|Bugzilla:||770325: CVE-2011-4862 krb5: telnet client and server encrypt_keyid heap-based buffer overflow|
The MITRE CVE dictionary describes this issue as:
Buffer overflow in libtelnet/encrypt.c in telnetd in FreeBSD 7.3 through 9.0, MIT Kerberos Version 5 Applications (aka krb5-appl) 1.0.2 and earlier, Heimdal 1.5.1 and earlier, GNU inetutils, and possibly other products allows remote attackers to execute arbitrary code via a long encryption key, as exploited in the wild in December 2011.
A buffer overflow flaw was found in the MIT krb5 telnet daemon (telnetd) as shipped with all supported versions of Red Hat Enterprise Linux. A remote attacker who can access the telnet port of a target machine could use this flaw to execute arbitrary code as root.
While we are aware of public exploits for this issue that include targets for Red Hat Enterprise Linux 3, we are not aware of any yet which would be successful in gaining arbitrary root code execution in Red Hat Enterprise Linux 4, 5, or 6. However it is plausible that one could be created to do so.
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 enabled the krb5 telnet daemon and have it accessible remotely, they should disable it or apply the updates we have released.
Since same encryption code is shared between the MIT krb5 telnet daemon and the telnet client, this issue affects the telnet client as well. The updates we have released fixes the issue for both, the telnet daemon and the telnet client.
CVSS v2 metrics
|Access Vector:||Adjacent Network|
Find out more about Red Hat support for the Common Vulnerability Scoring System (CVSS).
Red Hat security errata
|Red Hat Enterprise Linux ES (v. 3 ELS) (krb5)||RHSA-2011:1853||December 28, 2011|
|Red Hat Enterprise Linux EUS (v. 5.6 server) (krb5)||RHSA-2011:1853||December 28, 2011|
|Red Hat Enterprise Linux Long Life (v. 5.3 server) (krb5)||RHSA-2011:1853||December 28, 2011|
|Red Hat Enterprise Linux Server EUS (v. 6.0) (krb5-appl)||RHSA-2011:1854||December 28, 2011|
|Red Hat Enterprise Linux Server EUS (v. 6.1) (krb5-appl)||RHSA-2011:1854||December 28, 2011|
|Red Hat Enterprise Linux version 4 (krb5)||RHSA-2011:1851||December 27, 2011|
|Red Hat Enterprise Linux version 5 (krb5)||RHSA-2011:1851||December 27, 2011|
|Red Hat Enterprise Linux version 6 (krb5-appl)||RHSA-2011:1852||December 27, 2011|
This page is generated automatically and has not been checked for errors or omissions.
For clarification or corrections please contact the Red Hat Security Response Team.