Man-in-the-Middle attack in samba (Alpine package)

1) Man-in-the-Middle attack

EUVDB-ID: #VU8516

Risk: Low

CVSSv3.1: 5.5 [CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:U/RL:O/RC:C]

CVE-ID: CVE-2017-12150

CWE-ID: CWE-310 - Cryptographic Issues

Exploit availability: No

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.

Mitigation

Install update from vendor's website.

Vulnerable software versions

samba (Alpine package): 3.4.8-r0 - 4.4.14-r1

CPE2.3

• cpe:2.3:o:alpine:samba_alpine_package:4.2.14-r2:*:*:*:*:alpine_linux:*:
• cpe:2.3:o:alpine:samba_alpine_package:4.2.14-r1:*:*:*:*:alpine_linux:*:
• cpe:2.3:o:alpine:samba_alpine_package:4.1.8-r0:*:*:*:*:alpine_linux:*:

External links

http://git.alpinelinux.org/aports/commit/?id=4013d75e416cb0c1c59bbb3f7ac07d1db141473a
http://git.alpinelinux.org/aports/commit/?id=1c38a7f3b9cd01ff44f483b6f375aee36076925c
http://git.alpinelinux.org/aports/commit/?id=d07f3a244e0806b4e3fe99e12c4d9ddc9a07f8b0

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the local network (LAN).

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.