Complex sentence: During November 2012 an Exploit of Yahoo! Mail was sold at $700 by an Egyptian Hacker which allows Hijackers to hack Yahoo! Mail user accounts and redirects the users to a malicious website.
Split into simpler sentences: During November 2012 an Exploit of Yahoo! Mail was sold at $700 by an Egyptian Hacker. That exploit allows Hijackers to hack Yahoo! Mail user accounts and redirects the users to a malicious website.