CVE-2001-0667 in Internet Explorer
Summary
by MITRE
Internet Explorer 6 and earlier, when used with the Telnet client in Services for Unix (SFU) 2.0, allows remote attackers to execute commands by spawning Telnet with a log file option on the command line and writing arbitrary code into an executable file which is later executed, aka a new variant of the Telnet Invocation vulnerability as described in CVE-2001-0150.
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Analysis
by VulDB Data Team • 01/16/2025
This vulnerability represents a critical command execution flaw affecting Internet Explorer versions 6 and earlier when integrated with Services for Unix 2.0 version 2.0. The security issue stems from how the Telnet client component handles command line arguments and file operations within the Windows environment. The vulnerability operates through a sophisticated attack vector that leverages the interaction between the web browser and the Unix services component, creating an unexpected execution path that bypasses normal security boundaries. The flaw specifically exploits the Telnet client's handling of log file options, allowing attackers to manipulate the execution flow through carefully crafted command line parameters.
The technical implementation of this vulnerability involves the exploitation of the Telnet client's process spawning mechanism when invoked through Internet Explorer. When a user visits a malicious web page containing specially crafted Telnet commands, the browser executes a Telnet process with a specified log file option. The attacker can then write arbitrary executable code into a file that gets created or modified during this process, which subsequently gets executed by the system. This represents a classic case of insecure command line argument handling where the application fails to properly sanitize or validate input parameters before executing system commands. The vulnerability demonstrates poor input validation practices and inadequate privilege separation between different system components.
The operational impact of this vulnerability extends beyond simple remote code execution to encompass potential system compromise and privilege escalation scenarios. Attackers can leverage this flaw to execute arbitrary commands with the privileges of the user running the Telnet client, potentially leading to full system compromise. The attack requires minimal user interaction beyond visiting a malicious webpage, making it particularly dangerous in phishing scenarios. The vulnerability affects the broader Windows ecosystem by exploiting the integration between Microsoft's Windows Internet Explorer and the third-party Services for Unix component, highlighting the risks associated with component integration in enterprise environments. This particular variant builds upon the original Telnet Invocation vulnerability described in CVE-2001-0150, demonstrating how similar flaws can manifest in different contexts.
Mitigation strategies for this vulnerability should focus on immediate patching of affected systems and removal of unnecessary components. Organizations must ensure that Services for Unix 2.0 is either updated to a patched version or completely removed from systems where it is not essential. Browser security configurations should be reviewed to limit the execution of potentially dangerous components, and users should be educated about the risks of visiting untrusted websites. Network-level protections such as firewall rules and web content filtering can provide additional layers of defense. This vulnerability aligns with CWE-78, which addresses improper neutralization of special elements used in OS commands, and maps to ATT&CK technique T1059.001 for command and script interpreter execution. The remediation process should also include comprehensive system auditing to identify any other potentially vulnerable components that might interact with similar command execution mechanisms, as this represents a broader class of vulnerabilities in system integration security.