A security official on Friday told Aljazeera in Rabat that an 18-year-old Moroccan youth had been arrested.

The arrest followed a tip off by the US's Federal Bureau of Investigation, the official said.

Farid Essebar of Morocco, and Atilla Ekici, 21, of Turkey, are believed to have written and unleashed the Zotob and Mytob worms that hit the internet less than two weeks ago, the FBI said in Washington on Friday.
   
The worms caused computer outages at more than 100 US companies, including major media outlets such as CNN, the New York Times and ABC News.
   
The worms did not cause widespread havoc along the lines of previous malicious software programs like SQL Slammer and MyDoom. 

Flaw
   

"The swift resolution of this matter is the direct result of effective coordination and serves as a good example of what we can achieve when we work together"

Louis Reigel,
FBI Cyber Division

Zotob and Mytob targeted a recently discovered flaw in the Plug and Play feature of Microsoft's Windows 2000 operating system.
   
Users who heeded a prior warning from Microsoft and updated their systems were not victimised by the worms.
   
Those who did not keep their systems up to date could have their computers taken over by remote servers.
   
Microsoft and the FBI helped overseas authorities track down those responsible, the FBI said.
   
"The swift resolution of this matter is the direct result of effective coordination and serves as a good example of what we can achieve when we work together," FBI Cyber Division Assistant Director Louis Reigel said in a press release.