Gpg4Win. It does not cover S/MIME.) 2/
Breaking S/MIME and OpenPGP Encryption using Exfiltration Channels".
The EFF has gone so far as to recommend immediately uninstalling
Enigmail. We have three things to say, and then we're going to show you
1. This paper is misnamed.
2. This attack targets buggy email clients.
3. The authors made a list of buggy email clients.
feedback) had a weakness: in some cases an attacker could modify text.
As Werner Koch, the founder of GnuPG, put it: "[Phil Zimmermann] and Jon
Callas asked me to attend the AES conference in Rome to 5/
Code, or MDC. It's been a standard part of GnuPG for almost eighteen
years. For almost all that time, any message which does not have an MDC
attached has caused GnuPG to throw up big, clear, and obvious 7/
[long GnuPG output snipped for brevity -- see my prior tweet for a sample screenshot]
has been modified. In both cases, if your email client respects this
warning and does the right thing -- namely, not showing you the email --
then you are completely protected from the Efail attack, as 9/
If you're worried about the Efail attack, upgrade to the latest version
of GnuPG and check with your email plugin vendor to see if they handle
MDC errors correctly. Most do. 10/
We made three statements about the Efail attack at the beginning. We're
going to repeat them here and give a little explanation. Now that we've
explained the situation, we're confident you'll concur in 12/
1. This paper is misnamed. It's not an attack on OpenPGP. It's an
attack on broken email clients that ignore GnuPG's warnings and do silly
things after being warned. 13/
completely prevents this attack. GnuPG has had MDC support since the
summer of 2000. 14/
over their list of email clients (found at the very end) to see if yours
is vulnerable. But be careful, because it may not be accurate -- for
example, Mailpile says they're not vulnerable, but the paper 15/
The authors have done the community a good service by cataloguing buggy
email email clients. We're grateful to them for that. 16/