1. Website defacement

2. Anomaly detection systems

2.1 Checksum comparison

2.2 Diff comparison

2.3 DOM tree analysis

2.4 Complex algorithms

3. Signature detection

4. Thresholds and worst cases

A website defacement is the unauthorized substitution of a web page or a part of it by a system cracker. A defacement is generally meant as a kind of electronic graffiti, although recently it has become a means to spread messages by politically motivated cyber protesters or hacktivists.

This is a very common form of attack that seriously damages the trust and …