Convicted hacker Robert Moore, who is set to go to federal prison this week, says breaking into 15 telecommunications companies and hundreds of businesses worldwide was incredibly easy because simple IT mistakes left gaping technical holes.

Moore, 23, of Spokane, Wash., pleaded guilty to conspiracy to commit computer fraud and is slated to begin his two-year sentence on Thursday for his part in a scheme to steal voice over IP services and sell them through a separate company. While prosecutors call co-conspirator Edwin Pena the mastermind of the operation, Moore acted as the hacker, admittedly scanning and breaking into telecom companies and other corporations around the world.

"It's so easy. It's so easy a caveman can do it," Moore told InformationWeek, laughing. "When you've got that many computers at your fingertips, you'd be surprised how many are insecure."

Pena, who is charged with acting as a legitimate wholesaler of Internet-based phone services as part of what the government called a "sophisticated fraud," fled the country a year ago and is wanted as a fugitive. Assistant U.S. Attorney Erez Liebermann said Pena allegedly stole and then sold more than 10 million minutes of service at deeply discounted rates, netting more than $1 million from the scheme.

Acting as the operation's technical muscle only netted Moore $20,000 of the haul, according to Moore.

The government identified more than 15 VoIP service providers that were hacked into, adding that Moore scanned more than 6 million computers just between June and October of 2005.AT&T (NYSE: T) reported to the court that Moore ran 6 million scans on its network alone.

However, the names of the companies Moore and Pena hacked into don't appear in the court documents--aliases are used instead--and Moore said he wasn't at liberty to identify them publicly.

Liebermann noted that one small telecom went out of business because of expenses the company incurred during the break-in. The company legitimately routed its own VoIP traffic through a larger telecom and was forced to pay the other company for the calls that Pena and Moore fraudulently sent through their network. "They had to eat the bill and were unable to remain in business," added Liebermann.

Default Passwords: A Hacker's Dream

Moore said what made the hacking job so easy was that 70% of all the companies he scanned were insecure, and 45% to 50% of VoIP providers were insecure. The biggest insecurity? Default passwords.

"I'd say 85% of them were misconfigured routers. They had the default passwords on them," said Moore. "You would not believe the number of routers that had 'admin' or 'Cisco0' as passwords on them. We could get full access to aCisco (NSDQ: CSCO) box with enabled access so you can do whatever you want to the box. ... We also targeted Mera, a Web-based switch. It turns any computer basically into a switch so you could do the calls through it. We found the default password for it. We would take that and I'd write a scanner for Mera boxes and we'd run the password against it to try to log in, and basically we could get in almost every time. Then we'd have all sorts of information, basically the whole database, right at our fingertips."