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Critical Vulnerability in Zyxel Firewall and VPN Products Exploited

Critical Vulnerability in Zyxel Firewall and VPN Products Exploited

May 16, 2022

Threat actors exploit the critical vulnerability affecting Zyxel’s firewall and VPN devices. The vulnerability allows attackers to inject arbitrary commands without authentication remotely. Zyxel has recently released patches for it.

The vulnerability, code CVE-2022-30525, is “critical” with a CVSS score of 9.8. It allows threat actors to gain full access to corporate networks and devices. In an article published on Rapid7, researchers also shared a technical analysis of the details of the exploit.

Threat actors are closely watching vulnerability trends and your public-facing services and technologies to find a backdoorUse SOCRadar for vulnerability intelligence and see which vulnerabilities are leveraged by threat actors.

Allows to Create “Reverse Shell”

According to cybersecurity researchers, attackers who exploit the vulnerability can execute commands as “nobody user.” The vulnerability is exploited via the /ztp/cgi-bin/handler URI and by passing commands to os.system in lib_wan_settings.py.

With this method, cyber attackers can create a reverse shell using normal bash GTFOBin.

Which Zyxel Products Does the Vulnerability Affect?

Zyxel shared the affected products and patches with its users in its security advisory:

Affected model

Affected firmware version

Patch

USG FLEX 100(W), 200, 500, 700

ZLD V5.00 through ZLD V5.21 Patch 1

ZLD V5.30

USG FLEX 50(W) / USG20(W)-VPN

ZLD V5.10 through ZLD V5.21 Patch 1

ZLD V5.30

ATP series

ZLD V5.10 through ZLD V5.21 Patch 1

ZLD V5.30

VPN series

ZLD V4.60 through ZLD V5.21 Patch 1

ZLD V5.30

Rapid7 researchers announced that they detected close to 17,000 devices connected to the internet in their scan through Shodan for vulnerable Zyxel products.

Shodan search results for vulnerable Zyxel devices.
Shodan search results for vulnerable Zyxel devices. (Source: Rapid7)

Cybersecurity experts point out the damage that the vulnerability can cause and that it is actively exploited and state that it is of great importance to update software versions.

SonicWall Releases Patches for Vulnerabilities Affecting SSLVPN SMA1000 Devices

SonicWall announced that it had released patches for three vulnerabilities, including the critical “unauthenticated access control bypass” vulnerability. Its security advisory stated that the vulnerabilities affect firmware versions 12.4.0 and 12.4.1 running SMA 6200, 6210, 7200, 7210, and 8000v.

Here is the complete list of vulnerabilities:

  • CVE-2022-22282 (CVSS 8.2): Unauthenticated Access Control Bypass Vulnerability
  • CVE-2022-1702 (CVSS 6.1): Open Redirection Vulnerability
  • CVE-2022-1701 (CVSS 5.7): Use of Hard-coded Cryptographic Key Vulnerability

The vulnerabilities do not affect SMA 1000 series, SMA 100 series, CMS, and remote access users running versions before 12.4.0.

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