CVE-1999-1370 in Internet Explorer
Summary
by MITRE
The setup wizard (ie5setup.exe) for Internet Explorer 5.0 disables (1) the screen saver, which could leave the system open to users with physical access if a failure occurs during an unattended installation, and (2) the Task Scheduler Service, which might prevent the scheduled execution of security-critical programs.
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Analysis
by VulDB Data Team • 04/19/2026
The vulnerability described in CVE-1999-1370 represents a critical security flaw in the Internet Explorer 5.0 setup wizard component known as ie5setup.exe. This issue demonstrates poor security design practices during the installation process where the setup wizard deliberately disables fundamental system security mechanisms without proper justification or user consent. The vulnerability specifically targets two essential Windows security services that are crucial for maintaining system integrity and protecting against unauthorized access.
The technical flaw manifests through the automatic disabling of the screen saver functionality during unattended installations, creating a significant security risk when the installation process fails or is interrupted. When a system remains unattended during installation, the disabled screen saver leaves the desktop accessible to anyone with physical access to the machine, potentially enabling unauthorized users to exploit the system during the vulnerable installation window. This behavior directly violates security best practices and creates an attack surface that malicious actors could leverage to gain unauthorized access to systems during critical installation phases.
Additionally, the setup wizard disables the Task Scheduler Service, which represents a more sophisticated security risk as it affects the system's ability to execute scheduled security-critical tasks. This disabling of the Task Scheduler Service can prevent essential security updates, backup operations, and other automated security measures from executing properly, potentially leaving systems vulnerable to attacks that could have been mitigated through scheduled security operations. The vulnerability is particularly concerning because it affects the core Windows security infrastructure rather than just application-level settings.
From a cybersecurity perspective, this vulnerability aligns with CWE-665 Improper Initialization and CWE-310 Cryptographic Issues, as it demonstrates improper system initialization that leaves critical security services disabled. The operational impact extends beyond the immediate installation phase, as the disabled services may remain inactive even after installation completes, creating persistent security weaknesses. This vulnerability also relates to ATT&CK technique T1059 Command and Scripting Interpreter, as it effectively disables system security mechanisms that would normally prevent unauthorized access and execution of malicious code.
The risk assessment for this vulnerability is elevated due to its potential to create persistent security gaps during and after installation processes. Organizations deploying Internet Explorer 5.0 would face significant security exposure, particularly in environments where physical security controls are inadequate or where unattended installations are common. The vulnerability essentially creates a false sense of security by presenting a seemingly legitimate installation process that actually undermines fundamental system security controls.
Mitigation strategies for this vulnerability require immediate attention through system hardening procedures and manual re-enabling of the disabled services. Organizations should implement comprehensive patch management processes to ensure that vulnerable Internet Explorer 5.0 installations are upgraded to secure versions, while also conducting security audits to verify that screen saver and Task Scheduler services have been properly re-enabled. The vulnerability underscores the importance of security-conscious software design practices and highlights the need for proper security testing during software development lifecycle phases, particularly for installation and setup components that interact with system security services.