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6 <title>Samba - Security Announcement Archive</title>
11 <H2>CVE-2017-12150.html:</H2>
15 ===============================================================================
16 == Subject: SMB1/2/3 connections may not require signing where they should
18 == CVE ID#: CVE-2017-12150
20 == Versions: Samba 3.0.25 to 4.6.7
22 == Summary: A man in the middle attack may hijack client connections.
24 ===============================================================================
30 There are several code paths where the code doesn't enforce SMB signing:
32 * The fixes for CVE-2015-5296 didn't apply the implied signing protection
33 when enforcing encryption for commands like 'smb2mount -e', 'smbcacls -e' and
36 * The python binding exported as 'samba.samba3.libsmb_samba_internal'
37 doesn't make use of the "client signing" smb.conf option.
39 * libgpo as well as 'net ads gpo' doesn't require SMB signing when fetching
42 * Commandline tools like 'smbclient', 'smbcacls' and 'smbcquotas' allow
43 a fallback to an anonymous connection when using the '--use-ccache'
44 option and this happens even if SMB signing is required.
50 A patch addressing this defect has been posted to
52 https://www.samba.org/samba/security/
54 Additionally 4.6.8, 4.5.14 and 4.4.16 have been issued as
55 security releases to correct the defect. Samba vendors and administrators
56 running affected versions are advised to upgrade or apply the patch as
63 The missing implied signing for 'smb2mount -e', 'smbcacls -e' and
64 'smbcquotas -e' can be enforced by explicitly using '--signing=required'
65 on the commandline or "client signing = required" in smb.conf.
71 This vulnerability was discovered and researched by Stefan Metzmacher of
72 SerNet (https://samba.plus) and the Samba Team (https://www.samba.org),
73 who also provides the fixes.