Bug 52041 – [CVE-2020-1472] Zerologin impact on Samba in UCS

Bug 52041 - [CVE-2020-1472] Zerologin impact on Samba in UCS


Summary:	[CVE-2020-1472] Zerologin impact on Samba in UCS

Status:	RESOLVED WORKSFORME

Product:	UCS
Classification:	Unclassified
Component:	Samba
Version:	UCS 4.4
Hardware:	Other Linux

Importance:	P5 normal (vote)
Target Milestone:	---
Assigned To:	Erik Damrose
QA Contact:	Arvid Requate

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Reported:	2020-09-16 12:16 CEST by Erik Damrose
Modified:	2020-09-23 18:13 CEST (History)
CC List:	1 user (show)

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What kind of report is it?:	Development Internal
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Description Erik Damrose

2020-09-16 12:16:24 CEST

According to upstream information, Samba is not affected when the server option 'server schannel = yes' is configured - this is the default in Samba and in UCS.

https://bugzilla.samba.org/show_bug.cgi?id=14497

SDB article with more information and links:
https://help.univention.com/t/16107

Comment 1 Erik Damrose

2020-09-16 12:29:51 CEST

Tested with zerologon_tester.py from https://github.com/SecuraBV/CVE-2020-1472

Default samba app installation is unaffected, with multiple runs of the tool (the way the test works has a 0.04% false negative chance).

When configuring "server schannel = no" in smb.conf, the check reliably detects the vulnerability

Comment 2 Erik Damrose

2020-09-16 15:40:04 CEST

Samba mailinglist announcement
https://lists.samba.org/archive/samba-announce/2020/000534.html

Comment 3 Erik Damrose

2020-09-17 17:39:24 CEST

As the default UCS configuration is secure, we can resolve this as worksforme. Further improvements from upstream will be incorporated in future samba versions in UCS.

Comment 4 Erik Damrose

2020-09-23 18:13:56 CEST

A mitigation is available with Samba 4.10.18, see bug 52130