which elements of the CIA triad most impacts Point$-$of$-$Sale $($POS$)$ System

Identify the most concerning threat vector for point$-$of$-$sale $($POS$)$ system example $($e$.$g$.,$ SQL injection, DDOS, malware, etc.$)$

describe a threat based on the threat vector for the point$-$of$-$sale $($POS$)$ system.

describe the plan you recommend implementing to protect from the defined threat.

identify the residual risk level $($High$,$ Medium, or Low$).$