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Bug 2019726 (CVE-2020-25718)

Summary: CVE-2020-25718 samba: Samba AD DC did not correctly sandbox Kerberos tickets issues by an RODC
Product: [Other] Security Response Reporter: Huzaifa S. Sidhpurwala <huzaifas>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED NOTABUG QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: abokovoy, anoopcs, asn, dkarpele, gdeschner, hvyas, iboukris, jarrpa, jstephen, lmohanty, madam, pfilipen, puebele, rhs-smb, sbose, security-response-team, ssorce
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Fixed In Version: samba 4.15.2, samba 4.14.10, samba 4.13.14 Doc Type: If docs needed, set a value
Doc Text:
A flaw was found in the way samba, as an Active Directory Domain Controller, is able to support an RODC (read-only domain controller). This would allow an RODC to print administrator tickets.
Story Points: ---
Clone Of: Environment:
Last Closed: 2021-11-10 03:21:14 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On: 2021718    
Bug Blocks: 2022412    

Description Huzaifa S. Sidhpurwala 2021-11-03 09:00:10 UTC
As per upstream advisory:

Samba as an Active Directory Domain Controller is able to support an RODC, which is meant to have minimal privileges in a domain.

However, in accepting a ticket from a Samba or Windows RODC, Samba was not confirming that the RODC is authorized to print such a ticket, via the msDS-NeverRevealGroup and msDS-RevealOnDemandGroup (typically "Allowed RODC Replication Group" and "Denied RODC Replciation Group").

This would allow an RODC to print administrator tickets.

Comment 1 Huzaifa S. Sidhpurwala 2021-11-10 02:54:09 UTC
Created samba tracking bugs for this issue:

Affects: fedora-all [bug 2021718]

Comment 2 Product Security DevOps Team 2021-11-10 03:21:12 UTC
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):