Monitor

Monitor is detection/systemware program by Arasaka's NetWare division. continuously checks each program on a set schedule. making sure that each is functioning properly. If it finds that a program is functioning improperly or has been corrupted by a virus (roll vs the virus STR+1d10). it will de-rezz it (instantaneous for system programs. otherwise roll against the other program's STR), and reload a new version from memory. If the program is missing from its assigned position in the DataFortress. it will sound an alarm. reload a new copy of the program from memory (takes one turn). and then goes and interrogates every active user it can find inside the Fortress (it does incorporate SeeYa subroutines, allowing it to detect invisible netrunners). The interrogation must be defeated via a Decryption program (treat as a Code Gate with Strength: 4). If it detects an unauthorized user. it will try and Trace him back to his real-space location. Each Monitor can check a number of codegates and programs equal to the number of CPUs in the system minus one. It will either check them randomly, or according to a set schedule (usually the Iatter). Of course. the larger the DataFortress. the longer this takes. If detected. it can be killed. Of course. there could be a Monitor set to check the first Monitor...

Source

 * Rache Bartmoss Guide to the Net, pg.150