior, while also implementing monitoring to detect potential exploitation attempts through anomalous browser crash patterns or memory access violations.