Attachment 16918 Details for Bug 14561 – initial advisory (v01)

initial advisory (v01)

CVE-2020-25718-advisory-v1.txt (text/plain), 2.34 KB, created by Andrew Bartlett on 2021-11-02 10:25:16 UTC

(hide)

Description:

Filename:

MIME Type:

Creator: Andrew Bartlett

Created: 2021-11-02 10:25:16 UTC

Size: 2.34 KB

patch

obsolete

>===========================================================
>== Subject:     Samba AD DC did not always rely on the SID
>==              and PAC in Kerberos tickets.
>==
>== CVE ID#:     CVE-2020-25719
>==
>== Versions:    Samba 4.0.0 and later
>==
>== Summary:     The Samba AD DC, could become confused about
>==              the user a ticket represents if it did not
>==              strictly require a Kerberos PAC and always use
>==              the SIDs found within.
>===========================================================
>
>===========
>Description
>===========
>
>Samba as an Active Directory Domain Controller is based on Kerberos,
>which is a name-based authorization protocol.
>
>However Microsoft Windows and Active Direcory is SID-based, and at the
>meeting of these two points it is possible to confuse a server into
>acting as one user when holding a ticket for another.
>
>A simple example is on Samba's LDAP server, which would, unless
>"gensec:require_pac = true" was set, permit a fall back to using the
>name in the ticket alone.  
>
>Users (delegated administrators) with the right to create other users
>or computers can then abuse the race (between time of ticket issue and
>time of presentation), to become a different user, if they name the
>accounts carefully.
>
>==================
>Patch Availability
>==================
>
>Patches addressing both these issues have been posted to:
>
>    https://www.samba.org/samba/security/
>
>Additionally, Samba  4.15.2, 4.14.10 and 4.13.14 have been issued
>as security releases to correct the defect.  Samba administrators are
>advised to upgrade to these releases or apply the patch as soon
>as possible.
>
>==================
>CVSSv3 calculation
>==================
>
>This CVSSv3 calculation is assuming the other Samba issues are
>addressed, and user/computer creation is an at least partially
>privileged action.
>
>CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H (7.8)
>
>==========
>Workaround
>==========
>
>
>=======
>Credits
>=======
>
>Originally reported by Andrew Bartlett.
>
>Patches provided by:
> - Andrew Bartlett of Catalyst and the Samba Team.
> - Joseph Sutton of Catalyst and the Samba Team
> - Stefan Metzmacher of SerNet and the Samba Team
>
>Advisory written by Andrew Bartlett of Catalyst
>
>==========================================================
>== Our Code, Our Bugs, Our Responsibility.
>== The Samba Team
>==========================================================
>

Actions: View

Attachments on bug 14561: 16918 | 16922 | 16979 | 16980