Articles / SuSE: fetchmail remote priv…

SuSE: fetchmail remote privilege escalation

Fetchmail is a tool for retrieving and forwarding mail. Two vulnerabilities in the code of fetchmail were found in the last weeks. Both vulnerabilities could be used to get remote access to the system with the privilege of the user running fetchmail. Fixed RPMs can be obtained from ftp.suse.com.
-----BEGIN PGP SIGNED MESSAGE-----

______________________________________________________________________________

                        SuSE Security Announcement

        Package:                fetchmail
        Announcement-ID:        SuSE-SA:2001:026
        Date:                   Thursday, August 16th 2001 11:30 MEST
        Affected SuSE versions: [6.0, 6.1, 6.2,] 6.3, 6.4, 7.0, 7.1, 7.2
        Vulnerability Type:     remote privilege escalation
        Severity (1-10):        6
        SuSE default package:   yes
        Other affected systems: yes

        Content of this advisory:
        1) security vulnerability resolved: fetchmail
           problem description, discussion, solution and upgrade information
        2) pending vulnerabilities, solutions, workarounds
        3) standard appendix (further information)

______________________________________________________________________________

1)  problem description, brief discussion, solution, upgrade information

  Fetchmail is a tool for retrieving and forwarding mail. Two vulnerabilities
  in the code of fetchmail were found in the last weeks.
    1.) By sending a header with a large "To:" line a buffer overflow will
        be triggered in the header parsing code.
    2.) By impersonating a pop3 or imap server by using DNS spoofing
        or getting control over the pop3/imap server an attacker could
        trigger a buffer overflow in the pop3 and imap code of fetchmail.
        All the attacker has to do is to fake a LIST response message and
        providing two integers. One will used as index for a stack array
        and the other one is the value written to this index.
  Both vulnerabilities could be used to get remote access to the system with
  the privilege of the user running fetchmail.

  A temporary fix is not possible, so we suggest to install the new RPM
  on your system.



  i386 Intel Platform:

  SuSE-7.2
  ftp://ftp.suse.com/pub/suse/i386/update/7.2/n1/fetchmail-5.8.0-48.i386.rpm
      995660f54f997eb33120c6dcdab5ca73
  source rpm:
  ftp://ftp.suse.com/pub/suse/i386/update/7.2/zq1/fetchmail-5.8.0-48.src.rpm
      6466071439f694d89d011c35265de909

  SuSE-7.1
  ftp://ftp.suse.com/pub/suse/i386/update/7.1/n1/fetchmail-5.6.5-27.i386.rpm
      a6185bbbd1cdeb6f4b5a7afbe8efcd31
  SuSE-7.1
  ftp://ftp.suse.com/pub/suse/i386/update/7.1/n2/fetchmailconf-5.6.5-0.i386.rpm
      4ed63ae1652db9037c56e8a6bbf95da2
  source rpm:
  ftp://ftp.suse.com/pub/suse/i386/update/7.1/zq1/fetchmail-5.6.5-27.src.rpm
      27aed0c7fbfb882dce9451a1c673908d

  SuSE-7.0
  ftp://ftp.suse.com/pub/suse/i386/update/7.0/n1/fetchml-5.4.0-3.i386.rpm
      b2aec10ba865e37bef95a32f8adfa8d2
  source rpm:
  ftp://ftp.suse.com/pub/suse/i386/update/7.0/zq1/fetchml-5.4.0-3.src.rpm
      8a133db913032e2ea04517e0d86dde5c

  SuSE-6.4
  ftp://ftp.suse.com/pub/suse/i386/update/6.4/n1/fetchml-5.3.0-3.i386.rpm
      d8c0aed277da334a5be9d7241f2d3fc3
  source rpm:
  ftp://ftp.suse.com/pub/suse/i386/update/6.4/zq1/fetchml-5.3.0-3.src.rpm
      732deaa4ba6e181d15c8dbabff5e309f

