SS
Players with -2.0 or worse will be attacked in 1.0 systems
Players with -2.5 or worse will be attacked in 0.9 systems
Players with -3.0 or worse will be attacked in 0.8 systems
Players with -3.5 or worse will be attacked in 0.7 systems
Players with -4.0 or worse will be attacked in 0.6 systems
Players with -4.5 or worse will be attacked in 0.5 systems

Standings
However, if it gets too low (-5.00 or below), you run the risk of being attacked by that faction's Navy, much like low security status can get you in trouble.