investigate 4 specific and recent viruses/worms, software exploits, or malware packages (a total of 4, not 4 of each they may they may be from the same category, or multiple). These should be threats in the last ~6 years. Note also the "specific" - for example, you should not just write about "randsomware" or similar, but research the details about a specific/notable example of it. For each summarize: . a brief description of the threat when did it happen / get discovered, how did it work / what was affected the impact that it had . what approach or approaches are/were effective at mitigating that threat.