Case Study 5-2 Security Breach at Yahoo! On September 23, 2016, it was revealed that Yahoo! joined other high profile companies like Home Depot Inc., Target Corp, Anthem, and Blue Cross as a victim of cyber-attacks. In this incident, which began in 2014, 500 million Yahoo! user accounts were stolen. This made it one of the largest security three times the size of other attacks. In December 2016, Yahoo! revealed yet another breach had occurred in 2013. In that incident one billion user accounts were compromiseddouble the size of the 2014 attack.* The stolen information included names, e-mail addresses, telephone numbers, dates of births, and encrypted passwords. Some encrypted or unencrypted security questions and answers were also included in this list. According to the company, unprotected passwords, payment card data, and bank account information have not been compromised. Yahoo! urged its users to change their password and security questions right away and to review their accounts for suspicious activities.* Users should choose strong passwords and update their security questions. A password manager could also be helpful for generating strong passwords and storing them with related security questions and answers. It is not clear why a breach that took place in 2014 was revealed in 2016 and nearly two months after the first appearance of the dumped data on the dark Web where it was being sold by a user who had also sold dumps of data from MySpace and LinkedIn. It is also not clear the extent to which passwords were protected by Yahoo! The company also did not encrypt all the security questions that it stored.

* Answer the following questions:

1.According to the case, how many Yahoo! user accounts were stolen in 2013?

2. What types of information were stolen?

3.When did Yahoo! find out about the one billion user accounts breach?

4. According to the case, did Yahoo! encrypt all the security questions that it stored?