#VU49149 Use of hard-coded credentials in ZyXEL Communications Corp. products - CVE-2020-29583

Vulnerability identifier: #VU49149

Vulnerability risk: Critical

CVSSv4.0: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:A/U:Red]

CVE-ID: CVE-2020-29583

CWE-ID: CWE-798

Exploitation vector: Network

Exploit availability: Yes

Vulnerable software:
NXC2500
Hardware solutions / Routers & switches, VoIP, GSM, etc
NXC5500
Hardware solutions / Routers & switches, VoIP, GSM, etc
ZyXEL ZLD
Hardware solutions / Firmware

Vendor: ZyXEL Communications Corp.

Description

The vulnerability allows a remote attacker to gain full access to vulnerable system.

The vulnerability exists due to presence of hard-coded account zyfwp with an unchangeable password. A remote unauthenticated attacker can access the affected system via ssh or web interface using the hard-coded credentials and gain administrative privileges.

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

Mitigation
Install updates from vendor's website.

Vulnerable software versions

NXC2500: before 6.10 Patch1

NXC5500: before 6.10 Patch1

ZyXEL ZLD: 4.60

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External links
https://ftp.zyxel.com/USG40/firmware/USG40_4.60(AALA.1)C0_2.pdf
https://businessforum.zyxel.com/discussion/5252/zld-v4-60-revoke-and-wk48-firmware-release
https://businessforum.zyxel.com/discussion/5254/whats-new-for-zld4-60-patch-1-available-on-dec-15
https://www.eyecontrol.nl/blog/undocumented-user-account-in-zyxel-products.html
https://www.zyxel.com/support/CVE-2020-29583.shtml
https://www.zyxel.com/support/security_advisories.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.