(fwd) "Will You Be a Terrorist?"

[Richard Parratt]

cactus at bb.com wrote:

> In any case, perhaps a way around this can be found: what we may
> need is "stealth remailers," software that will behave as a remailer
> through non-obvious "security holes" with correct cooperation from
> software the original user runs.  
> 
> For example, hack sendmail so that it never wants to reverse-lookup DNS
> and given a particular set of commands (saying "EHDR" for 'enhanced
> headers') will operate as an anonymous remailer.  Such sendmail-hackage
> could be distributed with other changes that give enhanced security
> (for example, that turn off EXPN and VRFY) so that people could claim
> that they had no idea that they were operating an anonymous remailer.

When Sendmail gets a mail to an unknown user (e.g. nobody at grunt.com),
it will reject the mail. The relaying mailer is then supposed to bounce the
mail back to the author.

So if we forge the From: line, the mail should bounce back to the bogus
target. If I forge a mail as follows:
 From: cypherpunks at toad.com
 To: nobody_at_all at bb.com
 ------blah blah blah-----

It should bounce and thus appear on the cypherpunks list, without a sender.
Of course, it will have paths, etc, which give the game away. What is 
needed to give 'Stealth' remailing is a mailer that when seeing a header
such as 'X-Bounce-Strip: 1' removes headers and sends body text only back.
This is a useful feature to reduce network bandwidth when bouncing mail,
and should be included in all sendmails (grin).

--
Richard Parratt