Nimda is a virus — a #malicious file-infecting #computer #worm. The first released advisory about this threat was issued on 18 September 2001. Nimda affected both user #workstations running Windows 95, 98, NT, 2000, or XP, and servers running #Windows NT and 2000. The worm's name comes from the reversed spelling of "admin". F-Secure found the text "Concept Virus V.5, #Copyright 2001 R.P. #China" in the #Nimda code, suggesting its #country of origin.