Table des matières

• Qu'est-ce que l'inclusion de fichiers locaux (LFI) ?
• Why LFI in WordPress themes is especially risky
• What we know about the Yokoo LFI (CVE-2025-69400)
• How an attacker would typically abuse this LFI (conceptual)
• Détection et indicateurs de compromission (IoCs)
• Immediate mitigations and virtual patching (urgent steps)
• Secure coding patterns to eliminate LFI
• Hardening and recovery after suspected compromise
• Longer-term prevention and monitoring recommendations
• Practical 24-hour checklist

Qu'est-ce que l'inclusion de fichiers locaux (LFI) ?

Local File Inclusion is a vulnerability class where unsanitised input is used to include files on the server. In PHP, unsafe patterns often look like:

include( $_GET['template'] );

If an attacker controls the filename being included, they can read local files (wp-config.php, /etc/passwd), leak secrets, or in some environments chain LFI to remote code execution by including attacker-controlled files (logs, uploads containing injected PHP).

The combination of unauthenticated access and dynamic template loading in themes makes LFI in WordPress themes particularly dangerous.

Why LFI in WordPress themes is especially risky

• Themes execute with the web server user’s privileges; reading theme files can reveal configuration and credentials.
• wp-config.php contains DB credentials and salts — disclosure often leads to database compromise.
• In some hosting setups, LFI can be chained to code execution via logs or uploaded artifacts.
• Many WordPress sites reuse credentials or share hosts; a single disclosure may cascade.
• LFI is often exploitable without authentication, enabling mass scanning and automated exploitation.

What we know about the Yokoo LFI (CVE-2025-69400)

• Affected software: Yokoo WordPress theme, versions ≤ 1.1.11.
• Vulnerability: Local File Inclusion (LFI).
• CVE identifier: CVE-2025-69400.
• Exploitation: Unauthenticated — no WordPress credentials required.
• Severity: High (CVSS 8.1).
• Fix status at disclosure: vendor patch may be pending for some installs — treat as high priority and apply mitigations immediately.

Point clé : If you run Yokoo ≤ 1.1.11, assume risk and act now to reduce exposure.

How an attacker would typically abuse this LFI (conceptual)

1. Discover a vulnerable endpoint that includes a file path based on user input.
2. Send requests attempting path traversal (../ or encoded variants) to include sensitive files.
3. If successful, the server returns file contents (configuration, source code) or processes the file in a way that leaks secrets.
4. With credentials or keys, the attacker can access the database, create admin users, or pivot to other systems.
5. In some configurations, attackers include log or upload files containing PHP and trigger execution, achieving remote code execution (RCE).

Because exploitation is unauthenticated, attackers automate scanning across many sites — rapid detection and virtual patching reduce exposure to mass exploitation.

Détection et indicateurs de compromission (IoCs)

Prioritise these checks if you run Yokoo:

1. Web server and application logs
   • Look for requests to theme paths where parameters include path traversal sequences (../ or URL-encoded variants).
   • Search for query strings referencing wp-config.php, .env, /etc/passwd, or other sensitive filenames.
   • Detect spikes in unusual requests or increased 4xx/5xx responses targeting theme files.
2. Site behaviour
   • Responses that suddenly include file contents (PHP source, DB connection strings).
   • Injected scripts, unexpected page content, or altered theme templates.
3. WordPress admin and database
   • Unknown admin users, unexpected plugins, or modified plugin/theme timestamps.
   • High DB load or unfamiliar database queries.
4. Filesystem and PHP execution
   • New PHP files in uploads, cache directories, or other writable paths.
   • Modified files under wp-content, themes, or plugins.
5. Outbound activity
   • Unusual outbound connections — data exfiltration or callbacks to control servers.

Examples of detection patterns for logs or WAF rules: query strings containing ../ or encoded traversal (%2e%2e%2f), or requests where REQUEST_URI or arguments mention wp-config.php, \.env, ou /etc/passwd. Use multiple signals — logs, file checks and behaviour — to confirm compromise.

Immediate mitigations and virtual patching (urgent steps)

If your site uses Yokoo ≤ 1.1.11, apply these prioritized actions now.

1. Put the site into maintenance mode (if practical). Limiting public access reduces automated scanning and exploitation while you apply mitigations.
2. Virtual patching via WAF or server rules (fastest mitigation).

   Implement rules that block path traversal and attempts to read sensitive filenames. Examples of defensive rule concepts (tune to your environment):

   SecRule REQUEST_URI|ARGS "@rx (\.\./|\%2e\%2e/|\%2e%2e)" "id:100001,phase:1,deny,log,msg:'Possible LFI path traversal attempt'"
   SecRule ARGS|REQUEST_URI "@rx (wp-config\.php|\.env|/etc/passwd)" "id:100002,phase:1,deny,log,msg:'Attempt to access sensitive file'"
   
   # Nginx example (conceptual)
   if ($request_uri ~* "\.\./|%2e%2e") {
     return 403;
   }

   Restrict these rules to requests targeting theme endpoints where the vulnerable include happens to reduce false positives. Virtual patching buys time until the theme is updated or removed.

