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). It was found that ftpd, a Kerberos-aware FTP server, did not properly drop privileges. On Red Hat Enterprise Linux 5, the ftpd daemon did not check for the potential failure of the effective group ID change system call. If the group ID change failed, a remote FTP user could use this flaw to gain unauthorized read or write access to files that are owned by the root group. Updated packages are available from ftp.redhat.com.
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 ===================================================================== Red Hat Security Advisory Synopsis: Low: krb5 security and bug fix update Advisory ID: RHSA-2012:0306-03 Product: Red Hat Enterprise Linux Advisory URL: https://rhn.redhat.com/errata/RHSA-2012-0306.html Issue date: 2012-02-21 CVE Names: CVE-2011-1526 ===================================================================== 1. Summary: Updated krb5 packages that fix one security issue and various bugs are now available for Red Hat Enterprise Linux 5. The Red Hat Security Response Team has rated this update as having low 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. 2. Relevant releases/architectures: RHEL Desktop Workstation (v. 5 client) - i386, x86_64 Red Hat Enterprise Linux (v. 5 server) - i386, ia64, ppc, s390x, x86_64 Red Hat Enterprise Linux Desktop (v. 5 client) - i386, x86_64 3. 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). It was found that ftpd, a Kerberos-aware FTP server, did not properly drop privileges. On Red Hat Enterprise Linux 5, the ftpd daemon did not check for the potential failure of the effective group ID change system call. If the group ID change failed, a remote FTP user could use this flaw to gain unauthorized read or write access to files that are owned by the root group. (CVE-2011-1526) Red Hat would like to thank the MIT Kerberos project for reporting this issue. Upstream acknowledges Tim Zingelman as the original reporter. This update also fixes the following bugs: * Due to a mistake in the Kerberos libraries, a client could fail to contact a Key Distribution Center (KDC) or terminate unexpectedly if the client had already more than 1024 file descriptors in use. This update backports modifications to the Kerberos libraries and the libraries use the poll() function instead of the select() function, as poll() does not have this limitation. (BZ#701444) * The KDC failed to release memory when processing a TGS (ticket-granting server) request from a client if the client request included an authenticator with a subkey. As a result, the KDC consumed an excessive amount of memory. With this update, the code releasing the memory has been added and the problem no longer occurs. (BZ#708516) * Under certain circumstances, if services requiring Kerberos authentication sent two authentication requests to the authenticating server, the second authentication request was flagged as a replay attack. As a result, the second authentication attempt was denied. This update applies an upstream patch that fixes this bug. (BZ#713500) * Previously, if Kerberos credentials had expired, the klist command could terminate unexpectedly with a segmentation fault when invoked with the -s option. This happened when klist encountered and failed to process an entry with no realm name while scanning the credential cache. With this update, the underlying code has been modified and the command handles such entries correctly. (BZ#729067) * Due to a regression, multi-line FTP macros terminated prematurely with a segmentation fault. This occurred because the previously-added patch failed to properly support multi-line macros. This update restores the support for multi-line macros and the problem no longer occurs. (BZ#735363, BZ#736132) All users of krb5 are advised to upgrade to these