Debian: 'nullmailer' Denial of Service
Posted by LinuxSecurity.com Team   
Debian When a mail is to be delivered locally to a user that doesn'texist, nullmailer tries to deliver it, discovers a user unknown errorand stops delivering. Unfortunately, it stops delivering entirely,not only this mail.

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Debian Security Advisory DSA 198-1                     security@debian.org 
http://www.debian.org/security/                             Martin Schulze
November 18th, 2002                      http://www.debian.org/security/faq
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Package        : nullmailer
Vulnerability  : denial of service
Problem-type   : local
Debian-specific: no

A problem has been discovered in nullmailer, a simple relay-only mail
transport agent for hosts that relay mail to a fixed set of smart
relays.  When a mail is to be delivered locally to a user that doesn't
exist, nullmailer tries to deliver it, discovers a user unknown error
and stops delivering.  Unfortunately, it stops delivering entirely,
not only this mail.  Hence, it's very easy to craft a denial of service.

This problem has been fixed in version 1.00RC5-16.1woody2 for the
current stable distribution (woody) and in version 1.00RC5-17 for the
unstable distribution (sid).  The old stable distribution (potato)
does not contain a nullmailer package.

We recommend that you upgrade your nullmailer package.

wget url
        will fetch the file for you
dpkg -i file.deb
        will install the referenced file.

If you are using the apt-get package manager, use the line for
sources.list as given below:

apt-get update
        will update the internal database
apt-get upgrade
        will install corrected packages

You may use an automated update by adding the resources from the
footer to the proper configuration.


Debian GNU/Linux 3.0 alias woody
--------------------------------

  Source archives:

     http://security.debian.org/pool/updates/main/n/nullmailer/nullmailer_1.00RC5-16.1woody2.dsc
      Size/MD5 checksum:      602 39d11580de5a781c1cadf6d422164d8c
     http://security.debian.org/pool/updates/main/n/nullmailer/nullmailer_1.00RC5-16.1woody2.diff.gz
      Size/MD5 checksum:     6298 179e56c04af207b19ff020f66b580419
     http://security.debian.org/pool/updates/main/n/nullmailer/nullmailer_1.00RC5.orig.tar.gz
      Size/MD5 checksum:   111691 61041ff5b1e41f9280d63a04c3383144

  Alpha architecture:

     http://security.debian.org/pool/updates/main/n/nullmailer/nullmailer_1.00RC5-16.1woody2_alpha.deb
      Size/MD5 checksum:   103944 e46443575ae0a0d55475423b1e31bdeb

  ARM architecture:

     http://security.debian.org/pool/updates/main/n/nullmailer/nullmailer_1.00RC5-16.1woody2_arm.deb
      Size/MD5 checksum:    70804 2feab48d3941330c03f00567488831f5

  Intel IA-32 architecture:

     http://security.debian.org/pool/updates/main/n/nullmailer/nullmailer_1.00RC5-16.1woody2_i386.deb
      Size/MD5 checksum:    68558 ec8e1b3f33bc436897358c80a6f43b3c

  Intel IA-64 architecture:

     http://security.debian.org/pool/updates/main/n/nullmailer/nullmailer_1.00RC5-16.1woody2_ia64.deb
      Size/MD5 checksum:   144246 c508c104d7b775e84641aabdc2adf209

  HP Precision architecture:

     http://security.debian.org/pool/updates/main/n/nullmailer/nullmailer_1.00RC5-16.1woody2_hppa.deb
      Size/MD5 checksum:    88306 87b75f52b7ae1e8bdab2a121b79492bd

  Motorola 680x0 architecture:

     http://security.debian.org/pool/updates/main/n/nullmailer/nullmailer_1.00RC5-16.1woody2_m68k.deb
      Size/MD5 checksum:    67616 29f83614261e229bff40b1c54b12fa3b

  Big endian MIPS architecture:

     http://security.debian.org/pool/updates/main/n/nullmailer/nullmailer_1.00RC5-16.1woody2_mips.deb
      Size/MD5 checksum:   102682 91e6a2aabc65fb2b430619dc625a6485

  Little endian MIPS architecture:

     http://security.debian.org/pool/updates/main/n/nullmailer/nullmailer_1.00RC5-16.1woody2_mipsel.deb
      Size/MD5 checksum:   101292 83745fe1ea40cdefb298e2d55f1e0a2b

  PowerPC architecture:

     http://security.debian.org/pool/updates/main/n/nullmailer/nullmailer_1.00RC5-16.1woody2_powerpc.deb
      Size/MD5 checksum:    73996 81bbf1beb5a46a08405d1e4535b4ae44

  IBM S/390 architecture:

     http://security.debian.org/pool/updates/main/n/nullmailer/nullmailer_1.00RC5-16.1woody2_s390.deb
      Size/MD5 checksum:    72914 3e5608138030d4577e14e0f17144a2ff

  Sun Sparc architecture:

     http://security.debian.org/pool/updates/main/n/nullmailer/nullmailer_1.00RC5-16.1woody2_sparc.deb
      Size/MD5 checksum:    73748 cb947e14ce9c2803d55f959d4f03f454


  These files will probably be moved into the stable distribution on
  its next revision.

Survey on the use of Debian GNU/Linux 2.2 alias potato: 
http://lists.debian.org/debian-devel-announce-0211/msg00001.html

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For apt-get: deb  http://security.debian.org/ stable/updates main
For dpkg-ftp:  ftp://security.debian.org/debian-security dists/stable/updates/main
Mailing list: debian-security-announce@lists.debian.org
Package info: `apt-cache show ' and  http://packages.debian.org/