7.5 - RHSA-2005:562

Problem Description:

Updated krb5 packages which fix multiple security issues are now available for Red Hat Enterprise Linux 2.1 and 3.

This update has been rated as having critical security impact by the Red Hat Security Response Team.

2. Relevant releases/architectures:

Red Hat Enterprise Linux AS (Advanced Server) version 2.1 - i386, ia64 Red Hat Linux Advanced Workstation 2.1 - ia64 Red Hat Enterprise Linux ES version 2.1 - i386 Red Hat Enterprise Linux WS version 2.1 - i386 Red Hat Enterprise Linux AS version 3 - i386, ia64, ppc, s390, s390x, x86_64 Red Hat Desktop version 3 - i386, x86_64 Red Hat Enterprise Linux ES version 3 - i386, ia64, x86_64 Red Hat Enterprise Linux WS version 3 - i386, ia64, x86_64

3. Problem description:

Kerberos is a networked authentication system which uses a trusted third party (a KDC) to authenticate clients and servers to each other.

A double-free flaw was found in the krb5_recvauth() routine which may be triggered by a remote unauthenticated attacker. Although no exploit is currently known to exist, this issue could potentially be exploited to allow arbitrary code execution on a Key Distribution Center (KDC). The Common Vulnerabilities and Exposures project assigned the name CAN-2005-1689 to this issue.

Daniel Wachdorf discovered a single byte heap overflow in the krb5_unparse_name() function, part of krb5-libs. Sucessful exploitation of this flaw would lead to a denial of service (crash). To trigger this flaw an attacker would need to have control of a kerberos realm that shares a cross-realm key with the target, making exploitation of this flaw unlikely. (CAN-2005-1175).

Gaël Delalleau discovered an information disclosure issue in the way some telnet clients handle messages from a server. An attacker could construct a malicious telnet server that collects information from the environment of any victim who connects to it using the Kerberos-aware telnet client (CAN-2005-0488).

The rcp protocol allows a server to instruct a client to write to arbitrary files outside of the current directory. This could potentially cause a security issue if a user uses the Kerberos-aware rcp to copy files from a malicious server (CAN-2004-0175).

All users of krb5 should update to these erratum packages which contain backported patches to correct these issues. Red Hat would like to thank the MIT Kerberos Development Team for their responsible disclosure of these issues.

4. Solution:

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

This update is available via Red Hat Network. To use Red Hat Network, launch the Red Hat Update Agent with the following command:

up2date

This will start an interactive process that will result in the appropriate RPMs being upgraded on your system.

5. Bug IDs fixed (http://bugzilla.redhat.com/):

159304 - CAN-2005-0488 telnet Information Disclosure Vulnerability 159753 - CAN-2005-1689 double-free in krb5_recvauth 161471 - krb5 krb5_principal_compare NULL pointer crash 161611 - CAN-2004-0175 malicious rsh server can cause rcp to write to arbitrary files 162255 - CAN-2005-1175 krb5 buffer overflow in KDC