Is the CIA as corrupt as the media says it is?

i know that a normal agency like homeland security or fbi has no right to kill someone. but is it true that the CIA or even the NSA has the right to kill people who happened to have accidently found out some clified information? from the things i here of the CIA they seem like thugs. should we have the CIA running? does the CIA have contract killers for hire? can they just break the law when they please. also who believes the CIA is really involved in drug dealing?