updated packages, which resolve 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 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 5. Bugs fixed (http://bugzilla.redhat.com/): 701444 - Fix libkrb5 to work when > 1024 file descriptors are in use 708516 - memory leak during kdc TGS request 711419 - CVE-2011-1526 krb5, krb5-appl: ftpd incorrect group privilege dropping (MITKRB5-SA-2011-005) 729067 - klist -s segfaults with expired credentials 750823 - Newly introduced defect into krb5 6. Package List: Red Hat Enterprise Linux Desktop (v. 5 client): Source: ftp://ftp.redhat.com/pub/redhat/linux/enterprise/5Client/en/os/SRPMS/krb5-1.6.1-70.el5.src.rpm i386: krb5-debuginfo-1.6.1-70.el5.i386.rpm krb5-libs-1.6.1-70.el5.i386.rpm krb5-workstation-1.6.1-70.el5.i386.rpm x86_64: krb5-debuginfo-1.6.1-70.el5.i386.rpm krb5-debuginfo-1.6.1-70.el5.x86_64.rpm krb5-libs-1.6.1-70.el5.i386.rpm krb5-libs-1.6.1-70.el5.x86_64.rpm krb5-workstation-1.6.1-70.el5.x86_64.rpm RHEL Desktop Workstation (v. 5 client): Source: ftp://ftp.redhat.com/pub/redhat/linux/enterprise/5Client/en/os/SRPMS/krb5-1.6.1-70.el5.src.rpm i386: krb5-debuginfo-1.6.1-70.el5.i386.rpm krb5-devel-1.6.1-70.el5.i386.rpm krb5-server-1.6.1-70.el5.i386.rpm krb5-server-ldap-1.6.1-70.el5.i386.rpm x86_64: krb5-debuginfo-1.6.1-70.el5.i386.rpm krb5-debuginfo-1.6.1-70.el5.x86_64.rpm krb5-devel-1.6.1-70.el5.i386.rpm krb5-devel-1.6.1-70.el5.x86_64.rpm krb5-server-1.6.1-70.el5.x86_64.rpm krb5-server-ldap-1.6.1-70.el5.x86_64.rpm Red Hat Enterprise Linux (v. 5 server): Source: ftp://ftp.redhat.com/pub/redhat/linux/enterprise/5Server/en/os/SRPMS/krb5-1.6.1-70.el5.src.rpm i386: krb5-debuginfo-1.6.1-70.el5.i386.rpm krb5-devel-1.6.1-70.el5.i386.rpm krb5-libs-1.6.1-70.el5.i386.rpm krb5-server-1.6.1-70.el5.i386.rpm krb5-server-ldap-1.6.1-70.el5.i386.rpm krb5-workstation-1.6.1-70.el5.i386.rpm ia64: krb5-debuginfo-1.6.1-70.el5.i386.rpm krb5-debuginfo-1.6.1-70.el5.ia64.rpm krb5-devel-1.6.1-70.el5.ia64.rpm krb5-libs-1.6.1-70.el5.i386.rpm krb5-libs-1.6.1-70.el5.ia64.rpm krb5-server-1.6.1-70.el5.ia64.rpm krb5-server-ldap-1.6.1-70.el5.ia64.rpm krb5-workstation-1.6.1-70.el5.ia64.rpm ppc: krb5-debuginfo-1.6.1-70.el5.ppc.rpm krb5-debuginfo-1.6.1-70.el5.ppc64.rpm krb5-devel-1.6.1-70.el5.ppc.rpm krb5-devel-1.6.1-70.el5.ppc64.rpm krb5-libs-1.6.1-70.el5.ppc.rpm krb5-libs-1.6.1-70.el5.ppc64.rpm krb5-server-1.6.1-70.el5.ppc.rpm krb5-server-ldap-1.6.1-70.el5.ppc.rpm krb5-workstation-1.6.1-70.el5.ppc.rpm s390x: krb5-debuginfo-1.6.1-70.el5.s390.rpm krb5-debuginfo-1.6.1-70.el5.s390x.rpm krb5-devel-1.6.1-70.el5.s390.rpm krb5-devel-1.6.1-70.el5.s390x.rpm krb5-libs-1.6.1-70.el5.s390.rpm krb5-libs-1.6.1-70.el5.s390x.rpm krb5-server-1.6.1-70.el5.s390x.rpm krb5-server-ldap-1.6.1-70.el5.s390x.rpm krb5-workstation-1.6.1-70.el5.s390x.rpm x86_64: krb5-debuginfo-1.6.1-70.el5.i386.rpm krb5-debuginfo-1.6.1-70.el5.x86_64.rpm krb5-devel-1.6.1-70.el5.i386.rpm krb5-devel-1.6.1-70.el5.x86_64.rpm krb5-libs-1.6.1-70.el5.i386.rpm krb5-libs-1.6.1-70.el5.x86_64.rpm krb5-server-1.6.1-70.el5.x86_64.rpm krb5-server-ldap-1.6.1-70.el5.x86_64.rpm krb5-workstation-1.6.1-70.el5.x86_64.rpm These packages are GPG signed by Red Hat for security. Our key and details on how to verify the signature are available from https://access.redhat.com/security/team/key/#package 7. References: https://www.redhat.com/security/data/cve/CVE-2011-1526.html https://access.redhat.com/security/updates/classification/#low http://web.mit.edu/kerberos/advisories/MITKRB5-SA-2011-005.txt 8. Contact: The Red Hat security contact is <email@example.com>. More contact details at https://access.redhat.com/security/team/contact/ Copyright 2012 Red Hat, Inc. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.4 (GNU/Linux) iD8DBQFPQyNqXlSAg2UNWIIRAp5dAKDA7lUaUiUGF//stQQ4uVUoI9ovlgCdFfCs odSE4hVfYjWSJazvR3Zb0jc= =s8Va -----END PGP SIGNATURE-----