CVE-2020-25717: Input Validation
First published: Wed Nov 03 2021(Updated: )
A flaw was found in the way Samba maps domain users to local users. An authenticated attacker could use this flaw to cause possible privilege escalation.
Credit: secalert@redhat.com secalert@redhat.com secalert@redhat.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Samba Samba | >=3.0.0<4.13.14 | |
| Samba Samba | >=4.14.0<4.14.10 | |
| Samba Samba | >=4.15.0<4.15.2 | |
| Debian Debian Linux | =9.0 | |
| Debian Debian Linux | =10.0 | |
| Fedoraproject Fedora | =33 | |
| Fedoraproject Fedora | =34 | |
| Fedoraproject Fedora | =35 | |
| Redhat Codeready Linux Builder | ||
| Redhat Gluster Storage | =3.0 | |
| Redhat Gluster Storage | =3.5 | |
| Redhat Openstack | =13 | |
| Redhat Openstack | =16.1 | |
| Redhat Openstack | =16.2 | |
| Redhat Virtualization | =4.0 | |
| Redhat Virtualization Host | =4.0 | |
| Redhat Enterprise Linux | =7.0 | |
| Redhat Enterprise Linux | =8.0 | |
| Redhat Enterprise Linux Desktop | =7.0 | |
| Redhat Enterprise Linux Eus | =8.2 | |
| Redhat Enterprise Linux Eus | =8.4 | |
| Redhat Enterprise Linux For Ibm Z Systems | =7.0 | |
| Redhat Enterprise Linux For Ibm Z Systems | =8.0 | |
| Redhat Enterprise Linux For Ibm Z Systems Eus | =8.2 | |
| Redhat Enterprise Linux For Ibm Z Systems Eus | =8.4 | |
| Redhat Enterprise Linux For Power Big Endian | =7.0 | |
| Redhat Enterprise Linux For Power Little Endian | =7.0 | |
| Redhat Enterprise Linux For Power Little Endian | =8.0 | |
| Redhat Enterprise Linux For Power Little Endian Eus | =8.2 | |
| Redhat Enterprise Linux For Power Little Endian Eus | =8.4 | |
| Redhat Enterprise Linux For Scientific Computing | =7.0 | |
| Redhat Enterprise Linux Resilient Storage | =7.0 | |
| Redhat Enterprise Linux Server | =7.0 | |
| Redhat Enterprise Linux Server Aus | =8.2 | |
| Redhat Enterprise Linux Server Aus | =8.4 | |
| Redhat Enterprise Linux Server Tus | =8.4 | |
| Redhat Enterprise Linux Server Update Services For Sap Solutions | =8.2 | |
| Redhat Enterprise Linux Server Update Services For Sap Solutions | =8.4 | |
| Redhat Enterprise Linux Tus | =8.2 | |
| Redhat Enterprise Linux Workstation | =7.0 | |
| Canonical Ubuntu Linux | =18.04 | |
| Canonical Ubuntu Linux | =20.04 | |
| Canonical Ubuntu Linux | =21.04 | |
| Canonical Ubuntu Linux | =21.10 | |
| redhat/samba | <0:4.10.16-17.el7_9 | 0:4.10.16-17.el7_9 |
| redhat/samba | <0:4.14.5-7.el8_5 | 0:4.14.5-7.el8_5 |
| redhat/samba | <0:4.11.2-18.el8_2 | 0:4.11.2-18.el8_2 |
| redhat/samba | <0:4.13.3-8.el8_4 | 0:4.13.3-8.el8_4 |
| redhat/samba | <0:4.11.6-114.el7 | 0:4.11.6-114.el7 |
| redhat/samba | <0:4.14.5-204.el8 | 0:4.14.5-204.el8 |
| redhat/redhat-virtualization-host | <0:4.3.21-20220126.0.el7_9 | 0:4.3.21-20220126.0.el7_9 |
| redhat/samba | <4.15.2 | 4.15.2 |
| redhat/samba | <4.14.10 | 4.14.10 |
| redhat/samba | <4.13.14 | 4.13.14 |
| ubuntu/samba | <2:4.7.6+dfsg~ubuntu-0ubuntu2.26 | 2:4.7.6+dfsg~ubuntu-0ubuntu2.26 |
| ubuntu/samba | <2:4.13.14+dfsg-0ubuntu0.20.04.1 | 2:4.13.14+dfsg-0ubuntu0.20.04.1 |
| ubuntu/samba | <2:4.13.14+dfsg-0ubuntu0.21.04.1 | 2:4.13.14+dfsg-0ubuntu0.21.04.1 |
| ubuntu/samba | <2:4.13.14+dfsg-0ubuntu0.21.10.1 | 2:4.13.14+dfsg-0ubuntu0.21.10.1 |
| ubuntu/samba | <2:4.13.14+dfsg-0ubuntu1 | 2:4.13.14+dfsg-0ubuntu1 |
