Type Macro virus
Date Discovered 1996.07.25
Place of Origin Alaska? South Africa?
Source Language Visual Basic
Platform MS Excel
File Type(s) .xls
Infection Length 2 macro modules
Reported Costs

Laroux is the first wild Microsoft Excel virus.


Laroux consists of two macros "Auto_Open" and "Check_Files", which are stored in a hidden datasheet named "laroux". It looks for the presence of the file PERSONAL.XLS, the file containing all recorded macros available to all Excel files, and if it finds it, adds the macro "laroux". If it finds no such file, it creates it. The virus then infects any Excel workbook saved or accessed.


Laroux was found in Alaska and South Africa. No indication is given as to whether or not the virus originated form one of these locations. Both the locations were the offices of oil companies. The companies were reportedly paralysed.

Other Facts

While the Concept macro virus was able to work on any system that could run Microsoft Word including the Macintosh, the original variants of Laroux could only run on Windows.


Mikko Hypponen. F-Secure Antivirus, F-Secure Virus Descriptions : Laroux.

Alex Haddox. Symantec AntiVirus Research Center, Volume 1, Issue 1 1996.09.01

Andy Nikishin, Mike Pavluschik, Denis Zenkin. Macro-Viruses: Genesis, Truth about the Threat and Methods of Protection.

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