Vulnerability identifier: #VU25597

Vulnerability risk: High

CVSSv3.1: 9.4 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C]

CVE-ID: CVE-2020-9054

CWE-ID: CWE-78

Exploitation vector: Network

Exploit availability: Yes

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
NSA210
Hardware solutions / Routers for home users
NSA220
Hardware solutions / Routers for home users
NSA220+
Hardware solutions / Routers for home users
NSA221
Hardware solutions / Routers for home users
NSA310
Hardware solutions / Routers for home users
NSA310S
Hardware solutions / Routers for home users
NSA320
Hardware solutions / Routers for home users
NSA320S
Hardware solutions / Routers for home users
NSA325
Hardware solutions / Routers for home users
NSA325v2
Hardware solutions / Routers for home users

Vendor: ZyXEL Communications Corp.

Description

The vulnerability allows a remote attacker to execute arbitrary shell commands on the target system.

The vulnerability exists due to improper input validation when processing username in the login form. A remote unauthenticated attacker can send a specially crafted HTTP request and execute arbitrary OS commands on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Mitigation

The vendor has released a hotfix for the following models:

• NAS326
• NAS520
• NAS540
• NAS542

Vulnerable software versions

Zyxel NAS 326: 5.21

NAS520: 5.21

NAS540: 5.21

NAS542: 5.21

NSA210: All versions

NSA220: All versions

NSA220+: All versions

NSA221: All versions

NSA310: All versions

NSA310S: All versions

NSA320: All versions

NSA320S: All versions

NSA325: All versions

NSA325v2: All versions

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External links
http://www.zyxel.com/support/remote-code-execution-vulnerability-of-NAS-products.shtml

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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?

Yes. This vulnerability is being exploited in the wild.