Dropbox's file storage service was used for a tricky phishing attack, although the service was quick to shut down it down, according to Symantec.
The security vendor said it detected a batch of phishing emails advising recipients that they've been sent a large file and included a link to Dropbox-hosted page.
"The email claims the document can be viewed by clicking on the link included in the message," wrote Nick Johnston of Symantec in a blog post. "However, the link opens a fake Dropbox login page, hosted on Dropbox itself."
By hosting the fake login page on Dropbox, the scammers gain some benefits over hosting it on a random, strange-looking domain name. The phishing page is contained within Dropbox's user content domain, similar to shared photos or files, Johnston wrote.
Most of the phishing page's elements are also served over SSL (Secure Sockets Layer), which encrypts communication between a client and a server and makes the ruse look more convincing. Older browsers may not prompt a warning if SSL isn't used for the entire page, he wrote.
"The prominence of the warning varies from browser to browser; some browsers simply change the padlock symbol shown in the address bar, whereas others include a small banner at the top of the page," Johnston wrote. "Users may not notice or understand these security warnings or the associated implications."
Phishing attacks have often been staged on trusted domains for file storage and sharing, such as on Google's Docs and Drive services.
The phishing page, which was quickly taken down by Dropbox, asks for a user's Dropbox credentials but also includes logos for popular webmail services. It purports to allow people to use the same webmail credentials to log into Dropbox.
Once a set of credentials has been collected, a PHP script within phishing page simply redirects to Dropbox's actual login page, Johnston wrote.
Send news tips and comments to email@example.com. Follow me on Twitter: @jeremy_kirk