| ubuntu/samba | <2:4.13.14+dfsg-0ubuntu1 | 2:4.13.14+dfsg-0ubuntu1 |
| ubuntu/samba | <2:4.13.14+dfsg-0ubuntu1 | 2:4.13.14+dfsg-0ubuntu1 |
| ubuntu/samba | <2:4.13.14+dfsg-0ubuntu1 | 2:4.13.14+dfsg-0ubuntu1 |
| ubuntu/samba | <4.13.14 | 4.13.14 |
| debian/samba | 2:4.9.5+dfsg-5+deb10u3 2:4.9.5+dfsg-5+deb10u5 2:4.13.13+dfsg-1~deb11u5 2:4.13.13+dfsg-1~deb11u6 2:4.17.12+dfsg-0+deb12u1 2:4.19.5+dfsg-1 2:4.19.6+dfsg-1 |
Remedy
Setting "gensec:require_pac=true" in the smb.conf makes, due to a cache prime in winbind, the DOMAIN\user lookup succeed, provided nss_winbind is in use, 'winbind use default domain = no' (the default) and no error paths are hit. It would be prudent to pre-create disabled users in Active Directory matching on all privileged names not held in Active Directory, eg ~~~ samba-tool user add root -H ldap://$SERVER -U$USERNAME%$PASSWORD --random-password samba-tool user add ubuntu -H ldap://$SERVER -U$USERNAME%$PASSWORD --random-password ~~~ (repeat for eg all system users under 1000 in /etc/passwd or special to any other AD-connected services, eg perhaps "admin" for a web-app)
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Reference Links
- https://bugzilla.redhat.com/show_bug.cgi?id=2019672
- https://security.gentoo.org/glsa/202309-06
- https://www.samba.org/samba/security/CVE-2020-25717.html
- https://www.cve.org/CVERecord?id=CVE-2020-25717 https://nvd.nist.gov/vuln/detail/CVE-2020-25717 https://www.samba.org/samba/security/CVE-2020-25717.html
- https://access.redhat.com/errata/RHSA-2021:5192
- https://access.redhat.com/errata/RHSA-2021:5082
- https://access.redhat.com/errata/RHSA-2022:0074
- https://access.redhat.com/errata/RHSA-2022:0008
- https://access.redhat.com/errata/RHSA-2021:4844
- https://access.redhat.com/errata/RHSA-2021:4843
- https://access.redhat.com/errata/RHSA-2022:0443
- https://access.redhat.com/errata/RHSA-2022:0133
- https://access.redhat.com/security/cve/CVE-2020-25717
- https://launchpad.net/bugs/cve/CVE-2020-25717
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=2021716
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=2027186
- https://access.redhat.com/security/cve/cve-2020-25717
- https://bugzilla.samba.org/show_bug.cgi?id=14556
- https://bugzilla.samba.org/show_bug.cgi?id=14725
- https://security-tracker.debian.org/tracker/CVE-2020-25717
- https://www.samba.org/samba/history/samba-4.13.14.html
- https://ubuntu.com/security/notices/USN-5142-1
- https://ubuntu.com/security/notices/USN-5174-1
- https://www.cve.org/CVERecord?id=CVE-2020-25717
- https://nvd.nist.gov/vuln/detail/CVE-2020-25717
- https://ubuntu.com/security/CVE-2020-25717
Parent vulnerabilities
(Appears in the following advisories)
- collector/nvd-api
- collector/redhat-cve
- collector/nvd-index
- agent/type
- agent/last-modified-date
- collector/launchpad-cve
- source/Launchpad
- agent/first-publish-date
- collector/nvd-cve
- source/NVD
- agent/software-canonical-lookup
- collector/redhat-bugzilla
- source/Red Hat
- alias/CVE-2020-25717
- agent/remedy
- agent/weakness
- agent/severity
- agent/references
- agent/author
- agent/tags
- agent/description
- agent/event
- collector/security-tracker-debian
- source/Debian
- agent/softwarecombine
- collector/usn-cve
- source/Ubuntu
