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First published: 11th December 1999
Destructive macro virus erases files on hard disk
Espoo, Finland - Data Fellows, a leading provider of centrally-managed, widely distributed security solutions, is warning computer users about the W97M/Thus virus, also known as the Thursday virus. Thus is a virulent and widespread virus which can destroy information on a user's computer. It activates on December 13th.
Thus is a macro virus that spreads via Word 97 and Word 2000 files which have been downloaded onto a user's computer from e-mail attachments or infected diskettes or CDs. Data Fellows' F-Secure Anti-Virus erases the virus, if the software has been updated since September.
When the user opens an infected document, the virus infects the system, including the global template as well as every currently open document in Word. After that, every document that is created, opened or closed will be infected. On December 13, it deletes all files from all directories on the "C:" drive. Prior to that date, the virus does not manifest itself in any way - it shows no messages and the user will not see that his computer is infected until its too late.
"The worrying thing about this virus is that its really common", says Mikko Hypponen, manager of anti-virus research at Data Fellows. "The Thus virus was discovered at the end of August, 1999, and it has been reported in the wild globally since September."
If a user's computer is protected by anti-virus software which has been updated since September 1999, problems are unlikely to occur. Users should double-check to make sure their software is up-to-date and able to detect the Thus virus. Also, it is advisable to make back-ups of important data. If in any doubt, download the free evaluation version of F-Secure Anti-Virus from the Data Fellows website now.