  SuSE-6.3
  ftp://ftp.suse.com/pub/suse/i386/update/6.3/n1/fetchml-5.1.2-7.i386.rpm
      d0e91680594f84f161f8dfee95125e0a
  source rpm:
  ftp://ftp.suse.com/pub/suse/i386/update/6.3/zq1/fetchml-5.1.2-7.src.rpm
      cac94bd2373d75dad6c91d66583eadfb



  Sparc Platform:

  SuSE-7.1
  ftp://ftp.suse.com/pub/suse/sparc/update/7.1/n1/fetchmail-5.6.5-12.sparc.rpm
      4d7dcbf03a030ece4dd50acd3b330ad3
  source rpm:
  ftp://ftp.suse.com/pub/suse/sparc/update/7.1/zq1/fetchmail-5.6.5-12.src.rpm
      9d245f4358da492133e5a735497dbf2b

  SuSE-7.0
  ftp://ftp.suse.com/pub/suse/sparc/update/7.0/n1/fetchml-5.4.0-3.sparc.rpm
      07462524836665fb3ad8da365b948f5f
  source rpm:
  ftp://ftp.suse.com/pub/suse/sparc/update/7.0/zq1/fetchml-5.4.0-3.src.rpm
      bb2438d4e03b01415d675c2d05e3c847



  AXP Alpha Platform:

  SuSE-7.1
  ftp://ftp.suse.com/pub/suse/axp/update/7.1/n1/fetchmail-5.6.5-16.alpha.rpm
      0a4503aadd5981e9a4c2bc57a46eb9b9
  source rpm:
  ftp://ftp.suse.com/pub/suse/axp/update/7.1/zq1/fetchmail-5.6.5-16.src.rpm
      a8c6425a9f15b04ff27a4f0636e65f93

  SuSE-7.0
  ftp://ftp.suse.com/pub/suse/axp/update/7.0/n1/fetchml-5.4.0-3.alpha.rpm
      851a72a94dc9aa152fff3f9dfd30aeb5
  source rpm:
  ftp://ftp.suse.com/pub/suse/axp/update/7.0/zq1/fetchml-5.4.0-3.src.rpm
      e876b48882702c6c45e01326f85a610a

  SuSE-6.4
  ftp://ftp.suse.com/pub/suse/axp/update/6.4/n1/fetchml-5.3.0-3.alpha.rpm
      e44e632813710d4eb3b778414733631e
  source rpm:
  ftp://ftp.suse.com/pub/suse/axp/update/6.4/zq1/fetchml-5.3.0-3.src.rpm
      27908e4fe9995dd86054533d17e85f5b

  SuSE-6.3
  ftp://ftp.suse.com/pub/suse/axp/update/6.3/n1/fetchml-5.1.2-4.alpha.rpm
      0751d23ccdfd860409cb592b84c203e4
  source rpm:
  ftp://ftp.suse.com/pub/suse/axp/update/6.3/zq1/fetchml-5.1.2-4.src.rpm
      ac0a757562c01bf84780fd81e04a7784



  PPC PowerPC Platform:

  SuSE-7.1
    ftp://ftp.suse.com/pub/suse/ppc/update/7.1/n1/fetchmail-5.6.5-16.ppc.rpm
      f84f2b9f669e3ba65d42ddac78b9f49c
  source rpm:
  ftp://ftp.suse.com/pub/suse/ppc/update/7.1/zq1/fetchmail-5.6.5-16.src.rpm
      999b7fcfb1799ae98d5a2ffaf103f9a7

  SuSE-7.0
  ftp://ftp.suse.com/pub/suse/ppc/update/7.0/n1/fetchml-5.4.0-3.ppc.rpm
      55a46529b8f9cae39cd3a3d06728e300
  source rpm:
  ftp://ftp.suse.com/pub/suse/ppc/update/7.0/zq1/fetchml-5.4.0-3.src.rpm
      b3ecbc340fb46e5c6501f34184fa69fd

  SuSE-6.4
  ftp://ftp.suse.com/pub/suse/ppc/update/6.4/n1/fetchml-5.3.0-3.ppc.rpm
      d3bf46ca935d696b1a45ff1b3c820840
  source rpm:
  ftp://ftp.suse.com/pub/suse/ppc/update/6.4/zq1/fetchml-5.3.0-3.src.rpm
      6dbd73a017fd2915c9197860f47a6d28


______________________________________________________________________________

2)  Pending vulnerabilities in SuSE Distributions and Workarounds:

  Please watch out for upcomming announcements.


