Post-infection virus protection through data restoration using mirrored data that has been obtained prior to the virus infection. A network appliance in a network mirrors the data of a number of computers in an ongoing manner. An anti-virus module of the network appliance scans data received from a computer to determine whether the computer is infected by a virus. If no virus is identified, the network appliance uses the received data to update a mirrored copy of the computer's data. If, however, the network appliance identifies a virus, the mirrored copy is not updated. Instead, the previous mirrored copy, which represents a pre-infection state of the data, is used to restore the infected computer to its pre-infection state. In this manner, a single copy of an anti-virus utility executed at the network appliance can protect an arbitrary number of computers, which do not require their own anti-virus software.