Crackers (who are more popularly known as black hats or cyber terrorists) are technologically adept hackers who specialize in perpetrating unauthorized system breaches and database penetrations. They are the hacker type most associated to the "hacker" term in popular culture; that is, they're malicious, tech-savvy, and dangerous online outlaws who are willing to inflict thousands of dollars' worth of network infrastructure damage for personal gain, profit, political motivations, schadenfreude-based entertainment, the promotion of a social cause, or a multitude of other reasons.
Among the three types of hackers
And dangerous kind because of the manner by which they perpetrate their cyber or system attacks. While a grey hat tends to do passive penetration testing to maintain his anonymity and a white hat actually works with vendors in order to fix a discovered security hole, a black hat penetration often involves unauthorized stealing, editing, modifying, and/or erasing of data.
Black hats are deemed as the most destructive
The key difference between these virtual villains and white knights is that the former performs his dastardly and detrimental deeds without any authorization from the system administrator or webmaster, which a white hacker would never do. As for the key difference between black hats and grey hats, black hats tend to eschew passive hacking techniques in favor of outright hacking invasions that deal a lasting and palpable blow to their intended targets.
Black hats are notorious for distributing
Spam, worms, viruses, trojans, botnets.
And many other types of malware to different networks in order to exploit any known or undisclosed server vulnerabilities at their own behest. The term may also encompass crackers who are experts at removing copy restriction methods on software such as CD check, date checks, hardware key, serial number, trial or demo version as well as software annoyances like adware and nag screens.
What's more, these web rapscallions would never reveal vulnerability-related information to the public or to administrators because doing so would present a conflict of interest on their part. They want systems to remain unfixed and susceptible to hacker attacks because patches will greatly decrease the effectiveness of their assaults, invasions, and exploits. Indeed, black hats are adamantly against the white hat policy of full disclosure because they view system integrity and security as more the responsibility of vendors and developers than that of hackers.