You are the IT manager at a mid$-$sized company, and one morning, you receive multiple complaints from employees who cannot access the company's internal file server. Upon investigation, you discover that the server was hit by a ransomware attack overnight. All critical files are encrypted, and a ransom note is demanding payment in exchange for the decryption key.

Which elements of the CIA triad were violated in this scenario, and what immediate steps should be taken to mitigate the impact of the attack?