Synopsis

Critical: krb5 security update

Type/Severity

Security Advisory: Critical

Topic

Updated krb5 packages that fix one security issue are now available for
Red Hat Enterprise Linux 4 and 5.

The Red Hat Security Response Team has rated this update as having Critical
security impact. A Common Vulnerability Scoring System (CVSS) base score,
which gives a detailed severity rating, is available from the CVE link in
the References section.

Description

Kerberos is a network authentication system which allows clients and servers
to authenticate to each other using symmetric encryption and a trusted third-
party, the Key Distribution Center (KDC).

A buffer overflow flaw was found in the MIT krb5 telnet daemon (telnetd). A
remote attacker who can access the telnet port of a target machine could use
this flaw to execute arbitrary code as root. (CVE-2011-4862)

Note that the krb5 telnet daemon is not enabled by default in any version of
Red Hat Enterprise Linux. In addition, the default firewall rules block
remote access to the telnet port. This flaw does not affect the telnet
daemon distributed in the telnet-server package.

For users who have installed the krb5-workstation package, have enabled the
telnet daemon, and have it accessible remotely, this update should be
applied immediately.

All krb5-workstation users should upgrade to these updated packages, which
contain a backported patch to correct this issue.

Solution

The krb5 telnet daemon is an xinetd service. You can determine if krb5
telnetd is enabled with the commands:

/sbin/chkconfig --list krb5-telnet
/sbin/chkconfig --list ekrb5-telnet

The output of these commands will display "on" if krb5 telnet is enabled.
krb5 telnet daemon can be immediately disabled with the commands:

/sbin/chkconfig krb5-telnet off
/sbin/chkconfig ekrb5-telnet off

Before applying this update, make sure all previously-released errata
relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at
https://access.redhat.com/kb/docs/DOC-11259

Affected Products

• Red Hat Enterprise Linux Server 5 x86_64
• Red Hat Enterprise Linux Server 5 ia64
• Red Hat Enterprise Linux Server 5 i386
• Red Hat Enterprise Linux Server 4 x86_64
• Red Hat Enterprise Linux Server 4 ia64
• Red Hat Enterprise Linux Server 4 i386
• Red Hat Enterprise Linux Workstation 5 x86_64
• Red Hat Enterprise Linux Workstation 5 i386
• Red Hat Enterprise Linux Workstation 4 x86_64
• Red Hat Enterprise Linux Workstation 4 ia64
• Red Hat Enterprise Linux Workstation 4 i386
• Red Hat Enterprise Linux Desktop 5 x86_64
• Red Hat Enterprise Linux Desktop 5 i386
• Red Hat Enterprise Linux Desktop 4 x86_64
• Red Hat Enterprise Linux Desktop 4 i386
• Red Hat Enterprise Linux for IBM z Systems 5 s390x
• Red Hat Enterprise Linux for IBM z Systems 4 s390x
• Red Hat Enterprise Linux for IBM z Systems 4 s390
• Red Hat Enterprise Linux for Power, big endian 5 ppc
• Red Hat Enterprise Linux for Power, big endian 4 ppc
• Red Hat Enterprise Linux Server from RHUI 5 x86_64
• Red Hat Enterprise Linux Server from RHUI 5 i386

Fixes

• BZ - 770325 - CVE-2011-4862 krb5-appl: remote buffer overflow in kerberised telnet daemon

CVEs

• CVE-2011-4862

References

• https://access.redhat.com/security/updates/classification/#critical
• http://web.mit.edu/kerberos/advisories/MITKRB5-SA-2011-008.txt

Red Hat Enterprise Linux Server 5

SRPM
x86_64
krb5-devel-1.6.1-63.el5_7.i386.rpm	SHA-256: 73b410e20f1a7e714b287ddd481bb772e08ae26a21ea4a625c090b36b3a3607d
krb5-devel-1.6.1-63.el5_7.x86_64.rpm	SHA-256: 8b0ed4f9474f118bc4029583637100e16fb75fade5c4a89c1d9b2dfad148d496
krb5-server-1.6.1-63.el5_7.x86_64.rpm	SHA-256: 58dfa2756e241e80ba9ec9d1781d3e932c6723dc88131c935099342863252bd8
krb5-server-ldap-1.6.1-63.el5_7.x86_64.rpm	SHA-256: 54e20d84d794caa1f51651d709dfa5e538580c9d41d3942a7f3ea6514a67e0b3
i386
krb5-devel-1.6.1-63.el5_7.i386.rpm	SHA-256: 73b410e20f1a7e714b287ddd481bb772e08ae26a21ea4a625c090b36b3a3607d

Red Hat Enterprise Linux Workstation 5

SRPM
x86_64
krb5-devel-1.6.1-63.el5_7.i386.rpm	SHA-256: 73b410e20f1a7e714b287ddd481bb772e08ae26a21ea4a625c090b36b3a3607d
krb5-devel-1.6.1-63.el5_7.x86_64.rpm	SHA-256: 8b0ed4f9474f118bc4029583637100e16fb75fade5c4a89c1d9b2dfad148d496
krb5-server-1.6.1-63.el5_7.x86_64.rpm	SHA-256: 58dfa2756e241e80ba9ec9d1781d3e932c6723dc88131c935099342863252bd8
krb5-server-ldap-1.6.1-63.el5_7.x86_64.rpm	SHA-256: 54e20d84d794caa1f51651d709dfa5e538580c9d41d3942a7f3ea6514a67e0b3
i386
krb5-devel-1.6.1-63.el5_7.i386.rpm	SHA-256: 73b410e20f1a7e714b287ddd481bb772e08ae26a21ea4a625c090b36b3a3607d

Red Hat Enterprise Linux Server from RHUI 5

SRPM
x86_64
krb5-devel-1.6.1-63.el5_7.i386.rpm	SHA-256: 73b410e20f1a7e714b287ddd481bb772e08ae26a21ea4a625c090b36b3a3607d
krb5-devel-1.6.1-63.el5_7.x86_64.rpm	SHA-256: 8b0ed4f9474f118bc4029583637100e16fb75fade5c4a89c1d9b2dfad148d496
krb5-server-1.6.1-63.el5_7.x86_64.rpm	SHA-256: 58dfa2756e241e80ba9ec9d1781d3e932c6723dc88131c935099342863252bd8
krb5-server-ldap-1.6.1-63.el5_7.x86_64.rpm	SHA-256: 54e20d84d794caa1f51651d709dfa5e538580c9d41d3942a7f3ea6514a67e0b3
i386
krb5-devel-1.6.1-63.el5_7.i386.rpm	SHA-256: 73b410e20f1a7e714b287ddd481bb772e08ae26a21ea4a625c090b36b3a3607d