Concon

A Blue Screen of Death caused by typing "C:\con\con" into the Run dialog.

Con/con is a computer bug that appeared in the Windows 95 and Windows 98 operating systems. The name comes from the fact that referring to the file "C:\con\con" would crash these systems. This was a particular case of a more general bug, where the system failed to respond correctly to file paths containing multiple device file names. (In the example, "con" is the device file name for the console device.) Such file paths are invalid on Windows, because device file names are reserved words. Even though the system would report an error if "C:\con" were accessed, the system would miss the attempted reference to "con" in the case of accessing "C:\con\con".

This bug was considered a security vulnerability because malicious web pages could crash systems with links such as file:///C:/con/con. A patch released by Microsoft in March 16, 2000 fixes the bug and the vulnerability.

External links

• Microsoft Security Bulletin (MS00-017)