Bug 1309992 (CVE-2015-7560)

Summary:	CVE-2015-7560 samba: Incorrect ACL get/set allowed on symlink path
Product:	[Other] Security Response	Reporter:	Huzaifa S. Sidhpurwala <huzaifas>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	aavati, asn, gdeschner, jarrpa, madam, nlevinki, rfortier, sbose, security-response-team, sgirijan, sisharma, smohan, ssaha, vbellur
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	samba 4.4.0rc4, samba 4.3.6, samba 4.2.9, samba 4.1.23	Doc Type:	Bug Fix
Doc Text:	A flaw was found in the way Samba handled ACLs on symbolic links. An authenticated user could use this flaw to gain access to an arbitrary file or directory by overwriting its ACL.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2016-03-24 02:50:01 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1314667, 1314668, 1314669, 1314670, 1314671, 1314672, 1314673, 1314674, 1315942
Bug Blocks:	1309971

Description Huzaifa S. Sidhpurwala 2016-02-19 07:27:25 UTC

As per upstream security advisory:

All versions of Samba from 3.2.0 to 4.3.3 inclusive are vulnerable to a malicious client overwriting the ownership of ACLs using symlinks.

An authenticated malicious client can use SMB1 UNIX extensions to create a symlink to a file or directory, and then use non-UNIX SMB1 calls to overwrite the contents of the ACL on the file or directory linked to.

Comment 1 Andreas Schneider 2016-02-26 08:39:46 UTC

Workaround
==========

Add the parameter:

unix extensions = no

to the [global] section of your smb.conf and restart smbd.

Alternatively, prohibit the use of SMB1 by setting the parameter:

server min protocol = SMB2

to the [global] section of your smb.conf and restart smbd.

Comment 5 Siddharth Sharma 2016-03-09 04:28:26 UTC

Created samba tracking bugs for this issue:

Affects: fedora-all [bug 1315942]

Comment 6 Huzaifa S. Sidhpurwala 2016-03-09 04:37:04 UTC

External References:

https://www.samba.org/samba/security/CVE-2015-7560.html

Comment 7 Siddharth Sharma 2016-03-09 09:59:30 UTC

Acknowledgment:

Name: the Samba project
Upstream: Jeremy Allison (Google), the Samba team

Comment 9 Siddharth Sharma 2016-03-15 06:14:45 UTC

Upstream Patches:

Samba/master

[Patch: 01/12] https://git.samba.org/?p=samba.git;a=patch;h=841ae4a2e297d9d2211d8fb79c8f180ae295aae9
[Patch: 02/12] https://git.samba.org/?p=samba.git;a=patch;h=19eb1c9311955b769afdc9ff593a21800424cf27
[Patch: 03/12] https://git.samba.org/?p=samba.git;a=patch;h=6b61b5448a96c762ddae36e5055050c5ca869ea2
[Patch: 04/12] https://git.samba.org/?p=samba.git;a=patch;h=e7e23e96478870a3bf37b8b2d984890feabcf808
[Patch: 05/12] https://git.samba.org/?p=samba.git;a=patch;h=77b3d5b2a8848303070ba2e44476534885469a00
[Patch: 06/12] https://git.samba.org/?p=samba.git;a=patch;h=3f491d77567ddc1b51f6c77c94d26b4d4cc2e5d0
[Patch: 07/12] https://git.samba.org/?p=samba.git;a=patch;h=464d044145faa6db166e9bf4c080a3dd15422834
[Patch: 08/12] https://git.samba.org/?p=samba.git;a=patch;h=0be0b755cdd2a74cf364e69c3babeb714244a604
[Patch: 09/12] https://git.samba.org/?p=samba.git;a=patch;h=5941d75fd4380455d6e0552e8f92b5e7c0c356d6
[Patch: 10/12] https://git.samba.org/?p=samba.git;a=patch;h=9ee4ddd36656370e252405fae07ddd7b782f28bd
[Patch: 11/12] https://git.samba.org/?p=samba.git;a=patch;h=306a7f39add1f0b58b2705499405b7d81bf36793
[Patch: 12/12] https://git.samba.org/?p=samba.git;a=patch;h=b551cd83ef74340adaf88629a9ee9fa5c5215ec6

Comment 13 errata-xmlrpc 2016-03-15 12:31:14 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 6

Via RHSA-2016:0449 https://rhn.redhat.com/errata/RHSA-2016-0449.html

Comment 14 errata-xmlrpc 2016-03-15 12:31:29 UTC

This issue has been addressed in the following products:

  Red Hat Gluster Storage 3.1 for RHEL 7
  Red Hat Gluster Storage 3.1 for RHEL 6

Via RHSA-2016:0447 https://rhn.redhat.com/errata/RHSA-2016-0447.html

Comment 15 errata-xmlrpc 2016-03-15 13:19:01 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7
  Red Hat Enterprise Linux 6

Via RHSA-2016:0448 https://rhn.redhat.com/errata/RHSA-2016-0448.html