______________________________________________________________________________

3)  standard appendix: authenticity verification, additional information

  - Package authenticity verification:

    SuSE update packages are available on many mirror ftp servers all over
    the world. While this service is being considered valuable and important
    to the free and open source software community, many users wish to be
    sure about the origin of the package and its content before installing
    the package. There are two verification methods that can be used
    independently from each other to prove the authenticity of a downloaded
    file or rpm package:
    1) md5sums as provided in the (cryptographically signed) announcement.
    2) using the internal gpg signatures of the rpm package.

    1) execute the command
        md5sum 
       after you downloaded the file from a SuSE ftp server or its mirrors.
       Then, compare the resulting md5sum with the one that is listed in the
       announcement. Since the announcement containing the checksums is
       cryptographically signed (usually using the key security@suse.de),
       the checksums show proof of the authenticity of the package.
       We advise against subscribing to security lists which cause the
       email message containing the announcement to be modified so that
       the signature does not match after transport through the mailing
       list software.
       Downsides: You must be able to verify the authenticity of the
       announcement in the first place. If RPM packages are being rebuilt
       and a new version of a package is published on the ftp server, all
       md5 sums for the files are useless.

    2) rpm package signatures provide an easy way to verify the authenticity
       of an rpm package. Use the command
        rpm -v --checksig 
       to verify the signature of the package, where  is the
       filename of the rpm package that you have downloaded. Of course,
       package authenticity verification can only target an uninstalled rpm
       package file.
       Prerequisites:
        a) gpg is installed
        b) The package is signed using a certain key. The public part of this
           key must be installed by the gpg program in the directory
           ~/.gnupg/ under the user's home directory who performs the
           signature verification (usually root). You can import the key
           that is used by SuSE in rpm packages for SuSE Linux by saving
           this announcement to a file ("announcement.txt") and
           running the command (do "su -" to be root):
            gpg --batch; gpg < announcement.txt | gpg --import
           SuSE Linux distributions version 7.1 and thereafter install the
           key "build@suse.de" upon installation or upgrade, provided that
           the package gpg is installed. The file containing the public key
           is placed at the toplevel directory of the first CD (pubring.gpg)
           and at ftp://ftp.suse.com/pub/suse/pubring.gpg-build.suse.de .


  - SuSE runs two security mailing lists to which any interested party may
    subscribe:

    suse-security@suse.com
        -   general/linux/SuSE security discussion.
            All SuSE security announcements are sent to this list.
            To subscribe, send an email to
                .

    suse-security-announce@suse.com
        -   SuSE's announce-only mailing list.
            Only SuSE's security annoucements are sent to this list.
            To subscribe, send an email to
                .

    For general information or the frequently asked questions (faq)
    send mail to:
         or
         respectively.

    ===================================================
    SuSE's security contact is .
    The  public key is listed below.
    ===================================================
______________________________________________________________________________

    The information in this advisory may be distributed or reproduced,
    provided that the advisory is not modified in any way. In particular,
    it is desired that the cleartext signature shows proof of the
    authenticity of the text.
    SuSE GmbH makes no warranties of any kind whatsoever with respect
    to the information contained in this security advisory.

Type Bits/KeyID    Date       User ID
pub  2048R/3D25D3D9 1999-03-06 SuSE Security Team 
pub  1024D/9C800ACA 2000-10-19 SuSE Package Signing Key 

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Bye,
     Thomas
-- 
  Thomas Biege, SuSE GmbH, Schanzaeckerstr. 10, 90443 Nuernberg
  E@mail: thomas@suse.de      Function: Security Support & Auditing
  "lynx -source http://www.suse.de/~thomas/contact/thomas.asc | pgp -fka"
  Key fingerprint = 51 AD B9 C7 34 FC F2 54  01 4A 1C D4 66 64 09 84
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