Please find some basic info about the security threats. This is only the basic and most common info so I am sure there is more!
Attacker Ability Threat
Eavesdropper Intercept messages Read contents of message
Intruder Compromised host Tamper with contents of message
Impersonator Remote social engineering Trick party into giving information
Extortionist Remote / botnet Disrupt network services
Hope you enjoy it.
Do you won’t more? Post it in comments are I will try to add due to course.