CVE-2001-1450 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer 5.0 through 6.0 allows attackers to cause a denial of service (browser crash) via a crafted FTP URL such as "/.#./".
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Analysis
by VulDB Data Team • 11/17/2024
This vulnerability exists in Microsoft Internet Explorer versions 5.0 through 6.0 and represents a classic buffer overflow condition that can be exploited to trigger a denial of service attack. The flaw specifically manifests when the browser encounters a malformed FTP URL containing the sequence "/.#./" which causes the application to crash during URL parsing operations. The vulnerability stems from inadequate input validation within the browser's FTP protocol handler, where the application fails to properly sanitize and validate the path components of FTP URLs before processing them. This issue falls under the CWE-121 category of Stack-based Buffer Overflow, where the application writes beyond the bounds of allocated memory buffers during the parsing of maliciously crafted URLs. The attack vector is particularly insidious because it can be delivered through web pages or email attachments containing maliciously crafted links that users might inadvertently click. When a user navigates to such a URL, the browser's FTP handler attempts to process the malformed path component and overflows the allocated buffer, leading to an immediate application crash and complete browser termination. This vulnerability directly impacts the availability of the browser service and can be classified under the MITRE ATT&CK technique T1499.004 for Network Denial of Service, where an attacker can disrupt service availability by causing application instability. The exploitation requires minimal technical skill and can be automated through web-based attack vectors, making it particularly dangerous in environments where users frequently access untrusted web content. The vulnerability demonstrates a critical flaw in Microsoft's input validation practices and highlights the importance of proper boundary checking in protocol handlers. Organizations using affected versions of Internet Explorer should consider immediate mitigation strategies including browser updates, network-based filtering of suspicious URLs, and user education about avoiding potentially malicious links. The issue also underscores the broader security principle that applications must never trust input from external sources without proper validation and sanitization, as highlighted in the OWASP Top Ten security risks. Microsoft addressed this vulnerability through security updates that improved URL parsing and input validation within the FTP protocol handler, emphasizing the importance of regular security patching for maintaining application stability and security. The vulnerability serves as a reminder of how seemingly innocuous URL components can be exploited to cause significant service disruption and highlights the need for comprehensive testing of protocol handlers against malformed inputs. This particular flaw exemplifies the challenges faced by browser vendors in maintaining security while supporting legacy protocols and demonstrates how buffer overflows in web browsers can be leveraged for denial of service attacks that impact user productivity and system availability. The incident also reinforces the necessity of implementing defense-in-depth strategies that include network monitoring, intrusion detection systems, and application-level security controls to protect against such exploitation vectors.