Can you do this?...
hmm, for me this is a hard question. i dont want to say no, but i'm not sure i want to say yes…
i suppose that it may be an acceptable form of activism, however if i were to deface a website i'd be sure just to mv index.html index.bak.html (or something similar). i personally don't thin that rming data on a site is good at all, unless the site is something like a kiddie porn site, etc.
however, i dont feel that it would be as bad to deface a hacker site as it would be to deface a non-hacker site. you'd think that most hacker sites would be protected more than usual against attack, and the owners of the defaced site would also know how to beter respond.
this is an issue that i have been wrestling with for a while. i do consider myself to be a gray hat, but a light gray one. i've never been a blakhat and the guy who first introduced me to hacking was a whitehat. so these type of issues are always a little difficult for me…
but yes, i would say that defacement as an act of political activism (or if you prefer hacktivism), is more acceptable than if you deface just to put up on the site "Your box was 0wn3d", or something similar.
/me rambles on…