CVE-2001-0150 in Internet Explorer
Summary
by MITRE
Internet Explorer 5.5 and earlier executes Telnet sessions using command line arguments that are specified by the web site, which could allow remote attackers to execute arbitrary commands if the IE client is using the Telnet client provided in Services for Unix (SFU) 2.0, which creates session transcripts.
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Analysis
by VulDB Data Team • 03/24/2025
This vulnerability exists in Internet Explorer versions 5.5 and earlier where the browser fails to properly validate command line arguments passed from web pages to the Telnet client. When a user visits a malicious website that attempts to initiate a Telnet session, the browser can pass arbitrary command line parameters to the underlying Telnet client. This flaw is specifically exploitable when the Internet Explorer client is configured to use the Telnet client provided in Services for Unix 2.0, which creates session transcripts that can be manipulated by attackers. The vulnerability stems from insufficient input validation and sanitization of user-supplied data that flows from web content into system-level commands, creating a path for privilege escalation and remote code execution.
The technical implementation of this vulnerability relies on the improper handling of command line parameters within the Internet Explorer browser architecture. When a web page attempts to establish a Telnet connection, the browser constructs command line arguments that are passed directly to the Telnet executable without adequate sanitization. This represents a classic command injection vulnerability where untrusted input is incorporated into system commands without proper validation or escaping mechanisms. The vulnerability is categorized under CWE-78 as "Improper Neutralization of Special Elements used in an OS Command" and aligns with ATT&CK technique T1059.007 for "Command and Scripting Interpreter: Unix Shell" where adversaries leverage command injection to execute arbitrary code on compromised systems.
The operational impact of this vulnerability is significant as it allows remote attackers to execute arbitrary commands on vulnerable systems with the privileges of the user running Internet Explorer. Since the Telnet client in Services for Unix 2.0 creates session transcripts, attackers can potentially manipulate these files to achieve persistence or escalate privileges. The vulnerability affects systems where SFU 2.0 is installed and where Internet Explorer is configured to handle Telnet URLs, creating a dangerous attack surface that can be exploited from remote locations. This represents a critical security flaw in the browser's handling of external protocol handlers and demonstrates the risks associated with inadequate input validation in web browsers.
Mitigation strategies for this vulnerability include immediate patching of Internet Explorer to versions that properly validate command line arguments, disabling Telnet protocol handling in the browser configuration, and implementing network-level controls to restrict access to Telnet services. Organizations should also consider disabling the Services for Unix Telnet client if it is not essential for business operations. The recommended approach involves implementing proper input validation and sanitization at multiple layers, including browser protocol handlers and system command execution interfaces. Additionally, network segmentation and firewall rules should be configured to prevent unauthorized access to systems that might be exploited through this vulnerability, while regular security assessments should be conducted to identify similar insecure command execution patterns in other applications and systems.