Patent ID: 9703954
Date: 2017-07-11
CPC Classifications: G06F

Claim:
1. A method for providing a computerized system which is protected from malicious programs coming from an external source, the method comprises steps of: a) secretly, and in a manner unknown to authors of external programs, modifying on a temporal basis at a central security authority one or more essential elements of an operating system of the computerized system in a manner which causes all running programs to fail due to an exception which indicates an illegal operation, unless they are subjected to a compatible modification which enables them to run properly; and b) modifying also on the temporal basis at said central security authority each program which is known to be benign in order to comply with said modification of one or more essential elements, thereby to enable proper execution of the program, and running the modified program at the computerized system; which is adapted for a static linking, wherein said modification at the computerized system involves modification to at least one service routine and to a wrapper routine in a standard library, and wherein said modification to each of the benign programs is a compatible modification to a signature of the program; or which is adapted for a dynamic linking, wherein said modification at the computerized system involves maintaining two copies of a dynamic standard library, a first copy of the dynamic standard library under its original name, and a second copy of the dynamic standard library under a modified name, and wherein said modification to each of the benign programs is a compatible modification to call said modified copy of the dynamic standard library.