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Mozilla Mistakenly Posts File Containing Registered User Data

Mozilla Mistakenly Posts File Containing Registered User Data, Including MD5 Hash Passwords, to Public Web Server

Mozilla Mistakenly Posts File Containing Registered User DataMozilla today alerted registered users of its site that it had mistakenly posted a file to a publicly available Web server which contained data from its registered user database including email addresses, first and last names, and an md5 hash representation of user passwords.

The site hosts add-ons to Mozilla software, such as Firefox, Thunderbird, SeaMonkey, and Sunbird which let users add new features and change the way browsers or applications work.

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The organization claims it was notified by a third party who discovered the file on December 17th via its Web bounty program, and after investigating, does not believe the file was downloaded by others outside of Mozilla and the third party who reported the file to Mozilla. In response, Mozilla deleted all user passwords and has asked users to reset their passwords manually and change the password to any other sites which may utilize the same password. 

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Update: Chris Lyon, Director of Infrastructure Security at Mozilla, shared some additional information via blog post late Monday night (after we published this initial report) and noted that "The database included 44,000 inactive accounts using older, md5-based password hashes. We erased all the md5-passwords, rendering the accounts disabled. All current accounts use a more secure SHA-512 password hash with per-user salts. SHA-512 and per user salts has been the standard storage method of password hashes for all active users since April 9th, 2009."

A copy of the email which Lyon sent to on Monday evening is below:

Dear user,

The purpose of this email is to notify you about a possible disclosure of your information which occurred on December 17th. On this date, we were informed by a 3rd party who discovered a file with individual user records on a public portion of one of our servers. We immediately took the file off the server and investigated all downloads. We have identified all the downloads and with the exception of the 3rd party, who reported this issue, the file has been download by only Mozilla staff. This file was placed on this server by mistake and was a partial representation of the users database from The file included email addresses, first and last names, and an md5 hash representation of your password. The reason we are disclosing this event is because we have removed your existing password from the addons site and are asking you to reset it by going back to the addons site and clicking forgot password. We are also asking you to change your password on other sites in which you use the same password. Since we have effectively erased your password, you don't need to do anything if you do not want to use your account. It is disabled until you perform the password recovery.

We have identified the process which allowed this file to be posted publicly and have taken steps to prevent this in the future. We are also evaluating other processes to ensure your information is safe and secure.

Should you have any questions, please feel free to contact the infrastructure security team directly at [email protected]. If you are having issues resetting your account, please contact [email protected]. We apologize for any inconvenience this has caused.

Chris Lyon

Director of Infrastructure Security

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For more than 10 years, Mike Lennon has been closely monitoring the threat landscape and analyzing trends in the National Security and enterprise cybersecurity space. In his role at SecurityWeek, he oversees the editorial direction of the publication and is the Director of several leading security industry conferences around the world.