Abstract: A network bridge (14) has an associated malware scanner (16) that serves to concatenate portions of a data file from within data packets intercepted by the network bridge (14) and then scan the data file concerned before the data file is forwarded to its intended recipient by the network bridge (14). The network bridge (14) may be inserted in a network topology without requiring significant network configuration changes. The network bridge (14) may include a packet analysis unit (56) that serves to intercept only data packets having a predetermined network layer protocol or a predetermined application layer protocol.

Abstract: When a file is created on a computer, an archive copy of that file is also created and separately stored. Upon a subsequent access to the active copy of that file, a comparison between the active copy and the full archived copy is made to detect any changes. If there are not any changes, then the active copy of the file is assumed to be clean from malicious alteration and the access request is permitted. If an alteration has been made and is detected, then further countermeasures are triggered, such as full virus scanning of that file or blocking of its use. This archiving and comparison technique may be selectively applied to a subset of file types, such as executable files and dynamic link libraries, which are known to be infrequently modified during normal user operations.

Abstract: An event report, such as a virus detection event, is sent from a reporting computer 2 to a receiving computer 6 via an internet link 4. The report data may take the form of a URL requesting a web page 28 to be provided by the receiving computer 6, the URL bearing an encrypted form 24 of the report data that is used to identify the requested web page as well as pass further information to the receiving computer 6. Alternatively, the report data may be collated in the reporting computer 2 and passed to the receiving computer 6 when a computer virus definition data update is requested. The report data seeks to uniquely identify the event by incorporating the MAC address of the reporting computer 2, the date, time, computer product identifier, version identifier, update identifier and driver triggered. Additionally, a checksum derived from the infected file together with an indication of the corrective action, if any, taken by the reporting computer 2 may be included.

Abstract: Archive copies of active computer files are generated and stored when a computer file is created or copied onto a computer system. These archive copies are compared with the current active copies upon subsequent access to detect malicious alterations in the active copies. If such alterations are detected, then a repair of the active copy may be made by replacing it with the archived copy. This replacement may be subject to user confirmation or user defined rules. The technique may be selectively applied to certain file types, such as executable files or dynamic link libraries, that are known to infrequently change during normal use.

Abstract: A software audit system is provided in conjunction with an anti-virus system. A computer virus scan request received by the anti-virus system (16) is used to trigger an audit data generator (18) to generate audit data. The audit data generator (18) may also serve to ban certain computer programs from execution and monitor the concurrent usage of other computer programs.

Abstract: An anti computer virus program uses a library of virus drivers that includes an indication of whether a particular virus can cause irreparable damage and data indicating enhanced user warnings and actions that might be associated with such viruses. If a detected computer virus is one that can cause irreparable damage, then an enhanced user warning (16) is issued indicating this to the user and a notification (28) of the possibility of such corruption is added into the repaired computer file. The notification may take the form of an electronically signed (30) banner message or the like.