On Monday, the OpenSSL project released an update to address a serious security vulnerability nicknamed "Heartbleed". This vulnerability impacts the encryption used for internet communications and could allow access to decrypted HTTPS traffic. Like many service providers, once Mandrill became aware of Heartbleed, we moved to address, and evaluate the impact of, this vulnerability. We know that our users share our concern for security and privacy, so we want you to be aware of the specifics of Heartbleed vulnerability as it relates to Mandrill.
First and foremost, we have no evidence that the Heartbleed vulnerability was used to obtain any Mandrill data or to access Mandrill services.
Mandrill's relay and application servers were using affected versions of OpenSSL. Patches have been applied to all impacted servers, a process which was completed and confirmed by 14:00 UTC on April 8th. Although Mandrill utilizes Amazon EC2, we don't use the disk images provided by Amazon that were found to be affected. Nevertheless as a precaution, we've replaced our private key and SSL certificate since it's plausible that Mandrill's certificates could have been exposed.
What you should do
While there's no indication that Mandrill user data has been impacted, we strongly recommend that users update their Mandrill account passwords. Since API Keys are used for accessing your account via the API and SMTP, we also recommend deactivating old keys and replacing them with new keys.
Many of our users have sites or applications hosted which store their Mandrill credentials or other sensitive data. So, we also recommend auditing all services you may use to determine if they are also vulnerable, taking steps to repair any vulnerable services, and replacing SSL certificates once the vulnerability has been removed.