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DOS Device in Path Name Vulnerability

A security vulnerability exists in Windows 95, 98 and 98 SE which could cause a user’s system to crash, if they attempted to access a file or folder whose path contained certain reserved words.


DOS device names are reserved words, and cannot be used as folder or file names. When parsing a reference to a file or folder, Windows correctly checks for the case in which a single DOS device name is used in the path, and treats it as invalid. However, it does not check for the case in which the path includes multiple DOS device names. When Windows attempts to interpret the device name as a file resource, it performs an illegal resource access that usually results in a crash.

Because it is not possible to create files or folders that contain DOS device names, it would be unusual for a user to try to access one under normal circumstances. The chief threat posed by this vulnerability is that a malicious user could attempt to entice a user to attempt such an access. For instance, if a web site operator hosted a hyperlink that referenced such a path, clicking the link would result in the user’s machine crashing. Likewise, a web page or HTML mail that specified a local file as the source of rendering information could cause the user’s machine to crash when it was displayed. If this happened, the machine could be put back into normal service by restarting it.

Affected Products

  • Windows 95, 98 and 98 SE


Software patches are available from the following locations:

Further Details

Source: Microsoft Corporation

Reference: Microsoft Corporation

Updated: March 16, 2000

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