#VU34062 Improper access control in ZyXEL Communications Corp. products - CVE-2020-13365

Vulnerability identifier: #VU34062

Vulnerability risk: Medium

CVSSv4.0: 6.2 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2020-13365

CWE-ID: CWE-284

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Zyxel NAS 326
Hardware solutions / Firmware
NAS520
Hardware solutions / Routers for home users
NAS540
Hardware solutions / Routers for home users
NAS542
Hardware solutions / Routers for home users

Vendor: ZyXEL Communications Corp.

Description

The vulnerability allows a remote user to gain unauthorized access to otherwise restricted functionality.

The vulnerability exists due to improper access restrictions in a CGI script for the web application. A remote authenticated attacker can start a Telnet or SSH service and generate a password for the "NsaRescueAngel" user account with root privileges.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Zyxel NAS 326: before V5.21(AAZF.9)C0

NAS520: before V5.21(AASZ.5)C0

NAS540: before V5.21(AATB.6)C0

NAS542: before V5.21(ABAG.6)C0

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External links
https://www.zyxel.com/support/Zyxel-security-advisory-for-NAS-remote-access-vulnerability.shtml

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

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