Who has the upper hand in the cyber war between criminals and the law?
Young Russian IT graduates have a fearsome reputation for their ability to pierce cyberdefences.
The BBC met one hacker to try to discover why he had become a hacker - and what made him so good.
Andrei used to hack for fun -- and to test his abilities.
Hackers For Hire was broadcast on BBC World Service at 1006 GMT on 11 March 2010