- vendor/samba
- canonical/samba samba
- version/samba samba/3.0.0
- version/samba samba/4.14.0
- version/samba samba/4.15.0
- vendor/debian
- canonical/debian debian linux
- version/debian debian linux/9.0
- version/debian debian linux/10.0
- vendor/fedoraproject
- canonical/fedoraproject fedora
- version/fedoraproject fedora/33
- version/fedoraproject fedora/34
- version/fedoraproject fedora/35
- vendor/redhat
- canonical/redhat codeready linux builder
- canonical/redhat gluster storage
- version/redhat gluster storage/3.0
- version/redhat gluster storage/3.5
- canonical/redhat openstack
- version/redhat openstack/13
- version/redhat openstack/16.1
- version/redhat openstack/16.2
- canonical/redhat virtualization
- version/redhat virtualization/4.0
- canonical/redhat virtualization host
- version/redhat virtualization host/4.0
- canonical/redhat enterprise linux
- version/redhat enterprise linux/7.0
- version/redhat enterprise linux/8.0
- canonical/redhat enterprise linux desktop
- version/redhat enterprise linux desktop/7.0
- canonical/redhat enterprise linux eus
- version/redhat enterprise linux eus/8.2
- version/redhat enterprise linux eus/8.4
- canonical/redhat enterprise linux for ibm z systems
- version/redhat enterprise linux for ibm z systems/7.0
- version/redhat enterprise linux for ibm z systems/8.0
- canonical/redhat enterprise linux for ibm z systems eus
- version/redhat enterprise linux for ibm z systems eus/8.2
- version/redhat enterprise linux for ibm z systems eus/8.4
- canonical/redhat enterprise linux for power big endian
- version/redhat enterprise linux for power big endian/7.0
- canonical/redhat enterprise linux for power little endian
- version/redhat enterprise linux for power little endian/7.0
- version/redhat enterprise linux for power little endian/8.0
- canonical/redhat enterprise linux for power little endian eus
- version/redhat enterprise linux for power little endian eus/8.2
- version/redhat enterprise linux for power little endian eus/8.4
- canonical/redhat enterprise linux for scientific computing
- version/redhat enterprise linux for scientific computing/7.0
- canonical/redhat enterprise linux resilient storage
- version/redhat enterprise linux resilient storage/7.0
- canonical/redhat enterprise linux server
- version/redhat enterprise linux server/7.0
- canonical/redhat enterprise linux server aus
- version/redhat enterprise linux server aus/8.2
- version/redhat enterprise linux server aus/8.4
- canonical/redhat enterprise linux server tus
- version/redhat enterprise linux server tus/8.4
- canonical/redhat enterprise linux server update services for sap solutions
- version/redhat enterprise linux server update services for sap solutions/8.2
- version/redhat enterprise linux server update services for sap solutions/8.4
- canonical/redhat enterprise linux tus
- version/redhat enterprise linux tus/8.2
- canonical/redhat enterprise linux workstation
- version/redhat enterprise linux workstation/7.0
- vendor/canonical
- canonical/canonical ubuntu linux
- version/canonical ubuntu linux/18.04
- version/canonical ubuntu linux/20.04
- version/canonical ubuntu linux/21.04
- version/canonical ubuntu linux/21.10
- package-manager/redhat
- package-manager/debian
- package-manager/ubuntu