Ethical hackers are claiming a $10,000 prize for successfully breaking into the webmail account of the chief exec of StrongWebmail after the firm issued a "hack us if you can" challenge.

StrongWebMail runs a callback verification system so that, in theory, even if someone obtains a user's login details they can't read email from the account without also having access to the phone associated with a particular account. Logins into StrongWebMail from previously unused machines need this secondary form of confirmation.

The US start-up was so confident of its claims that its Darren Berkovitz published his account name and password in laying down a $10K challenge to hackers to break into his account and find out his schedule for 26 June. StrongWebMail's features include calendar and to-do lists as well as webmail.

Security researchers Lance James, Aviv Raff and Mike Bailey obtained the information and claimed their prize on Thursday. StrongWebMail confirmed that the data obtained was correct, but are holding off in paying out the prize because they are yet to be convinced the Ruff and co stuck to competition rules. The rules prohibit the use of social engineering trickery (such as tricking or paying an insider to hand over account access).

The group of researchers maintain they played fair and used a cross-site scripting (XSS) vulnerability to access the target account after first registering an account of their own with the service. The trio are withholding details out of concerns the same approach might be used to access other accounts without permission, and in line with competition rules.

James, Raff and Bailey demonstrated their attack on a test account set up with StrongWebMail by IDG. But the compromise was possible only after the NoScript extension on the Firefox browser of the XP machine used in the test was disabled, IDG reports.

Hacking competitions such as the one established by StrongWebMail might make for good publicity but they don't prove much. Even if no one wins a particular challenge it doesn't follow that a system is unhackable - just that it wasn't broken this time around. ®