Attackers is divided into many types. i will pick some core type 4 u..
1. Hackers. The meaning of hacker has changed from the past. They dun do any serious thing to the system. They just hack the system as to find the vunleravbility of system and then notice the administrator who manages, operate, and control the system to fix up. This becauses the ethics has merged with the hacker recently. They usually called them as the ethical hacker or the code of ethics hacker. Normally, they have a high level of knowledge and skill of IT

*notice - actually they are spilted into many categories such as white hat hacker, IT profess.. and .etc

2 Cracker - This type is somewhat dangerous. They have a high level of knowledge and skill as the same hacker. Yet they harm the system because they ego, some purpose, and fun

3. Script kiddies... They are much and much more in the world ....They think they have excellent knowledge but actully they are not. They just have some small skill and knowledge such as know abt some languages not expert such as C/ C++, perl , and some command namely linux. They always use the tools that the hacker create. They can not find the vulnerability of system to exploit. Anywy, they r suck..think they are patent in hacking (perhaps this word impolite ..sorry na.....pls dun kick me off na admin) Because the majority of number of script kiddies has increased, the server or the system is attacked much more than before.

4. Spies..They have a high level of knowledge and skill. They exploit the system as to own purposes such as finance, and reward. They fundamentally steal info for money

5. Employees. They attempt to steal the info as to reward for themselves. They use social engineering method to gain the advantages. In the fact, they have not any skill and knowledge of IT
6. cyberterrorist---- Expert skill and knowledge within them. They take time to hack and destory the Internet rather than companies or small thing. They always collapse the government work especially USA ja...
7........too long.....u can find info. on the Internet.....i think.....lazy to write ......
Anywy ..i just wanna give some info to some ppl who wanna be attacker....what type of attacker do u wanna be? pls ask ur mind na :P