Japanese Keyword Hack in WordPress | Complete 2025 Removal & Prevention Guide

What Is the Japanese Keyword Hack?

The Japanese Keyword Hack, also known as the Japanese SEO Spam Hack, is a form of search engine cloaking where hackers inject Japanese language content and spammy links into your WordPress site often without altering the frontend you or your users see.

This hack exploits your website’s SEO reputation to:

• Insert fake Japanese e-commerce pages
  
• Redirect search engine traffic to spam or phishing stores
  
• Damage your search engine rankings and trustworthiness

How the Hack Works Behind the Scenes

This attack uses a multi-layered infection method:

Hackers may use obfuscated PHP functions (eval(), base64_decode, gzinflate, etc.) to hide malicious payloads.

Symptoms of the Japanese SEO Spam Hack

These are the most common indicators:

👁️ Visible Symptoms:

• Japanese characters or product listings (セール, 安い, etc.) appear in Google search results, but not on your actual pages.
  
• Search Console alerts: “Hacked content detected.”
  
• Your site title/meta in search appears in Japanese.
  
• Increased bounce rate from organic traffic.
  

🔍 Hidden Technical Signs:

• Fake pages like https://yoursite.com/セール-時計/ indexed by Google.
  
• New sitemap submitted (e.g., sitemap_japan.xml).
  
• Unknown users or plugins in WordPress admin.
  

Suspicious cron jobs or unfamiliar .php files in wp-content/uploads/.

Step-by-Step Guide: Removing the Japanese Keyword Hack

Step 1 – Scan Your Site (Externally & Internally)

External:

• Use Sucuri SiteCheck or VirusTotal to check indexed spam.
  

Check your site’s results on Google using:

site:yourdomain.com セール

site:yourdomain.com 時計

Internal:

• Install Wordfence or MalCare to scan core files and themes.
  

Use SSH or FTP to search for:

grep -r ‘base64_decode’ .

grep -r ‘eval(‘ .

Step 2 – Audit WordPress Files

Focus on:

• functions.php
  
• wp-config.php
  
• .htaccess
  
• Any unknown files in wp-content/uploads, wp-includes
  

🚨 Warning: Some malicious code is obfuscated or injected with whitespace or comments — don’t assume it’s safe because it “looks empty.”

Step 3 – Clean the Database

• Go to phpMyAdmin and search tables like:
  
  • wp_posts
    
  • wp_options
    
  • wp_users
    
• Look for Japanese terms, iframe injections, or base64-encoded content.
  

📌 Tip: Use SQL queries to speed this up:

SELECT * FROM wp_posts WHERE post_content LIKE ‘%iframe%’ OR post_content LIKE ‘%<script%’;

Step 4 – Remove Rogue Sitemaps & Reset .htaccess

• Look for fake sitemaps like:
  
  • /sitemap_japan.xml
    
  • /sitemap_index.xml (overwritten)
    
• Replace .htaccess with default WordPress version:
  

# BEGIN WordPress

<IfModule mod_rewrite.c>

RewriteEngine On

RewriteBase /

RewriteRule ^index\.php$ – [L]

RewriteCond %{REQUEST_FILENAME} !-f

RewriteCond %{REQUEST_FILENAME} !-d

RewriteRule . /index.php [L]

</IfModule>

# END WordPress

Step 5 – Re-secure and Re-submit to Google

• Delete any unknown admin users
  
• Change all admin passwords and salts
  
• Submit cleanup request via Google Search Console:
  
  • Use “Security Issues” tool
    
  • Submit reconsideration request if penalized
    
• Submit new, clean sitemap
  

How to Prevent the Japanese Keyword Hack (Permanently)

Tools to Help You

Final Thoughts: Don’t Just Clean — Fortify

The Japanese Keyword Hack is a SEO-driven cyberattack that often comes back if not completely cleaned. Many WordPress users remove the visible symptoms but leave behind backdoors, cron jobs, or fake admin accounts resulting in reinfection.

Cleaning it thoroughly means:

• Deep file and DB audits
  
• Resetting access credentials
  
• Fixing your SEO presence in Google
  

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