1.
A script kiddieor other individual who attempts to portray themselves as being knowledgeable in the area of computer security while having no such knowledge.
The term is generally used to ridicule those who meet this definition without their knowledge, in this case it is generally implied that the word is analogous to blackhat or whitehat. In reality it is meant to imply that the individual has "shit for brains".
<4w50m3r> u no I hav h4x3d paypal like 8 times.
<Sarcastron> Wow, that's awesome, you're totally brownhat.
<4w50m3r> u here that? im brownhat!
See blackhat, whitehat, redhat, skiddie, noob
2.
Derived from hacker jargon White Hat, Black Hat A startlingly incompetent wannabe hacker with malicious intent. Fortunately for the world, his overuse of l33tspeak and Markov-generated technobabble render his malevolence simply amusing.
"heh. This brownhat says he's gonna send a 'multimuscular ILOVEYOU tcpip" virus to 127.0.0.1."
See hack, hacker, hacking, computers, incompetent, idiot, dumbass, fucknozzle