According to the ENISA Threat Landscape 2024, what is the single biggest threat to data and information?

Ransomware tops the list — ahead of malware and social engineering.

ENISA's 2024 top threats, roughly in order:

1. Ransomware
2. Malware
3. Social engineering
4. Threats against data (data breach)
5. Threats against availability (Denial of Service)
6. Information manipulation
7. Supply-chain attacks

Why ransomware leads: it monetises an intrusion directly and at scale — encrypt the victim's data, demand payment, and (increasingly) also threaten to leak the stolen copy. It hits all three CIA goals at once: availability (locked files), confidentiality (leaked data), and integrity (tampered systems).

Resource: ENISA publishes this report yearly — enisa.europa.eu.