Web attic Dropbox has admitted spammers got hold of its users' email addresses after an employee reused his or her work password on a website that was subsequently hacked.
Suspicions of a breach at the online storage service arose two weeks ago when punters received floods of unwanted messages touting gambling sites at addresses they used exclusively with their Dropbox accounts.
The company launched an investigation, which confirmed these fears were well-founded. Most of the blame was levelled at an unnamed employee who reused his or her Dropbox password for an account on a third-party website that was later compromised.
The staffer's login credentials were stolen from the website by hackers, who used them to raid the worker's Dropbox locker. In there they found a document containing email addresses registered with Dropbox accounts. The company stated:
Our investigation found that usernames and passwords recently stolen from other websites were used to sign in to a small number of Dropbox accounts. We’ve contacted these users and have helped them protect their accounts.
A stolen password was also used to access an employee Dropbox account containing a project document with user email addresses. We believe this improper access is what led to the spam. We’re sorry about this, and have put additional controls in place to help make sure it doesn’t happen again.
Dropbox failed to say how many account records had been compromised, stating that its investigation remains ongoing. In the meantime it has promised to introduce tougher security controls such as optional two-factor authentication systems for logins, "new automated mechanisms to help identify suspicious activity" and systems to force users to retire passwords that are weak or haven't been changed in ages.
Experts, such as Rik Ferguson of Trend Micro, see shortcomings in Dropbox's handling of the affair, as explained in a blog post here. ®