Bug 1290294 (CVE-2015-8467)

Summary: CVE-2015-8467 samba: Denial of service attack against Windows Active Directory server.
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: aavati, asn, gdeschner, jarrpa, nlevinki, rfortier, sbose, security-response-team, sgirijan, sisharma, smohan, ssaha, vbellur
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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Fixed In Version: Doc Type: Bug Fix
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Last Closed: 2015-12-17 04:12:57 UTC Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On:    
Bug Blocks: 1281327    

Description Huzaifa S. Sidhpurwala 2015-12-10 05:45:29 UTC 
As per samba upstream advisory:

Samba, operating as an AD DC, is sometimes operated in a domain with a mix of Samba and Windows Active Directory Domain Controllers.

All versions of Samba from 4.0.0 to 4.3.2 inclusive, when deployed as an AD DC in the same domain with Windows DCs, could be used to override the protection against the MS15-096 / CVE-2015-2535 security issue in Windows.

Prior to MS16-096 it was possible to bypass the quota of machine accounts a non-administrative user could create.  Pure Samba domains are not impacted, as Samba does not implement the SeMachineAccountPrivilege functionality to allow non-administrator users to create new computer objects.

The following mitigation was suggested by upstream:

Only users with SeMachineAccountPrivilege can exploit this issue in Windows, removing this privilege from "Authenticated Users" can provide a mitigation.
Comment 1 Huzaifa S. Sidhpurwala 2015-12-10 06:36:29 UTC 
Acknowledgements:

Red Hat would like to thank the Samba project for reporting this issue. Upstream  cknowledges Andrew Bartlett of the Samba Team and Catalyst as the original reporters.
Comment 2 Huzaifa S. Sidhpurwala 2015-12-17 04:12:57 UTC 
External References:

https://www.samba.org/samba/security/CVE-2015-8467.html