There are many security concerns that people should be aware of before using a Facebook proxy. Some of these issues are minor and will not bother the regular user. On the flip side, some of these issues are quite sever and could cause major damage to your Facebook account.
The main issue is that many of the proxies have ways of not only monitoring your activity but logging it as well. For example, if you logged in, they may be able to log your password. They may also be able to parse through (look at) everything you see on your screen, which means that they could gain access to your private information.
Another issue is that some of these proxies have ways of sneaking code onto your computer (virus, trojan, et cetera). While this process is not very common, it can happen in some circumstances (especially those proxies that require you to download software, which are not recommended proxies). Most Facebook specific proxies will not require you to download software. If a Facebook unblocking method requires you to download something, you should simply try another service as the risks of virus infection, or information leaking, is not worth the usage of the proxy.
