Hundreds of alleged usernames and passwords of online document-sharing site Dropbox were published on Monday on Pastebin, an anonymous information-sharing website.
The anonymous user, who claims to have hacked close to 7 million accounts, is calling for Bitcoin donations to fund the operation.
"We will keep releasing more to the public as donations come in, show your support," the anonymous Pastebin user said on the site.
Dropbox, however, said it has not been hacked.
"These usernames and passwords were unfortunately stolen from other services and used in attempts to login to Dropbox accounts. We had previously detected these attacks and the vast majority of the passwords posted have been expired for some time now. All other remaining passwords have been expired as well," a Dropbox spokesman said in an email to Reuters.
NSA whistleblower Edward Snowden last week advised those concerned about their privacy to "get rid of Dropbox" and cease using Facebook and Google.
