Urgent: External Login plugin (≤ 1.11.2) — Unauthenticated SQL Injection (CVE-2025-11177) and what site owners must do now

Date: 15 October 2025
Severity: High (CVSS 9.3)
Affected software: External Login WordPress plugin, versions ≤ 1.11.2
Vulnerability type: Unauthenticated SQL injection via plugin logging input (log parameter)
Fixed version: N/A (no official patch available at time of writing)

From my experience as a Hong Kong-based security practitioner working on web application protection, I need to be direct: an unauthenticated SQL injection in an authentication-related plugin is one of the most serious issues you can face. Because the vulnerable code path requires no authentication, any remote attacker can attempt to execute SQL against your database. This may lead to data theft, privilege escalation, persistent backdoors, and full site takeover. The CVE for this issue is CVE-2025-11177. At the time of publication, no official fix has been released by the plugin author.

This article covers:

• What the vulnerability is and why it is dangerous
• How to check whether your site is affected
• Immediate mitigations (short-term and intermediate)
• Detection and forensic steps if compromise is suspected
• Virtual patching with a Web Application Firewall (WAF) — how it helps and practical rule examples
• Long-term hardening and remediation

Executive summary (for site owners and administrators)

• Vulnerability: An unauthenticated SQL injection via plugin logging input (a “log” parameter or an endpoint that writes/processes logs) exists in External Login (≤ 1.11.2).
• Impact: Remote attackers can inject SQL without credentials — read/modify data, create admin accounts, install backdoors.
• Risk: Very high. Exploitable over the internet. Expect scanning and automated exploitation attempts.
• Immediate actions: If the plugin is installed, remove or deactivate it immediately. If removal is not possible, block access to the plugin via server rules or deploy WAF rules to block the exploit pattern. Monitor logs for indicators of compromise.
• Hosts/manage-many-sites: Treat this like an incident — notify customers, block plugin paths at the web layer, and deploy virtual patches host-wide where practical.

What is the vulnerability (plain language)

The plugin accepts input intended for logging but fails to sanitise or parameterise that input before incorporating it into SQL. Because the vulnerable code path is reachable without authentication, an unauthenticated attacker can craft payloads that change the structure of the SQL query. Result: SQL injection.

Possible consequences:

• Extract sensitive data: usernames, emails, password hashes, API keys
• Modify data: change user roles, create admin accounts
• Install backdoors or malicious content
• Corrupt or delete tables
• Pivot to other systems if credentials are exposed

Why unauthenticated SQL injection is a top-tier emergency

“Unauthenticated” means no valid WordPress account is needed. That makes exploitation trivially scriptable and attractive to malicious actors and botnets. At CVSS 9.3, the severity is near critical. The vulnerability threatens confidentiality and integrity; every hour without mitigation increases the risk of compromise.

How to quickly determine if your site is affected

1. WordPress admin check (fast):

   Log in to wp-admin → Plugins → look for “External Login.” If version ≤ 1.11.2, you are affected.

2. WP-CLI (safe, for admins/hosts):

   wp plugin list --format=table

   To deactivate quickly:

   wp plugin deactivate external-login

   To remove:

   wp plugin delete external-login

3. Filesystem check:

   Look for the plugin directory:

   /wp-content/plugins/external-login/

   Note: some sites rename plugin folders — check plugin headers or search for files containing “external-login”.

4. Remote scan / logs:

   Search access logs or vulnerability scanner output for requests against the plugin path or requests containing SQL tokens (UNION, SELECT, SLEEP, etc.).

If the plugin is present, act immediately.

Immediate mitigation options — do this now (ordered by priority)

1. Deactivate and uninstall the plugin (recommended)

   If the plugin is not business-critical, deactivate and delete it. This removes the attack surface.

   wp plugin deactivate external-login && wp plugin delete external-login

2. If you cannot remove the plugin, restrict access to its files

   Implement a server-level block on the plugin directory as a temporary kill-switch.

   Apache (.htaccess inside plugin folder):

   <IfModule mod_authz_core.c>
     Require all denied
   </IfModule>
   <IfModule !mod_authz_core.c>
     Deny from all
   </IfModule>

   Nginx (example):

   location ^~ /wp-content/plugins/external-login/ {
       deny all;
       return 403;
   }

   Test carefully to ensure you do not break essential site functionality.

3. Block exploit patterns with a WAF (virtual patching)

   Deploy rules that target SQL-injection patterns and the plugin’s URL patterns. This prevents malicious traffic reaching the vulnerable code while you wait for an official fix.

