[neomutt-devel] Message security; protected header fields

[Kurt Hackenberg]

On Thu, Apr 18, 2024 at 06:37:50PM +0200, Alejandro Colomar wrote:

>I reported around a month ago a couple of security vulnerabilities to
>neomutt(1), but which are also present in mutt(1) and every MUA

So the main security vulnerability is that a recipient can tamper with 
header fields, and then reuse the message in some way, perhaps resend 
it?  And you propose to cryptographically sign certain headers to 
detect tampering?

Signing header fields sounds reasonable, but I don't entirely like an 
implementation that puts a copy of them in the message body, to be 
covered by GPG.  I'd prefer something more direct, that signs headers 
without copying them or modifying the message body.

DKIM already exists, and signs header fields.  It publishes a key 
through DNS, and so is used by the administrator of the sending domain 
rather than by the end user.  Is that acceptable?

Email authentication: <https://en.wikipedia.org/wiki/Email_authentication>

DKIM: <https://en.wikipedia.org/wiki/DomainKeys_Identified_Mail>