Multiple vulnerabilities in Samba

Published: 2019-04-08

Risk	Low
Patch available	YES
Number of vulnerabilities	2
CVE-ID	CVE-2019-3880 CVE-2019-3870
CWE-ID	CWE-61 CWE-276
Exploitation vector	Local network
Public exploit	N/A
Vulnerable software Subscribe	Samba Server applications / Directory software, identity management
Vendor	Samba

Security Bulletin

This security bulletin contains information about 2 vulnerabilities.

1) Symlink attack

EUVDB-ID: #VU18149

Risk: Low

CVSSv3.1: 4 [CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2019-3880

CWE-ID: CWE-61 - UNIX Symbolic Link (Symlink) Following

Exploit availability: No

Description

The vulnerability allows a remote attacker to bypass certain security restrictions.

The vulnerability exists due to a symlink following issue within the RPC endpoint emulating the Windows registry service API. A remote unprivileged attacker with ability to create a symlink can create a new registry hive file anywhere they have unix permissions to create a new file within a Samba share.

Successful exploitation of this vulnerability may allow an attacker to detect presence of exiting files on the system or perform phishing attacks and trick other users to upload files into insecure locations.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Samba: 4.8.0 - 4.10.1

External links

http://www.samba.org/samba/security/CVE-2019-3880.html

Q & A

Can this vulnerability be exploited remotely?

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

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

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

2) Incorrect default permissions

EUVDB-ID: #VU18148

Risk: Low

CVSSv3.1: 3.9 [CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2019-3870

CWE-ID: CWE-276 - Incorrect Default Permissions

Exploit availability: No

Description

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to incorrect default permissions for files and folders (e.g. 0666) within installation location that are set by the application during the creation of a new Samba AD DC. A local user with access to the system can view contents of files and directories or modify them.

Note, such application behavior can occur on some upgraded Samba versions.