===================================================================== CERT-Renater Note d'Information No. 2004/VULN396 _____________________________________________________________________ DATE : 15/09/2004 HARDWARE PLATFORM(S) : / OPERATING SYSTEM(S) : Solaris 7, 8, 9. ====================================================================== Document ID: 57580 Title: Document ID 57580 Synopsis: Solaris/SEAM Kerberos 5 Vulnerability Due To Buffer Overflows In krb5_aname_to_localname() Update Date: 2004-09-13 _________________________________________________________________ Description [25]Top Sun(sm) Alert Notification * Sun Alert ID: 57580 * Synopsis: Solaris/SEAM Kerberos 5 Vulnerability Due To Buffer Overflows In krb5_aname_to_localname() * Category: Security * Product: Solaris, Solaris Enterprise Authentication Mechanism (SEAM) * BugIDs: 5055875 * Avoidance: Workaround * State: Committed * Date Released: 10-Jun-2004 * Date Closed: * Date Modified: 1. Impact On Kerberos 5 enabled systems using auth_to_local mapping through appropriate entries in the krb5 configuration file krb5.conf(4); an unprivileged local or remote user with kerberos credentials may be able to execute arbitrary code with root privileges due to buffer overflows in krb5_aname_to_localname() function. This issue is described in CERT vulnerability VU#686862 at [26]http://www.kb.cert.org/vuls/id/686862 and MIT krb5 Security Advisory 2004-001 at [27]http://web.mit.edu/kerberos/advisories/MITKRB5-SA-2004-001-an_to_l n.txt. 2. Contributing Factors This issue can occur in the following releases: SPARC Platform * Solaris 8 * Solaris 9 * SEAM 1.0 (for Solaris 7) * SEAM 1.0.1 (for Solaris 8) * SEAM 1.0.2 (for Solaris 9) x86 Platform * Solaris 8 * Solaris 9 * SEAM 1.0 (for Solaris 7) * SEAM 1.0.1 (for Solaris 8) * SEAM 1.0.2 (for Solaris 9) Note: Solaris Enterprise Authentication Mechanism (SEAM) is an unbundled product available for Solaris 7, 8 and 9. For more information on SEAM, please see the SEAM(5) man page. For Solaris without SEAM, this issue may only occur if the system is configured to be a Kerberos client, verified by running the following command: % grep default_realm /etc/krb5/krb5.conf | grep -v __default_realm__ default_realm = EXAMPLE.COM If the command returns no output or the krb5.conf(4) file is not found, then the system is not configured for Kerberos. In addition, systems are only vulnerable to this issue if they have been configured to enable the "explicit" mapping or "rules-based" mapping of the principal mapping functionality. This is not the default configuration. A system which is vulnerable will have one of the following entries in the krb5 configuration file (see krb5.conf(4)): The explicit mapping form is similar to: auth_to_local_names = { aname = lname } The rule-based mapping form is similar to: auth_to_local = RULE:foo 3. Symptoms There are no predictable symptoms that would indicate the described issue has been exploited. Solution Summary [28]Top 4. Relief/Workaround To work around the described issue, disable the "auth_to_local" rules by commenting out the code for "auth_to_local" from the "/etc/krb5/krb5.conf" configuration file. 5. Resolution A final resolution is pending completion. This Sun Alert notification is being provided to you on an "AS IS" basis. This Sun Alert notification may contain information provided by third parties. The issues described in this Sun Alert notification may or may not impact your system(s). Sun makes no representations, warranties, or guarantees as to the information contained herein. ANY AND ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT, ARE HEREBY DISCLAIMED. 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