Efail and Mutt

[Vincent Lefevre]

About Efail <https://efail.de/>, you may be interested in this
discussion:

https://lists.gnupg.org/pipermail/gnupg-users/2018-May/060315.html

Mutt is probably safe as not rendering HTML, but this isn't clear...
And piping a decrypted mail to a browser (e.g. if there is no
text/plain part, and an attacker can ensure that) is not safe.

Does it handle the GPG warning in a special way? The display of the
warning only is not sufficient since it can easily remain unnoticed
by the user.

[Kevin J. McCarthy]

Post by Vincent Lefevre
About Efail <https://efail.de/>, you may be interested in this
https://lists.gnupg.org/pipermail/gnupg-users/2018-May/060315.html
Mutt is probably safe as not rendering HTML, but this isn't clear...

The EFAIL team contacted Mutt in advance of their publication, politely
and well in advance.

At first it seemed we might have an S/MIME issue, but their subsequent
testing found we were (mostly) okay. The only issue was that checking
the certificate chain could notify someone the email had been opened. I
think this can be mitigated by using the "# Section D: Alternatives"
commands in contrib/smime.rc, but that cure may be worse than the
problem.

Post by Vincent Lefevre
And piping a decrypted mail to a browser (e.g. if there is no
text/plain part, and an attacker can ensure that) is not safe.
Does it handle the GPG warning in a special way? The display of the
warning only is not sufficient since it can easily remain unnoticed
by the user.

I added $pgp_decryption_okay in 1.6.0, which (when set to the defaults
in contrib/gpg.rc) checks for "[GNUPG:] DECRYPTION_OKAY" output. If
that's not there, the email is considered unsuccessfully decrypted.

[Eike Rathke]

Hi,

Post by Vincent Lefevre
And piping a decrypted mail to a browser (e.g. if there is no
text/plain part, and an attacker can ensure that) is not safe.

There's nothing wrong with a ~/.mailcap entry similar to this:

text/html; /usr/bin/elinks -localhost 1 -no-connect 1 -force-html -dump '%s'; copiousoutput


Eike