C
Confidentiality
Only the right people can see the data. Everyone else is kept out.
Common controls
encryption
passwords
MFA
access control
file permissions
Violated when
Someone reads or steals data they shouldn't see. An attacker reads emails over open Wi-Fi. A laptop with customer records is stolen.
I
Integrity
The data is correct and hasn't been tampered with. What you see is what was actually saved.
Common controls
hashing
digital signatures
checksums
audit logs
version control
Violated when
Data is changed without permission. A student edits their own grade. An attacker alters a wire-transfer amount in flight.
A
Availability
The system is up and reachable when you need it.
Common controls
backups
redundancy
failover
DDoS protection
UPS / power
Violated when
The system is offline when you need it. A DDoS attack knocks a hospital site offline. Ransomware encrypts every file on a city's servers.