Zyxel ZyWALL/USG 4.605.35 Error Msg Disclosure Enables Remote OS Cmd
CVE-2023-28771 Published on April 25, 2023
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.
Known Exploited Vulnerability
This Zyxel Multiple Firewalls OS Command Injection Vulnerability is part of CISA's list of Known Exploited Vulnerabilities. Zyxel ATP, USG FLEX, VPN, and ZyWALL/USG firewalls allow for improper error message handling which could allow an unauthenticated attacker to execute OS commands remotely by sending crafted packets to an affected device.
The following remediation steps are recommended / required by June 21, 2023: Apply updates per vendor instructions.
Vulnerability Analysis
CVE-2023-28771 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. This vulnerability is known to be actively exploited by threat actors in an automatable fashion. The potential impact of an exploit of this vulnerability is considered to be critical as this vulnerability has a high impact to the confidentiality, integrity and availability of this component.
Weakness Type
What is a Shell injection Vulnerability?
The software 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 when it is sent to a downstream component.
CVE-2023-28771 has been classified to as a Shell injection vulnerability or weakness.
Affected Versions
Zyxel ZyWALL/USG series firmware:- Version 4.60 through 4.73 is affected.
- Version 4.60 through 5.35 is affected.
- Version 4.60 through 5.35 is affected.
- Version 4.60 through 5.35 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.