Is there any way to block permissions on apps?
There are at least two different solutions available for it: LBE Privacy Guard (careful when you're already running JellyBean: do not use the Playstore version then, but rather check with XDA-Developers, as the playstore version causes boot-loops with JellyBean and the dev did not even place a note for it), and PDroid Privacy Protection / PDroid Manager. The latter is more difficult to install, but often preferred: being implemented at OS level, it offers more security.