4. Server-level request filtering

   Drop requests that show obvious SQL payload patterns. Example ModSecurity rules (tune to your environment):

   SecRule REQUEST_URI "@beginsWith /wp-content/plugins/external-login/" "id:1009001,phase:1,deny,log,msg:'Blocked request to External Login plugin directory'"
   SecRule ARGS_NAMES|ARGS|REQUEST_URI|REQUEST_BODY "(?i:(\bunion\b|\bselect\b|\binformation_schema\b|\bbenchmark\b|\bsleep\s*\(|\bload_file\b|\binto\s+outfile\b))" "id:1009002,phase:2,deny,log,msg:'SQLi pattern detected, blocked'"

   These are broad; tune to reduce false positives.

5. Harden database privileges (intermediate)

   Ensure the DB user has least privilege. This does not prevent SQLi, but can limit some post-exploitation actions (e.g., FILE or SUPER operations).

6. Snapshot and backup

   Take an offline, trusted backup of files and database now for forensics. Preserve pre-mitigation state where possible.

Recommended WAF signatures and examples (practical)

Virtual patching aims to stop malicious input from reaching the vulnerable code. Below are example rules you can adapt to your stack.

Nginx (block plugin URI + suspicious query strings)

# Block suspicious SQL-like query strings to the External Login plugin
location ~* /wp-content/plugins/external-login/ {
    if ($args ~* "(union|select|information_schema|sleep\(|benchmark\(|load_file|into outfile|\bor\s+1=1\b)") {
        return 403;
    }
    # Optionally deny any requests to plugin directory entirely:
    return 403;
}

Apache mod_rewrite (.htaccess in site root)

<IfModule mod_rewrite.c>
  RewriteEngine On
  # Block SQLi-like requests targeting the plugin folder
  RewriteCond %{REQUEST_URI} ^/wp-content/plugins/external-login/ [NC,OR]
  RewriteCond %{QUERY_STRING} (union|select|information_schema|sleep\(|benchmark\(|load_file|into%20outfile|or%201=1) [NC]
  RewriteRule .* - [F,L]
</IfModule>

ModSecurity (high-level)

SecRule REQUEST_URI "@beginsWith /wp-content/plugins/external-login/" "id:1209001,phase:1,deny,log,msg:'Block access to external-login plugin'"
SecRule ARGS|REQUEST_URI|REQUEST_HEADERS "(?i:\b(union|select|information_schema|load_file|into\s+outfile|benchmark|sleep)\b)" "id:1209002,phase:2,deny,log,msg:'Possible SQLi attempt - blocked'"

Generic WAF rule text

Condition:
  - Request path contains "/wp-content/plugins/external-login/" OR request contains parameter named "log"
AND
  - Request body or query string contains SQL keywords/patterns: union, select, information_schema, sleep(, benchmark(, load_file, into outfile, or 1=1, concat(
Action: Block (403), Log, Alert admin

Tune rules to the level of traffic you see. On high-traffic sites with free-form user input, narrow rules to plugin paths + SQL tokens to reduce false positives.

Detection and signs of compromise

If the plugin was accessible before mitigation, assume probing or exploitation attempts occurred. Look for these indicators:

• Database errors or unusual SQL-related error messages in logs
• New or unexpected administrator users in wp_users or wp_usermeta:

  SELECT ID, user_login, user_email, user_registered FROM wp_users ORDER BY user_registered DESC LIMIT 20;

• Unexpected outbound network connections from the web server (webshell callbacks)
• Files added to wp-content/uploads or other writable directories you did not create
• Modification timestamps on core/theme/plugin files that don’t match update activity
• Access logs showing SQL tokens (UNION, SELECT, SLEEP, INFORMATION_SCHEMA):

  grep -E "(UNION|SELECT|INFORMATION_SCHEMA|SLEEP|benchmark|load_file|into outfile)" /var/log/apache2/access.log

• WordPress debug logs showing SQL errors (if WP_DEBUG logging was enabled)
• Unexpected redirects, spam pages, or content injections

If any signs are present, treat it as a potential compromise and follow incident response steps below.

Incident response checklist (if you suspect exploitation)

1. Isolate the site: Put into maintenance mode; block traffic except from known admin IPs or take offline.
2. Preserve evidence: Export webserver logs, database snapshot, and plugin/theme files to secure storage. Do not overwrite or truncate logs.
3. Perform a malware scan: Use trusted tools and, if possible, perform offline scanning.
4. Look for persistence: Search for webshells, modified cron entries, or rogue admin users. Preserve artifacts before removal.
5. Rotate credentials: Change WordPress admin passwords, database passwords, SFTP/FTP credentials, and API keys. Note that rotation does not undo past data theft.
6. Rebuild from clean backups: If compromise is confirmed, rebuild from a known-good backup taken before the intrusion, then reapply mitigations.
7. Post-incident analysis: Conduct root cause analysis and document findings and remediation steps.

If you manage many sites or are a host, notify affected customers and provide clear remediation instructions.

