Hacking is one of the technical skills available in System Shock 2.

When you are using a device that can be hacked, whether it is a computer, an electronic lock or a Replicator, the MFD display for that device includes a “HACK” panel on the side. Additionally, some devices, such as gun turrets, can be hacked - and made to shoot your enemies instead of you - even though they cannot be otherwise used. You must have some hacking skill in order to be able to hack a device, and Hack Software provides bonuses. Different devices have different skill requirements.

The top of the hacking MFD display describes the effects of successfully hacking the device. The bottom of the screen describes the difficulty of the task, and any bonuses applicable from skills, statistics and equipment. On the far right of the hacking display is the cost in Nanites and a button marked Start. Click Start (or Reset, if you’re already hacking) to pay the cost in nanites and bring up the hacking interface. The hacking interface is a connected set of squares, outlined either in red or light green. The light green squares are the ones you have identified as “safe” while the red squares are dangerous “ICE nodes.” The proportion of safe and dangerous squares is dependent on the difficulty of the hacking task. For every point of CYB, you have a 5% greater chance of influencing any given node, and for every point of hacking skill, you have a 10% greater chance on any given node. Hacking software increases your effective skill by one point per software level, and there may be other effects. Additionally, a high CYB stat decreases the number of ice nodes.

To successfully hack the device, you must get three squares to light up in a straight line. Click on a square to attempt to light it up. The percentage in the upper left of the MFD is the chance you fail to light that square up (this percentage can never fall below 15%, no matter how high your skill). If you fail on a “safe” node, it turns dark and cannot be further hacked. If you fail on an ICE node, you have critically failed the hack. Critically failing to hack most objects breaks them; if you are hacking a turret or a security computer, critical failure sets off the security alarms. Furthermore, critically hacking a broken object in your inventory like a Pistol will instantly destroy it, which is especially painful if you spent a lot of Nanites to modify it or you just broke your only available ranged weapon!