CVE-2022-0342 in USG
Summary
by MITRE • 03/28/2022
An authentication bypass vulnerability in the CGI program of Zyxel USG/ZyWALL series firmware versions 4.20 through 4.70, USG FLEX series firmware versions 4.50 through 5.20, ATP series firmware versions 4.32 through 5.20, VPN series firmware versions 4.30 through 5.20, and NSG series firmware versions V1.20 through V1.33 Patch 4, which could allow an attacker to bypass the web authentication and obtain administrative access of the device.
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Analysis
by VulDB Data Team • 03/31/2022
The vulnerability identified as CVE-2022-0342 represents a critical authentication bypass flaw affecting multiple Zyxel network security device series including USG, ZyWALL, USG FLEX, ATP, VPN, and NSG platforms. This issue stems from improper validation within the Common Gateway Interface (CGI) program component of affected firmware versions, creating a pathway for unauthenticated attackers to escalate privileges and gain administrative control over impacted devices. The vulnerability specifically affects firmware versions ranging from 4.20 through 4.70 for USG/ZyWALL series, 4.50 through 5.20 for USG FLEX series, 4.32 through 5.20 for ATP series, 4.30 through 5.20 for VPN series, and V1.20 through V1.33 Patch 4 for NSG series, indicating a widespread impact across Zyxel's security portfolio.
The technical root cause of this vulnerability lies in the CGI program's insufficient input validation and authentication mechanisms that fail to properly verify user credentials before granting administrative access. When an attacker exploits this flaw, they can bypass the standard web authentication process and directly access the device's administrative interface without requiring valid credentials. This represents a fundamental breakdown in the device's security architecture where the authentication layer becomes ineffective, allowing unauthorized access to critical system functions including configuration changes, user management, and network policy modifications. The vulnerability operates at the application layer and can be classified under CWE-287, which addresses improper authentication issues, while also aligning with ATT&CK technique T1078 for valid accounts and T1566 for credential harvesting.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it provides attackers with complete administrative control over affected network devices. Once compromised, attackers can modify firewall rules, configure network settings, establish backdoors, and potentially use the device as a pivot point for lateral movement within the network infrastructure. The implications are particularly severe for organizations relying on Zyxel devices for perimeter security, as these devices often serve as critical gateways controlling network traffic flow and enforcing security policies. The vulnerability's widespread nature across multiple device series means that organizations with heterogeneous network environments may face cascading security risks, where a single compromised device could provide attackers with access to multiple network segments.
Organizations should immediately implement mitigation strategies including firmware updates to the latest available versions that address this authentication bypass vulnerability. Network segmentation and monitoring should be enhanced to detect unusual administrative access patterns, while access controls should be reviewed to ensure that only authorized personnel can access device management interfaces. Security teams should also consider implementing additional authentication layers such as two-factor authentication where possible, and conduct comprehensive vulnerability assessments to identify any other potential entry points within their network infrastructure. The remediation process should include thorough testing of updated firmware to ensure that the patch does not introduce compatibility issues with existing network configurations, while also validating that the authentication mechanisms function properly after the update process.