بسم الله الرحمن الرحيم
(Fatwa: 1121/1204/L=11/1437)
It is wrong to rent shop with security. You should not take the security money rather take the normal rent. Likewise, it is not lawful for one who took a shop with security to keep it without any amount of rent; it is getting benefit by giving debt which is unlawful.
Allah knows Best!
Darul Ifta,
Darul Uloom Deoband