An attacker accessed the names and Social Security numbers of 400 T-Mobile USA customers and also investigative data on a U.S. Secret Service agent's personal PDA.

T-Mobile said it discovered in October 2003 that a hacker broke into one of its internal systems. An investigation revealed that the attacker viewed the names and Social Security numbers of 400 customers, but no credit card numbers. Affected customers were notified early last year and none have reported any problems from the breach, the carrier said in an email statement to SC Magazine.

As T-Mobile, which is based in Bellevue, WA, investigated the crime with the Secret Service last year, a "Secret Service agent discovered an unusual incident on his own handset, perpetrated by the same hacker," according to the company.

The agent's personal account, which contained limited investigative data, was compromised, said Secret Service spokesman Jonathan Cherry.

The spokesman added the data should not have been on his personal PDA and no cases were compromised in the breach but declined to say if the agent was disciplined.

Nicholas Jacobsen was indicted by a grand jury in California on one count of unauthorized impairment of a protected computer and another of unauthorized access to a protected computer last October.

"While coordinating our efforts with the Secret Service to ultimately see this hacker arrested is rewarding, the elimination of any opportunity for unauthorized access to our systems always comes first," T-Mobile USA CIO Bruce Brown said in the statement.

"We continue to monitor for any illegal attempts to access our systems, and to stay one step ahead of those who would try," he said.

www.t-mobile.com