What types of deliberate manipulation threaten information security?

Deliberate manipulation includes internet attacks, unauthorized access, eavesdropping, availability attacks, DDoS, malware, and drive-by infections.

Categories of intentional attacks:

• Internet-based attacks — Exploiting web-facing services and applications
• Unauthorized system access — Breaking into systems without permission
• Eavesdropping and data modification — Intercepting or altering data in transit (man-in-the-middle)
• Availability attacks — Disrupting systems so legitimate users can't access them
• DDoS (Distributed Denial of Service) — Flooding a target with traffic from many compromised machines
• Viruses, worms, and trojans — Self-replicating or disguised malware
• Drive-by infections — Malware delivered simply by visiting a compromised website, no click needed

Real-world example: In 2010, hacktivists launched the "Operation Payback" DDoS attack on PostFinance (Swiss financial services) after PostFinance froze WikiLeaks' account.

Go deeper:

• Cyberattack (Wikipedia EN) — the landscape of deliberate attacks and how they are classified.
• Denial-of-service attack (Wikipedia EN) — how DoS/DDoS floods exhaust a target's resources.