Long-term remediation and hardening

• Keep WordPress core, themes, and plugins updated. Subscribe to reliable vulnerability feeds.
• Limit plugin usage and vet plugins periodically.
• Apply least-privilege to the database user.
• Restrict admin endpoints with IP allow-lists and enforce two-factor authentication (2FA) for administrators.
• Use virtual patching at the edge (WAF rules) while vendors address vulnerabilities.
• Implement file integrity monitoring to detect unauthorized changes.
• Enable logging and retention for access, application, and firewall logs.
• Maintain regular, tested backups stored off-site.

Why virtual patching matters here

When a high-severity vulnerability is disclosed and no vendor patch is available, virtual patching at the web layer is the fastest practical protection. Blocking exploit vectors before they hit the vulnerable code can prevent mass exploitation while waiting for an official, tested patch.

Benefits of virtual patching:

• Immediate protection without modifying plugin code
• Centralised rules that can protect multiple sites quickly
• Buys time for thorough testing and for the vendor to release a correct fix

Practical advice for hosting providers and agencies

• Block the plugin path globally at the host level if you observe scanning or exploitation attempts across customers.
• Provide customers simple remediation steps (WP-CLI commands, admin instructions).
• Offer cleanup and credential rotation assistance for infected sites.
• Deploy host-level WAF rules and virtual patches to protect all customer sites immediately.
• Communicate clearly and promptly with customers: describe risk, actions taken, and required customer steps.

Detection queries and forensic starting points (for security teams)

Useful queries and commands to triage and investigate:

-- Recent users (look for new admins)
SELECT ID, user_login, user_email, user_registered FROM wp_users WHERE user_registered > DATE_SUB(NOW(), INTERVAL 30 DAY);
SELECT * FROM wp_usermeta WHERE meta_key LIKE '%capabilities%';

-- Suspicious options or cron entries
SELECT option_name, option_value FROM wp_options WHERE option_name LIKE '%cron%' OR option_name LIKE '%active_plugins%';

-- Find recent files in uploads
find /var/www/html/wp-content/uploads -type f -mtime -30 -print

-- Search for eval usage
grep -R "eval(" /var/www/html/wp-content/ | head

-- Scan access logs for SQLi indicators
grep -E "union|select|benchmark|sleep|information_schema|load_file|into outfile" /var/log/nginx/access.log /var/log/apache2/access.log

These are starting points. If you see evidence of compromise, engage a professional incident response team immediately.

Communications checklist (what to tell stakeholders)

When informing stakeholders, include:

• What happened (high-level) and the assessed risk (unauthenticated SQLi — high)
• Actions already taken (plugin removed/blocked, WAF rules applied)
• Next steps (forensics, clean-up, credential rotation)
• Actions requested of the customer (change passwords, check site functionality, report anomalies)
• Expected timeline and follow-ups

Frequently asked questions

Q: If I remove the plugin, am I safe?

A: Removing the plugin removes that attack surface. However, if exploitation occurred prior to removal, persistent backdoors may already exist. Always scan and review logs before declaring a site clean.

Q: Does rotating database credentials help?

A: Rotation is essential after confirmed compromise to prevent further access. It does not undo any data exfiltration that already occurred.

Q: Will a WAF slow my site down?

A: Properly configured WAFs have minimal performance impact compared to the protection they provide. The trade-off is usually acceptable for high-risk vulnerabilities.

Q: What about plugin updates?

A: When the plugin vendor publishes a fix, apply it immediately. Virtual patches are temporary; official patches are the long-term solution.

What to do right now — action checklist for the next 60 minutes

1. Check if External Login is installed and note the version.
2. If non-critical, deactivate and delete the plugin.
3. If deletion is not possible:
   • Put plugin folder behind deny-all webserver rules, or
   • Deploy WAF rules to block SQLi patterns targeting the plugin.
4. Snapshot database and filesystem for investigation.
5. Search for anomalous admin accounts and suspicious logs.
6. Rotate admin and DB credentials if compromise is suspected.
7. Monitor logs for SQLi signatures and evidence of exploitation.
8. Apply long-term hardening steps: least privilege, backups, logging, WAF.

Final thoughts from a Hong Kong security expert

This External Login vulnerability is particularly dangerous because it is remote, unauthenticated, and impacts authentication flows. Attackers will prioritise it. If you host WordPress sites or manage client sites, act now: either remove the plugin or place immediate protections at the edge (virtual patches and server-level blocks). If you suspect compromise, preserve evidence and perform a full incident response.

In Hong Kong’s busy hosting and web environment, rapid, decisive action reduces reputational and data risk. If you require assistance, engage an experienced incident response provider or security consultancy to implement mitigations and conduct a full investigation.

Stay alert, act quickly, and document every step.