CVE-2001-0720 in Internet Explorer
Summary
by MITRE
Internet Explorer 5.1 for Macintosh on Mac OS X allows remote attackers to execute arbitrary commands by causing a BinHex or MacBinary file type to be downloaded, which causes the files to be executed if automatic decoding is enabled.
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Analysis
by VulDB Data Team • 04/07/2017
This vulnerability resides in the Internet Explorer 5.1 for Macintosh browser running on Mac OS X systems, representing a critical remote code execution flaw that exploits the browser's handling of specific file types. The vulnerability specifically targets the automatic decoding feature that processes BinHex and MacBinary encoded files, which are common file formats used in macintosh environments for encoding binary data during transmission. When a user visits a malicious website that serves these encoded files, the browser automatically attempts to decode and execute them without proper validation or user confirmation, creating an exploitable condition that allows remote attackers to execute arbitrary commands on the target system.
The technical flaw stems from improper input validation and insufficient sandboxing mechanisms within the browser's file handling subsystem. When Internet Explorer encounters a BinHex or MacBinary file during web browsing, it automatically processes these files using built-in decoding routines that lack proper security boundaries. This behavior violates fundamental security principles by executing potentially malicious code without user interaction or explicit consent, effectively bypassing traditional security controls. The vulnerability operates at the application level where the browser's file interpretation logic fails to distinguish between legitimate and malicious encoded content, creating a privilege escalation path that can lead to complete system compromise.
The operational impact of this vulnerability is severe as it enables attackers to gain arbitrary code execution capabilities on affected systems without requiring any user interaction beyond visiting a malicious website. Once executed, the malicious code can perform any action that the user account has permissions to perform, including installing malware, modifying system files, accessing sensitive data, or establishing persistent backdoors. The vulnerability is particularly dangerous because it leverages the browser's legitimate functionality to execute malicious code, making it difficult to detect through traditional network monitoring or endpoint protection mechanisms. This creates a stealthy attack vector that can remain undetected while providing attackers with complete control over the compromised system.
The vulnerability maps directly to CWE-74 and CWE-94 within the Common Weakness Enumeration framework, specifically addressing weaknesses in external control of system or process and improper validation of a file name or path. From an ATT&CK framework perspective, this vulnerability enables techniques such as T1059.007 for command and scripting interpreter and T1068 for exploit for privilege escalation. The attack surface is further expanded by the fact that this vulnerability affects a widely deployed browser on a popular operating system platform, making it a high-value target for automated exploitation campaigns. Organizations should implement immediate mitigations including disabling automatic file decoding features, updating to patched versions of the browser, and implementing network-level controls to block access to known malicious domains. Additionally, user education regarding the dangers of visiting untrusted websites and the importance of keeping software updated remains crucial in defending against such exploitation attempts.