The validate_as_request function in kdc_util.c in the Key Distribution Center (KDC) in MIT Kerberos 5 (aka krb5) before 1.13.6 and 1.4.x before 1.14.3, when restrict_anonymous_to_tgt is enabled, uses an incorrect client data structure, which allows remote authenticated users to cause a denial of service (NULL pointer dereference and daemon crash) via an S4U2Self request.
Weakness
The product dereferences a pointer that it expects to be valid but is NULL.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Kerberos_5 | Mit | 1.13 (including) | 1.13 (including) |
| Kerberos_5 | Mit | 1.13.1 (including) | 1.13.1 (including) |
| Kerberos_5 | Mit | 1.13.2 (including) | 1.13.2 (including) |
| Kerberos_5 | Mit | 1.13.3 (including) | 1.13.3 (including) |
| Kerberos_5 | Mit | 1.13.4 (including) | 1.13.4 (including) |
| Kerberos_5 | Mit | 1.13.5 (including) | 1.13.5 (including) |
| Kerberos_5 | Mit | 1.13.6 (including) | 1.13.6 (including) |
| Kerberos_5 | Mit | 1.14 (including) | 1.14 (including) |
| Kerberos_5 | Mit | 1.14.1 (including) | 1.14.1 (including) |
| Kerberos_5 | Mit | 1.14.2 (including) | 1.14.2 (including) |
| Red Hat Enterprise Linux 7 | RedHat | krb5-0:1.14.1-26.el7 | * |
| Krb5 | Ubuntu | esm-infra-legacy/trusty | * |
| Krb5 | Ubuntu | esm-infra/xenial | * |
| Krb5 | Ubuntu | precise | * |
| Krb5 | Ubuntu | precise/esm | * |
| Krb5 | Ubuntu | trusty | * |
| Krb5 | Ubuntu | trusty/esm | * |
| Krb5 | Ubuntu | upstream | * |
| Krb5 | Ubuntu | vivid/stable-phone-overlay | * |
| Krb5 | Ubuntu | vivid/ubuntu-core | * |
| Krb5 | Ubuntu | wily | * |
| Krb5 | Ubuntu | xenial | * |
Potential Mitigations
References
- http://krbdev.mit.edu/rt/Ticket/Display.html?id=8458
- http://lists.opensuse.org/opensuse-updates/2016-09/msg00035.html
- http://rhn.redhat.com/errata/RHSA-2016-2591.html
- http://web.mit.edu/kerberos/krb5-1.13/
- http://web.mit.edu/kerberos/krb5-1.14/
- http://www.securityfocus.com/bid/92132
- http://www.securitytracker.com/id/1036442
- https://github.com/krb5/krb5/commit/93b4a6306a0026cf1cc31ac4bd8a49ba5d034ba7
- https://lists.debian.org/debian-lts-announce/2018/01/msg00040.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/AWL3KYFRJIX37EAM4DKCQQIQP2WBKL35/
- http://krbdev.mit.edu/rt/Ticket/Display.html?id=8458
- http://lists.opensuse.org/opensuse-updates/2016-09/msg00035.html
- http://rhn.redhat.com/errata/RHSA-2016-2591.html
- http://web.mit.edu/kerberos/krb5-1.13/
- http://web.mit.edu/kerberos/krb5-1.14/
- http://www.securityfocus.com/bid/92132
- http://www.securitytracker.com/id/1036442
- https://github.com/krb5/krb5/commit/93b4a6306a0026cf1cc31ac4bd8a49ba5d034ba7
- https://lists.debian.org/debian-lts-announce/2018/01/msg00040.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/AWL3KYFRJIX37EAM4DKCQQIQP2WBKL35/