#VU20809 Permissions, Privileges, and Access Controls in Samba - CVE-2019-10197

Vulnerability identifier: #VU20809

Vulnerability risk: Medium

CVSSv4.0: 1.3 [CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2019-10197

CWE-ID: CWE-264

Exploitation vector: Local network

Exploit availability: No

Vulnerable software:
Samba
Server applications / Directory software, identity management

Vendor: Samba

Description

The vulnerability allows a remote attacker to escalate privileges on the system.

The vulnerability exists due to an error related to caching of responses when the 'wide links' option is explicitly set to 'yes' and either 'unix extensions = no' or 'allow insecure wide links = yes' is set in addition. A remote attacker can that does not have access to a share can send a series of request to an SMB share and gain access to the global root directory on the system.

Successful exploitation of the vulnerability may allow an attacker to read or modify arbitrary files on the system. Note, that unix permissions enforced by kernel will still apply.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Samba: 4.9.0 - 4.9.12, 4.10.0 - 4.10.7

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External links
https://www.samba.org/samba/security/CVE-2019-10197.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 local network (LAN).

Is there known malware, which exploits this vulnerability?

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