Back-hack is the process of identifying attacks on a system and, if possible, identifying the origin of the attacks. Back hacking can be thought of as a kind of reverse engineering of hacking efforts, where security consultants and other professionals try to anticipate attacks and work on adequate responses.
In some cases, back hacking can mean tracing an attack to an IP address; in other back hacking efforts, security teams can spot "electronic bread crumbs," or bits of information that an attacker leaves behind. Other efforts at back hacking may be largely pre-emptive, as when security consultants or even rogue coders discover vulnerabilities in a system.
In general, back hacking can raise serious issues within an IT community. Some of the vulnerabilities that these investigators find can compromise vital government or business operations. Back hacking is a fundamental part of finding and deterring threats to cyber-security.