Skid - easy (4 letters)
1 - open
2 - kill
3 - exec
4 - hack
5 - comp
Anonymous - medium (6 letters)
1 - hacker
2 - dragon
3 - denial
4 - window
5 - ubuntu
Gh0st - hard (8 letters)
1 - password
2 - phishing
3 - computer
4 - keyboard
5 - potatoes