"Internet Security - Weaknesses and Targets" is based on "Internet- & WWW-Technologies" and gives a detailed introduction on problems concerning Internet and Intranet security. After starting with some remarks on risk analysis and computer crimes, security weaknesses and targets are discussed in detail. Beside others the following topics are discussed in detail: human factor and technical failures, attacks on accounts and passwords, attacks on Internet protocol, misuse of design and programming errors, weaknesses in common operating systems, targets in the WWW, and viruses. The lecture course concludes with a discussion about the possibilities to detect attacks and intrusions and also describes ethical issuses.