Quantum Secular Labs / Blog / Advisories

CVE-2023-28771: Zyxel Multiple Firewalls OS Command Injection Vulnerability

CVE-2023-28771 is rated critical with a CVSS v3.1 base score of 9.8 and affects Zyxel Multiple Firewalls, along with 19 other products in NVD’s configuration data. Per its scoring, it can be exploited over the network, without authentication, without any user interaction. The scored impact on confidentiality, integrity and availability is the highest available. CISA added it to its Known Exploited Vulnerabilities catalog on 2023-05-31, which means exploitation in the wild has been observed.

Vulnerability description

Improper error message handling in Zyxel ZyWALL/USG series firmware versions 4.60 through 4.73, VPN series firmware versions 4.60 through 5.35, USG FLEX series firmware versions 4.60 through 5.35, and ATP series firmware versions 4.60 through 5.35, which could allow an unauthenticated attacker to execute some OS commands remotely by sending crafted packets to an affected device.

Severity breakdown

CVSS v3.1 9.8: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

  • Attack vector: Network. Exploitable remotely over the network, with no need for local or physical access.
  • Attack complexity: Low. No special conditions; the attack can be repeated reliably.
  • Privileges required: None. No account or prior access is needed.
  • User interaction: None. No action from any user is needed.
  • Scope: Unchanged. Impact stays within the vulnerable component.
  • Confidentiality impact: High. Total loss of confidentiality; sensitive data can be fully disclosed.
  • Integrity impact: High. Total loss of integrity; data or system state can be fully modified.
  • Availability impact: High. Total loss of availability; the component can be shut down.

Underlying weakness

CWE-78: Improper Neutralization of Special Elements used in an OS Command

The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command before it is sent to a downstream component.

Affected products

  • Zyxel Atp100 Firmware: from 4.60 before 5.36
  • Zyxel Atp100w Firmware: from 4.60 before 5.35
  • Zyxel Atp200 Firmware: from 4.60 before 5.36
  • Zyxel Atp500 Firmware: from 4.60 before 5.36
  • Zyxel Atp700 Firmware: from 4.60 before 5.36
  • Zyxel Atp800 Firmware: from 4.60 before 5.36
  • Zyxel Usg Flex 100 Firmware: from 4.60 before 5.36
  • Zyxel Usg Flex 100w Firmware: from 4.60 before 5.36
  • Zyxel Usg Flex 200 Firmware: from 4.60 before 5.36
  • Zyxel Usg Flex 50 Firmware: from 4.60 before 5.36
  • Zyxel Usg Flex 500 Firmware: from 4.60 before 5.36
  • Zyxel Usg Flex 50w Firmware: from 4.60 before 5.36
  • Zyxel Usg Flex 700 Firmware: from 4.60 before 5.36
  • Zyxel Vpn100 Firmware: from 4.60 before 5.36
  • Zyxel Vpn1000 Firmware: from 4.60 before 5.36

References