What are the three basic protection goals (Grundschutzziele) of information security?

Confidentiality, Integrity, and Availability — the "CIA triad."

Every security analysis must address at least these three:

• C — Confidentiality (Vertraulichkeit): only authorised parties can read the data
• I — Integrity (Integrität): data can't be altered without authorisation or by accident
• A — Availability (Verfügbarkeit): authorised users can access data/services when needed

Measures (controls) exist to guarantee one or more of these. Beyond the triad there's a whole family of additional goals (authenticity, non-repudiation, privacy, anonymity…), but CIA is the irreducible core.

Tip: Some frameworks add to it — e.g. the Parkerian hexad adds possession, authenticity, and utility — but CIA is the universal starting point. Watch out for the name clash with the other CIA.