Today, MEGA has released software updates that fix a critical vulnerability reported by researchers at one of Europe’s leading universities, ETH Zurich, Switzerland. Further updates addressing less severe identified issues will follow in the near future. MEGA is not aware of any user accounts being compromised by these vulnerabilities.
Customers who have logged into their MEGA account at least 512 times (the more, the higher the exposure). Note that resuming an existing session does not count as a login. While all MEGA client products use permanent sessions by default, some third-party clients such as Rclone do not, so their users may be exposed.
Very few: An attacker would have had to first gain control over the heart of MEGA’s server infrastructure or achieve a successful man-in-the-middle attack on the user’s TLS connection to MEGA.
Once a targeted account had made enough successful logins, incoming shared folders, MEGAdrop files and chats could have been decryptable. Files in the cloud drive could have been successively decrypted during subsequent logins. Furthermore, files could have been placed in the account that appear to have been uploaded by the account holder (a “framing” attack).