Vulnerability identifier: #VU101

Vulnerability risk: High

CVSSv3.1: 8.6 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:L/E:U/RL:O/RC:C]

CVE-ID: CVE-2016-2119

CWE-ID: CWE-264

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Samba
Server applications / Directory software, identity management
Oracle Solaris
Operating systems & Components / Operating system
Oracle Linux
Operating systems & Components / Operating system

Vendor: Samba
Oracle

Description
The vulnerability allows a remote attacker to downgrade client signing security controls on the target system.

The vulnerability exists due to state error in Samba. A remote unauthenticated attacker can downgrade the required signing for an SMB2/3 client connection by injecting the SMB2_SESSION_FLAG_IS_GUEST or SMB2_SESSION_FLAG_IS_NULL flags.

Successful exploitation of this vulnerability may result in disclosure of system information.

Mitigation
The vendor has issued a fix (4.2.14, 4.3.11, 4.4.5).

Vulnerable software versions

Samba: 4.0.0, 4.4.4

Oracle Solaris: 11.3

Oracle Linux: 6 - 7

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External links
http://www.samba.org/samba/security/CVE-2016-2119.html
http://www.oracle.com/technetwork/topics/security/bulletinoct2016-3090566.html
http://www.oracle.com/technetwork/topics/security/linuxbulletinjul2016-3090544.html

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

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