Man-in-the-Middle attack in Samba - CVE-2017-12150
Published: September 20, 2017
Vulnerability identifier: #VU8516
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2017-12150
CWE-ID: CWE-310
Exploitation vector: Adjecent network
Exploit availability:
No public exploit available
Vendor: Samba
Affected software:
Samba
Samba
Detailed vulnerability description
The vulnerability allows a remote attacker to perform MitM attack.
The vulnerability exists due to several Samba tools do not require signing for SMB connections. The affected tools are:
- 'smb2mount -e', 'smbcacls -e' and 'smbcquotas -e',;
- the python binding exported as 'samba.samba3.libsmb_samba_internal' doesn't make use of the "client signing" smb.conf option;
- libgpo as well as 'net ads gpo' doesn't require SMB signing when fetching group policies
- commandline tools like 'smbclient', 'smbcacls' and 'smbcquotas' allow a fallback to an anonymous connection when using the '--use-ccache' option and this happens even if SMB signing is required.
Successful exploitation of the vulnerability may allow an attacker to perform MitM attack and gain access to potentially sensitive information or elevate privileges on the server.
The vulnerability exists due to several Samba tools do not require signing for SMB connections. The affected tools are:
- 'smb2mount -e', 'smbcacls -e' and 'smbcquotas -e',;
- the python binding exported as 'samba.samba3.libsmb_samba_internal' doesn't make use of the "client signing" smb.conf option;
- libgpo as well as 'net ads gpo' doesn't require SMB signing when fetching group policies
- commandline tools like 'smbclient', 'smbcacls' and 'smbcquotas' allow a fallback to an anonymous connection when using the '--use-ccache' option and this happens even if SMB signing is required.
Successful exploitation of the vulnerability may allow an attacker to perform MitM attack and gain access to potentially sensitive information or elevate privileges on the server.
How to mitigate CVE-2017-12150
Install patch from vendor's website:
https://www.samba.org/samba/ftp/patches/security/samba-4.4.15-security-2017-09-20.patch
https://www.samba.org/samba/ftp/patches/security/samba-4.5.13-security-2017-09-20.patch
https://www.samba.org/samba/ftp/patches/security/samba-4.6.7-security-2017-09-20.patch
Additionally 4.6.8, 4.5.14 and 4.4.16 have been issued as security releases to correct the defect.
https://www.samba.org/samba/ftp/patches/security/samba-4.4.15-security-2017-09-20.patch
https://www.samba.org/samba/ftp/patches/security/samba-4.5.13-security-2017-09-20.patch
https://www.samba.org/samba/ftp/patches/security/samba-4.6.7-security-2017-09-20.patch
Additionally 4.6.8, 4.5.14 and 4.4.16 have been issued as security releases to correct the defect.