Wired writes Teen Who Hacked CIA Director's Email Tells How He Did It. As are many hacks now, it's less an issue of breaking of code and more social hacking of the companies offering you services.
He says they first did a reverse lookup of Brennan’s mobile phone number to discover that he was a Verizon customer. Then one of them posed as a Verizon technician and called the company asking for details about Brennan’s account.
‘[W]e told them we work for Verizon and we have a customer on scheduled callback,’ he told WIRED. The caller told Verizon that he was unable to access Verizon’s customer database on his own because ‘our tools were down.’
After providing the Verizon employee with a fabricated employee Vcode—a unique code the he says Verizon assigns employees—they got the information they were seeking. This included Brennan’s account number, his four-digit PIN, the backup mobile number on the account, Brennan’s AOL email address and the last four digits on his bank card.
‘[A]fter getting that info, we called AOL and said we were locked out of our AOL account,’ he said. ‘They asked security questions like the last 4 on [the bank] card and we got that from Verizon so we told them that and they reset the password.’ AOL also asked for the name and phone number associated with the account, all of which the hackers had obtained from Verizon.
On October 12, they gained access to Brennan’s email account, where they read several dozen emails, some of them that Brennan had forwarded from his government work address and that contained attachments. The hacker provided WIRED with both Brenann’s AOL address and the White House work address used to forward email to that account."