1 Stress echocardiogram: This is an echocardiogram that is performed while the person exercises on a treadmill or stationary bicycle. 2  This test can be used to visualize the motion of the heart's walls and pumping action when the heart is stressed.
Viruses require an active host program to cause damage and infect other executable files or documents, while worms are stand-alone malicious programs that can self-replicate and propagate via computer networks, without human help.
Stuxnet has three modules: a worm that executes all routines related to the main payload of the attack; a link file that automatically executes the propagated copies of the worm; and a rootkit component responsible for hiding all malicious files and processes, preventing detection of the presence of Stuxnet.