1. A method for scanning a computer memory for obfuscatory pestware, comprising: examining, by a pestware detection module, an import address table (IAT) of an executable object in the computer memory to identify at least one subroutine of the executable object that calls an application program interface (API), the API having a fixed address in the computer memory, the API being known to appear in a particular kind of polymorphic or metamorphic pestware; locating, by the pestware detection module, the at least one subroutine within the executable object; and searching, by the pestware detection module, for a predetermined check value at a known offset relative to an address, in the computer memory, at which the at least one subroutine calls the API, the predetermined check value identifying the executable object as the particular kind of polymorphic or metamorphic pestware when the check value is found at the known offset.