I was wondering if trading my Eth through a client mobile app such as iPhone's "Polo" client for the Poloniex site is secure. I was wondering this because I see the app is not from the Poloniex team, and it's not opensource. Trading through this app is really much easier than on the mobile version of the site, but if my account could be possibly at risk I would avoid using it anyway. I'm concerned mostly on the security of my credentials and the possibility that the app developer may be able to control my accounts or even see some details of my accounts through any other kind of tracking that may be possible through the coded app.
What do you think about my concerns? Am I paranoid or I'm actually considering something that may be possible?
I don't even know if Apple does any kind of control of what the apps does before they're published. As far as I know they're much more careful than Google on andorid's Play store abou that, but that doesn't represent to me any guarantee about this app's (such kind of app's) security.
Please consider Polo/Poloniex just as an example, the question is if it would be more secure using an unofficial app or the browser as client for such sites.