An Australian man pleaded guilty to breaking into eBay and a local bank to steal AU$42,000 (about $34,000), in a case that demonstrates the problem of account takeovers on the auction site.

Dov Tenenboim, 21, of the Sydney suburb of North Bondi, stood accused of breaking into at least 90 different eBay seller accounts last year, mostly by guessing passwords. Tenenboim frequently figured out the credentials by matching usernames to passwords, prosecutors said. Other times he hacked into email accounts.

Following a familiar route, Tenenboim targeted users with highly favorable feedback ratings from their eBay peers. Posting under the guise of a trusted user with an established account makes it easier to dupe buyers.

After hacking the accounts, Tenenboim used them to advertise non-existent iPods, according to the Sydney Morning Herald. He also hacked into the Commonwealth Bank. He pleaded guilty to two counts of making a false statement to obtain money, two counts of obtaining money by deception and four counts of committing an unauthorized computer function. Tenenboim faces a maximum of 11 years in jail and fines of $9,900.

Account takeovers have been a persistent problem on eBay. Over the past several weeks, we've observed hundreds of fraudulent auctions being offered by users with unblemished records. Such hijackings are on the rise, according to a small but vocal group of eBay users, who also claim the breaches are the result of an unpatched security hole in the company's defenses.

eBay strongly denies such a hole and says the takeovers are the result of users having their log-in credentials snatched through lax passwords and phishing attacks. Tenenboim's methods appear consistent with such statements.

But eBay can't be let off the hook completely. The company employs lax password requirements that, for instance, allow a user ID of james34231 and a password of james34. (To be fair, Google Mail allowed the same combination, though the site warned it was only "fair.")

What's more, eBay, like the vast majority of online services, has no mechanism in place to allow account holders to log in using security keys that generate random numbers every minute or so. Such devices would render most current password attack methods ineffective.

eBay has said it is in the early stages of testing such a system for its PayPal users, and a spokeswoman says the key will also work on eBay. ®