CVE-2020-9054
Zyxel Multiple NAS Devices OS Command Injection Vulnerability
Does this matter?
Known to be exploited in the wild (CISA KEV, CISA remediation deadline 15 April 2022). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.
Description
Multiple ZyXEL network-attached storage (NAS) devices running firmware version 5.21 contain a pre-authentication command injection vulnerability, which may allow a remote, unauthenticated attacker to execute arbitrary code on a vulnerable device. ZyXEL NAS devices achieve authentication by using the weblogin.cgi CGI executable. This program fails to properly sanitize the username parameter that is passed to it. If the username parameter contains certain characters, it can allow command injection with the privileges of the web server that runs on the ZyXEL device. Although the web server does not run as the root user, ZyXEL devices include a setuid utility that can be leveraged to run any command with root privileges. As such, it should be assumed that exploitation of this vulnerability can lead to remote code execution with root privileges. By sending a specially-crafted HTTP POST or GET request to a vulnerable ZyXEL device, a remote, unauthenticated attacker may be able to execute arbitrary code on the device. This may happen by directly connecting to a device if it is directly exposed to an attacker. However, there are ways to trigger such crafted requests even if an attacker does not have direct connectivity to a vulnerable devices. For example, simply visiting a website can result in the compromise of any ZyXEL device that is reachable from the client system. Affected products include: NAS326 before firmware V5.21(AAZF.7)C0 NAS520 before firmware V5.21(AASZ.3)C0 NAS540 before firmware V5.21(AATB.4)C0 NAS542 before firmware V5.21(ABAG.4)C0 ZyXEL has made firmware updates available for NAS326, NAS520, NAS540, and NAS542 devices. Affected models that are end-of-support: NSA210, NSA220, NSA220+, NSA221, NSA310, NSA310S, NSA320, NSA320S, NSA325 and NSA325v2
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 99.99% probability · 100th percentile
- CISA KEV
- Listed 25 March 2022 · due 15 April 2022
- Weakness
- CWE-78
- Affected
- zyxel/nas326 firmware · zyxel/nas520 firmware · zyxel/nas540 firmware · zyxel/nas542 firmware · zyxel/atp100 firmware · zyxel/atp200 firmware · zyxel/atp500 firmware · zyxel/atp800 firmware · zyxel/usg20-vpn firmware · zyxel/usg20w-vpn firmware · zyxel/usg40 firmware · zyxel/usg40w firmware · zyxel/usg60 firmware · zyxel/usg60w firmware · zyxel/usg110 firmware · zyxel/usg210 firmware · zyxel/usg310 firmware · zyxel/usg1100 firmware · zyxel/usg1900 firmware · zyxel/usg2200 firmware · +7 more
- Source
- cret@cert.org
CISA notes
Apply updates per vendor instructions. https://nvd.nist.gov/vuln/detail/CVE-2020-9054
References
- https://cwe.mitre.org/data/definitions/78.htmlThird Party Advisory
- https://kb.cert.org/artifacts/cve-2020-9054.htmlThird Party Advisory, US Government Resource
- https://kb.cert.org/vuls/id/498544/Third Party Advisory, US Government Resource
- https://krebsonsecurity.com/2020/02/zyxel-fixes-0day-in-network-storage-devices/Exploit, Third Party Advisory
- https://www.zyxel.com/support/remote-code-execution-vulnerability-of-NAS-products.shtmlVendor Advisory
- https://cwe.mitre.org/data/definitions/78.htmlThird Party Advisory
- https://kb.cert.org/artifacts/cve-2020-9054.htmlThird Party Advisory, US Government Resource
- https://kb.cert.org/vuls/id/498544/Third Party Advisory, US Government Resource
- https://krebsonsecurity.com/2020/02/zyxel-fixes-0day-in-network-storage-devices/Exploit, Third Party Advisory
- https://www.zyxel.com/support/remote-code-execution-vulnerability-of-NAS-products.shtmlVendor Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-9054US Government Resource
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.