Re: Procmail feature security hole?

[Frank T. <ft...@ui...>]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Billy Donahue, at 00:55 -0400 on Tue, 3 Oct 2000, wrote:

> If I send this forged message to someone using the procmail script,
> They will have no indication that it wasn't really decrypted by pgpenvelope
> (other than the fact that it doesn't show up in the pgpenvelope-backup folder).
> The forged message will look like pgpenvelope verified it.

I've thought about this issue, and haven't come with a good way to solve
it yet.  I could escape the lines if they match

- -----pgpenvelope processed message-----

But, what if it's:

- ----pgpenvelope procesed message-----

(notice, processed is spelled wrong).  Your ordinary user is not going to
notice this, and neither will the script.  One additional thing I could do
is to add a:

pgpenvelope_decrypt: Message decrypted by <user> on <hostname>

...when the message is decrypted, so this could help if the message is
sent to multiple people; if this statement was inserted, then it would
hold true for only one user the attacker targeted.

Actually, the best solution, which just came to mind, is for each user to
define their own:

#top-border          = -----pgpenvelope processed message-----
#info-top-border     = -----pgpenvelope information-----
#info-bottom-Border  = -----end pgpenvelope information-----

to maybe something like:

#top-border          = -----stuff checked by pgpenvelope-----
#info-top-border     = -----pgpenvelope says-----
#info-bottom-Border  = -----pgpenvelope is done-----

If the user defines this to something non-standard, and the attacker
doesn't know them, then the user will notice that the message doesn't have
his 'personalized' headers.

> By the way, I believe that as of Oct 1, 2000, 'digital signatures'
> (whatever that means) are legally binding.

Actually, I think it's 'electronic signatures', which are just electronic
renderings of your handwritten signature.

- -- 
Frank Tobin		http://www.uiuc.edu/~ftobin/




-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.0.3 (FreeBSD)
Comment: pgpenvelope 2.9.0 - http://pgpenvelope.sourceforge.net/

iEYEARECAAYFAjnZeUwACgkQVv/RCiYMT6POpgCeKBhDYezsfMeoaYxTDiiachVq
L4oAn1tye+kpqqEZyaXF0P6yFw/lGYwZ
=L8SE
-----END PGP SIGNATURE-----