An employee received an email containing a suspicious attachment. Upon opening the attachment, their computer started displaying numerous pop$-$up advertisements, slowing down the system significantly. Concerned about the security implications, the IT department was alerted to investigate the issue. Following the incident with the email attachment, the IT department conducted a thorough investigation into the employee's computer. They discovered not only pop$-$up advertisements but also unauthorized access to sensitive company files and unusual network activity. Additionally, several files on the computer were encrypted, with a ransom demand displayed on the screen.

Identify the two types of malware most likely responsible for the described scenario.