3. Disable or switch the theme. If feasible, switch to a default WordPress theme or a known-good theme temporarily. If the vulnerable theme is business-critical and cannot be disabled, ensure WAF rules are in place and limit access to known IPs if possible.
4. Restrict direct access to theme PHP files. Add server-level restrictions to deny direct HTTP access to include files that should not be requested. Example Apache snippet (apply only where safe and tested):

<FilesMatch "\.php$">
  Require all denied
</FilesMatch>

5. Tighten file permissions. Assurez-vous wp-config.php is not world-readable and is owned by the correct user. Limit writable directories to those strictly required (uploads, cache).
6. Scanner pour des compromissions. Run a full malware and file integrity scan of filesystem and database. Look for webshells, unknown PHP files, and backdoors. If compromise is suspected, isolate the server and follow recovery steps below.
7. Faites tourner les identifiants. Si wp-config.php or DB credentials may have been exposed, rotate database passwords, API keys, and WordPress salts immediately. Update any external services that used the same credentials.
8. Backups and preserve evidence. Preserve current backups and logs for forensic analysis. If restoring, choose a backup from before the earliest sign of compromise and ensure the vulnerability is addressed before bringing the site back online.
9. Monitor aggressively. Increase log retention and alerting. Use IDS/WAF alerts to detect attempts in real time and keep heightened monitoring for at least 90 days after remediation.

Note: if you already use a managed firewall or host-provided security controls, enable and verify rules that block path traversal and file access attempts. Tune rules to avoid business disruption.

Secure coding patterns to eliminate LFI

If you develop themes or custom templates, adopt these patterns:

1. Avoid including filenames directly from user input; never call inclure/exiger with raw GET/POST/Cookie values.
2. Use whitelists for template loading — map allowed template identifiers to known file paths:

// Allowed templates map
$allowed_templates = [
    'home'    => 'templates/home.php',
    'product' => 'templates/product.php',
    'list'    => 'templates/list.php',
];

$t = isset($_GET['t']) ? $_GET['t'] : 'home';
if (isset($allowed_templates[$t])) {
    include get_template_directory() . '/' . $allowed_templates[$t];
} else {
    include get_template_directory() . '/templates/404.php';
}

3. Validate and normalise paths. Utilisez realpath(), basename() and confirm the resolved path is within the expected theme directory before including:

$requested = $_GET['file'] ?? '';
$base_dir = realpath(get_template_directory() . '/templates');

$target = realpath($base_dir . '/' . $requested);
if ($target && strpos($target, $base_dir) === 0 && is_readable($target)) {
    include $target;
} else {
    http_response_code(404);
    exit;
}

4. Minimise PHP execution in user-writable directories — deny execution in uploads and cache folders where possible.
5. Apply principle of least privilege — code that reads files should only have read access to what it needs.

Hardening and recovery after suspected compromise

If you discover evidence of successful exploitation, follow a damage-limitation and recovery process:

1. Isolez le site. Take affected services offline or block suspicious IP ranges. Preserve all logs and backups for forensic analysis.
2. Faites tourner les secrets. Change DB passwords, WordPress salts, SSH/FTP credentials, and reissue API keys.
3. Clean or restore. Prefer restoring from a clean backup taken before the compromise. If restoring is not possible, perform a full forensic cleanup: identify and remove backdoors, replace modified files with clean copies from trusted sources, and harden permissions.
4. Reinstall and patch. Replace vulnerable theme files with vendor-patched versions once available. If no patch exists, keep virtual patches in place and consider removing the theme.
5. Audit and strengthen. Conduct a post-mortem to identify control failures and improve processes: OS patches, PHP hardening, logging and alerting.
6. Informez les parties prenantes. If personal or payment data may have been exposed, follow legal and contractual obligations for disclosure and notify affected parties as required.
7. Monitor for follow-up attacks. Attackers often attempt to regain access — maintain elevated monitoring for at least 90 days.

Longer-term prevention and monitoring recommendations

• Keep WordPress core, themes, and plugins updated. Test and deploy vendor patches promptly.
• Maintain regular, verified off-site backups and document restore procedures.
• Enforce least-privilege for file and DB users; use separate DB users per site where possible.
• Use a managed Web Application Firewall (WAF) or host-provided controls capable of virtual patching uncommon attack patterns and delivering rapid rule updates.
• Mettez en œuvre une surveillance de l'intégrité des fichiers pour détecter les changements inattendus.
• Enable multi-factor authentication for administrators and minimise the number of admin accounts.
• Limit PHP execution in uploads and other writable folders.
• Require security reviews for custom themes and plugins before production deployment.

Practical checklist you can act on in the next 24 hours

1. If you run Yokoo ≤ 1.1.11:
   • Enable maintenance mode (if possible).
   • Activate WAF or server rules blocking path traversal and attempts to read sensitive filenames.
   • Temporarily disable the Yokoo theme or switch to a default theme if feasible.
2. Immediately scan:
   • Run a complete malware/file scan of files and database.
   • Search access logs for traversal patterns and attempts to access wp-config.php or other sensitive files.
3. Review and protect sensitive files:
   • Vérifiez wp-config.php permissions and location.
   • Deny PHP execution in uploads and other writable directories.
4. Rotate credentials if exposure is suspected.
5. Preserve backups and logs for forensic analysis and restore from a known-clean backup if needed.
6. Augmentez la surveillance et la conservation des journaux pendant au moins 90 jours.

Dernières réflexions

LFI issues are among the most critical vulnerabilities because they can expose secrets and enable further compromise. When an unauthenticated LFI appears in a widely distributed theme, speed matters: automated scanners and opportunistic attackers scan the web continuously.

If your team cannot immediately audit and patch theme code, virtual patching via WAF/server rules, disabling the vulnerable theme, and following the procedural steps above will reduce risk while you remediate.

If you need professional assistance, engage a qualified security professional or an incident response team to help with detection, rule tuning, forensic analysis, and safe recovery.