1. A computer implemented method for preventing malicious code from propagating in a computer, the method comprising the steps of: a blocking-scanning manager detecting attempted malicious behavior of running code; responsive to the detection, the blocking-scanning manager blocking the attempted malicious behavior; the blocking-scanning manager generating a signature to identify the code that attempted the malicious behavior; the blocking-scanning manager detecting code identified by the signature; and the blocking-scanning manager blocking the execution of the identified code.