First we explain about CIA:- CIA means confidentiality, integrity and availability. It forms a triad of confidentiality+integrity+availability.
Now, we explain the Spam and Phishing threat and the example of spam refers the electronic junk mail or unwanted mail that are received on your computer. The example of phishing is email and link to collect some important information like financial information and personal information. Here triad affected is confidentiality because Attacker stolen the private information.
Virus is a small piece of malicious code or program that are programmed to harm your computer bycopying itself to the another file. it danmages the files and hard drive of the computer. malware is the example of virus threat. CIA affected in virus is integrity because it alters or delete ihe important information of a file.
Worms:-It is a self replicating program which affect the entire network. The example of worm is email worm which affect the email by doubling the file extension and file sharing worm which affected the file by copying itself into another program. The CIA affected by worm is availabilty of System by depleting system resources.