Virus.DOS.C0m.263 is a dangerous file overwriting virus on DOS, it is named by the file extension replacing in the payload.


When the virus is run, it overwrites the file head of every DOS executable in the current directory. When an infected program is run, the virus displays the message:

EXEC Failure

And return to DOS without running the original program.


The virus activates on every Tuesday.

It renames the file extension by replacing the letter "O" with the digit "0" of COMMAND.COM file that is located in the upmost directory of C:. And it displays the message:

Error reading drive C:


The system may fail to recognize the file due to the change of its extension.

It is easy to restore the original extension but the virus may change it again as long as the infected files are not cleared.





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