cracking the ransomeware

Background: The first thing Kenya does when she arrives at work is to check her email.  On this particular day, she received an email stating she won a $100 gift card in a sweepstakes game.  Kenya sometimes participates in various sweepstakes so she decided to click on the link and stepped away from her desk.  When she returned and logged into her computer, she was greeted with a message that her computer has been locked and she will need to pay a ransom before she can regain access.  Frantically, Kenya called her technology office and upon their inspection, confirmed Kenya was hit with a ransom attack. 
Ransomware is a dangerous malware that can block access to any connected device infected with the malicious code and restricts access until the user pays a ransom amount. It is often spread through phishing emails that contain malicious attachments or sometimes through drive-by downloading. Drive-by downloading occurs when a user unknowingly visits an infected website and then malware is downloaded and installed without the users knowledge.
Please address the following:
    How are computers vulnerable to ransomware?
    Can ransomware be cracked without paying the ransom amount?

The following may be of assistance:
Trend Micro. (n.d.). RansomwareLinks to an external site.. Retrieved from https://www.trendmicro.com/vinfo/us/security/definition/ransomware