This week’s bug of the month is the trendily-named EFAIL.
Like many groovy bugs these days, it’s both a BWAIN (bug with an impressive name) and a BWIVOL (bug with its very own logo, shown in the image at the top of this article).
The name is a pun of sorts on the word “email”, and the bug is caused by a flaw in the specifications set down for two popular standards used for email encryption, namely OpenPGP and S/MIME.
Simply put, the EFAIL vulnerabilities are a pair of security holes that a crook might be able to use to trick recipients of encrypted messages into leaking out some or all of their decrypted content.
Note that this attack only applies if you are using S/MIME or OpenPGP for end-to-end email encryption.
If you aren’t using either of these add-ons in your email client, this vulnerability doesn’t affect you – after all, if the crooks can sniff out your original messages and they’re not encrypted, they’ve got your plaintext already.
Note also that this attack doesn’t work on all messages; it doesn’t work in real time; you need a copy of the original encrypted message; it only works with some email clients; and it pretty much requires both HTML rendering and remote content download turned on in your email client.