Presuming you have an International->International connection in Dubai, the issue is not so much "security" as it is Immigration - you will be on one side of immigration, and your friends will be on the other side.
It will NOT be possible for your friends to pass through immigration to meet you (at least, not unless they happen to be departing from Dubai on that same day).
It MAY be possible for you to pass through immigration and enter the UAE. Once you've done that you're free to meet with your friends in the airport, or even leave the airport with them (which likely makes more sense than hanging around the airport for several hours!). On your return to the airport you will need to pass through immigration (and security) again so be sure to leave enough time.
Whether this is possible or not will depend on your citizenship, and thus whether or not you need to obtain a visa to visit the UAE. If you require a visa then the above will still be possible, but will obviously require additional planning and cost in order to obtain the visa.