Creating which of the following is how a hacker can insure his ability to return to the hacked system at will?

A. rootsec

B. checksum

C. CRC

D. backdoors

E. None of the choices.

Explanation:

A backdoor refers to a generally undocumented means of getting into a system, mostly for programming and maintenance/troubleshooting needs. Most real world programs have backdoors. Creating backdoors is how a hacker can insure his ability to return to the hacked system at will.