Complex sentence: AOHell, released in early 1995, was a program designed to hack AOL users by allowing the attacker to pose as an AOL staff member, and send an instant message to a potential victim, asking him to reveal his password.
Split into simpler sentences: AOHell, released in early 1995, was a program designed to hack AOL users by allowing the attacker to pose as an AOL company representative. A phisher might pose as an AOL staff member and send an instant message to a potential victim, asking him to reveal his password.