VNC rand() generates weak cookies

vnc-rand-weak-cookie (11384) The risk level is classified as MediumMedium Risk

Description:

The server wrapper in VNC versions prior to 3.3.3r2-21 uses the rand() function, instead of the srand() function, which causes the server to generate weaker than expected cookies. A remote attacker could use this vulnerability to guess a user's authentication cookie and gain unauthorized access to the system.


Consequences:

Configuration

Remedy:

Upgrade to the latest version of VNC (3.3.6 or later), available from the VNC Web page. See References.

For Red Hat Linux:
Upgrade to the latest vnc package, as listed below. Refer to RHSA-2003:041-15 for more information. See References.

Red Hat 7.0, 7.1, and 7.2: 3.3.3r2-18.6 or later
Red Hat 7.1 for iSeries and pSeries: 3.3r2-18.6.0p or later
Red Hat 7.3: 3.3.3r2-28.2. or later
Red Hat 8.0: 3.3.3r2-39.2 or later

For Gentoo Linux containing the tighevnc package:
Upgrade to the latest version of tightvnc(1.2.8 or later), as listed in Gentoo Linux Security Announcement 200302-15. See References.

For Gentoo Linux containing the net-misc/vnc package:
Upgrade to the latest version of vnc (3.3.6-r1 or later), as listed in Gentoo Linux Security Announcement 200302-16. See References.

For Mandrake Linux:
Upgrade to the latest vnc package, as listed below. Refer to MandrakeSoft Security Advisory MDKSA-2003:022:vnc for more information. See References.

Mandrake Linux 7.2: 3.3.3-8.4mdk or later
Mandrake Linux 8.0, 8.1, and 8.2: 3.3.3r2-9.3mdk or later
Mandrake Linux 9.0: 1.2.5-2.3mdk or later

For Conectiva Linux:
Upgrade to the latest vnc package, as listed below. Refer to Conectiva Linux Security Announcement CLSA-2003:640 for more information. See References.

Conectiva Linux 7.0: 3.3.3-6U70_2cl or later
Conectiva Linux 8.0: 3.3.3r2+tight1.2.2-6U80_1cl or later

For Sun Linux 5.0:
Apply the appropriate patches when they become available, as listed in Sun Alert ID: 56161. See References.

For other distributions:
Contact your vendor for upgrade or patch information.

References:

Platforms Affected:

  • AT&T VNC prior to 3.3.3r2-21
  • Conectiva Linux 7.0
  • Conectiva Linux 8.0
  • Gentoo Linux
  • MandrakeSoft Mandrake Linux 7.2
  • MandrakeSoft Mandrake Linux 8.0
  • MandrakeSoft Mandrake Linux 8.0 PPC
  • MandrakeSoft Mandrake Linux 8.1
  • MandrakeSoft Mandrake Linux 8.2
  • MandrakeSoft Mandrake Linux 8.2 PPC
  • MandrakeSoft Mandrake Linux 9.0
  • RedHat Enterprise Linux 2.1 AS
  • RedHat Linux 7
  • RedHat Linux 7.1
  • RedHat Linux 7.1 for iSeries
  • RedHat Linux 7.1 for pSeries
  • RedHat Linux 7.2
  • RedHat Linux 7.3
  • RedHat Linux 8.0
  • Sun Linux 5.0

Reported:

Oct 11, 2002

The information within this database may change without notice. Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. In no event shall the author/distributor (IBM Internet Security Systems X-Force) be held liable for any damages whatsoever arising out of or in connection with the use or spread of this information.

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