Synopsis

Critical: krb5-appl security update

Type/Severity

Security Advisory: Critical

Topic

Updated krb5-appl packages that fix one security issue are now available
for Red Hat Enterprise Linux 6.0 and 6.1 Extended Update Support.

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

The krb5-appl packages provide Kerberos-aware telnet, ftp, rcp, rsh, and
rlogin clients and servers. 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-appl-servers package, have enabled
the krb5 telnet daemon, and have it accessible remotely, this update should
be applied immediately.

All krb5-appl-server 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 command 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 - Extended Update Support 6.1 x86_64
• Red Hat Enterprise Linux Server - Extended Update Support 6.1 i386
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 6.1 s390x
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.1 ppc64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.1 x86_64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.1 i386
• Red Hat Virtual Storage Appliance (from RHUI) 6.1 x86_64

Fixes

• BZ - 770325 - CVE-2011-4862 krb5: remote buffer overflow in kerberized 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 - Extended Update Support 6.1

SRPM
krb5-appl-1.0.1-2.el6_1.3.src.rpm	SHA-256: a2b11cc31d5b1ae1cbd4028977a15838ef37996716df54a37e8666ec6491c351
x86_64
krb5-appl-clients-1.0.1-2.el6_1.3.x86_64.rpm	SHA-256: 2ffcaf2291463005d3ac66ae083715769a7af7a8309e4ef56261fc54fca90310
krb5-appl-debuginfo-1.0.1-2.el6_1.3.x86_64.rpm	SHA-256: 30d9145167e07b916da169c2edfa09265ec527a03d707e53e3745da0cdbdcafc
krb5-appl-servers-1.0.1-2.el6_1.3.x86_64.rpm	SHA-256: 00946b89f9d217fe57b2295adb5843294a38125fbb7718ed75a5e59e5432ff15
i386
krb5-appl-clients-1.0.1-2.el6_1.3.i686.rpm	SHA-256: f194fb6ec311ed07806a7f5cddfd913d638bfcea629362376344e7fc53284b00
krb5-appl-debuginfo-1.0.1-2.el6_1.3.i686.rpm	SHA-256: 88d4e8ff713ef00828f2512dadcf245e7645f58aca4c02dd739131ee04cad4fc
krb5-appl-servers-1.0.1-2.el6_1.3.i686.rpm	SHA-256: f1d33134f04200243d100f152eb9f9674a636957f5b153fe758faf57a396a5c4

Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 6.1

SRPM
s390x
krb5-appl-clients-1.0.1-2.el6_1.3.s390x.rpm	SHA-256: 16105b00f50eda15f287c364fad13f325b7182fe5e7001b71f380fe3dc1db901
krb5-appl-debuginfo-1.0.1-2.el6_1.3.s390x.rpm	SHA-256: 34ce77855d5c9666e6294b8cec6ef4f7a0cf8fda998f7faf043db04136bd3452
krb5-appl-servers-1.0.1-2.el6_1.3.s390x.rpm	SHA-256: 6360b508546db5da85eaf3d92baa80c1015042649ab8abea9caf59707417fa94

Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.1

SRPM
ppc64
krb5-appl-clients-1.0.1-2.el6_1.3.ppc64.rpm	SHA-256: 937777bf356a069ed228221ae0833a7c112a33709d549fcaa5b0ec6cb43b4b5c
krb5-appl-debuginfo-1.0.1-2.el6_1.3.ppc64.rpm	SHA-256: 7207301b976c3bebe672c1af3ea806d3293cf3c5bd828bbf43f0b7439cf3516a
krb5-appl-servers-1.0.1-2.el6_1.3.ppc64.rpm	SHA-256: f06203198b6af168a0e18d38a7d3f35c70a137219560cf2b63fe84b477483e50

Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.1

SRPM
krb5-appl-1.0.1-2.el6_1.3.src.rpm	SHA-256: a2b11cc31d5b1ae1cbd4028977a15838ef37996716df54a37e8666ec6491c351
x86_64
krb5-appl-clients-1.0.1-2.el6_1.3.x86_64.rpm	SHA-256: 2ffcaf2291463005d3ac66ae083715769a7af7a8309e4ef56261fc54fca90310
krb5-appl-debuginfo-1.0.1-2.el6_1.3.x86_64.rpm	SHA-256: 30d9145167e07b916da169c2edfa09265ec527a03d707e53e3745da0cdbdcafc
krb5-appl-servers-1.0.1-2.el6_1.3.x86_64.rpm	SHA-256: 00946b89f9d217fe57b2295adb5843294a38125fbb7718ed75a5e59e5432ff15
i386
krb5-appl-clients-1.0.1-2.el6_1.3.i686.rpm	SHA-256: f194fb6ec311ed07806a7f5cddfd913d638bfcea629362376344e7fc53284b00
krb5-appl-debuginfo-1.0.1-2.el6_1.3.i686.rpm	SHA-256: 88d4e8ff713ef00828f2512dadcf245e7645f58aca4c02dd739131ee04cad4fc
krb5-appl-servers-1.0.1-2.el6_1.3.i686.rpm	SHA-256: f1d33134f04200243d100f152eb9f9674a636957f5b153fe758faf57a396a5c4