What is the Japanese keyword hack? How to detect and fix it

Japanese keyword hack can silently infect a website and flood Google search results with spam pages that have nothing to do with the original content. The attack mainly targets vulnerable WordPress websites, using hidden malware and SEO spam techniques to manipulate search rankings and redirect traffic to malicious pages.

If your website suddenly shows Japanese characters in search results or indexed URLs you never created, immediate action is necessary. In this article, we will help you understand how the Japanese keyword hack works, the warning signs to look for, and how to clean and secure your website properly.

What is the Japanese keyword hack?Link to heading

The Japanese keyword hack is a form of SEO spam in which attackers exploit weaknesses in your website, most commonly vulnerabilities tied to SEO-related functionality. They inject hidden Japanese text, spammy keywords, or manipulated content directly into your pages, posts, or metadata, using your site's existing authority to push their own content up the search rankings.

This attack goes by several names, including "Japanese SEO spam" and "SEO poisoning". It operates on the same principle as the pharma hack, a well-documented attack where criminals hijack legitimate websites to promote counterfeit products, grey-market goods, or other content that would never pass Google's advertising or search policies.

The most disorienting aspect of this hack is its invisibility. Your regular visitors see nothing wrong. The malicious content is served selectively to search engine crawlers, not humans, which means the damage accumulates quietly in the background. Over time, your SEO performance deteriorates, your domain loses credibility, and you risk receiving a manual penalty, or outright removal, from Google's index.

Key signs of the Japanese keyword hackLink to heading

Knowing what to look for is the first step toward protecting your site. Several warning signs indicate your website may have been compromised by the Japanese keyword hack.

The most obvious symptom is the sudden appearance of pages you never created. These auto-generated pages are filled with Japanese text, housed under randomly named directories, and stuffed with affiliate links pointing to suspicious online stores. If these pages get indexed by Google, they will surface in search results under your domain, directly damaging your brand's reputation with every impression.

A less visible but equally serious warning sign is unauthorized access to your Google Search Console account. Hackers frequently add themselves as verified property users, which gives them the ability to alter critical settings such as geotargeting preferences and sitemap submissions. Reviewing your verified users regularly and revoking access for any accounts you don't recognize is an essential part of keeping your Search Console secure.

You should also run a check through the Security Issues report inside Google Search Console, located under Security and Manual Actions. This report flags pages on your site that Google has identified as hacked or compromised, giving you a direct view of the damage from the search engine's perspective.

Additional symptoms include garbled or nonsensical content appearing when you follow links to affected pages, as well as unexpected redirects to third-party websites. In some cases, hackers will deliberately trigger fake 404 errors on compromised pages to mislead you into thinking the problem no longer exists, when in fact the malicious content is still live and indexed.

To check for cloaking, the technique used to show different content to search engines versus real visitors, use the URL Inspection tool in Google Search Console. The Fetch as Google feature within this tool renders a page exactly as Googlebot sees it, which can expose hidden content that would never appear during a normal browser visit.

Finally, audit your indexed pages by running a site:yourdomain.com search directly in Google. Review the results carefully for pages with unusual URLs, Japanese characters in titles or descriptions, or directories you do not recognize. If Google returns clean results, repeat the same search on Bing and other search engines, as indexation timing can vary. 

Any result that looks out of place is a signal to investigate immediately and take action to secure your site.

How to remove the Japanese keyword hackLink to heading

Step 1: Back up everything before you touch anythingLink to heading

Before making a single change, create a full offline backup of your website, all server files and your database. This is non-negotiable. If something goes wrong during cleanup, a backup is the only thing standing between you and a broken site. Search for backup instructions specific to your CMS (WordPress, Joomla, Drupal, etc.) to find the right method.

Step 2: Remove unauthorized users from Google Search ConsoleLink to heading

Hackers routinely add themselves as verified owners of your Search Console property. This gives them persistent control over your site's SEO settings even after you've cleaned the files.

Go to your Search Console verification page, click "Verification Details," and review every verified user. Remove any account you don't recognize immediately.

After revoking access, you must also delete the verification token they used, otherwise their access can be reinstated. There are two token types to look for:

• An HTML file sitting in the root directory of your site
• A rewrite rule inside your .htaccess file that looks like this:

RewriteEngine On
RewriteRule ^google(.*)\.html$ dir/file.php?google=$1 [L]

To confirm the token has been successfully removed, visit a URL in this format: yourdomain.com/google1234.html. If it returns a 404 error, the dynamically generated token is gone.

Step 3: Clean or replace your .htaccess fileLink to heading

The .htaccess file is a frequent target of the Japanese keyword hack. Hackers modify it to redirect visitors, generate spammy pages, or create fake verification tokens.

Find all .htaccess files on your server, there may be more than one, and they are often hidden files, so make sure hidden files are visible in your file manager or FTP client.

Replace every .htaccess file with a clean default version. Search for "default .htaccess file" plus your CMS name to find the correct version. If your site has never used a custom .htaccess and no default version exists, the file you found is almost certainly malicious, save a copy offline for reference and delete it from the server.

Step 4: Reinstall your CMS core files, themes, and pluginsLink to heading

Reinstalling the core files of your CMS overwrites any injected code hiding inside default files. Download a fresh copy of your CMS and replace the existing core files on your server. Do the same for every theme and plugin. Even a single outdated or compromised plugin can reintroduce the hack. This step eliminates a large portion of the infected files in one move.

One important caution: reinstalling core files can overwrite customizations you've made directly to those files. Back up your database and all files before you proceed.

Step 5: Find and remove malicious PHP filesLink to heading

Reinstalling core files won't catch everything. Hackers often plant additional rogue PHP files in non-standard locations. Work through these files systematically:

• Compare your server files against the default file list for your CMS. Any PHP file that doesn't belong to the original CMS installation or your legitimate plugins is suspicious.
• Sort files by date last modified. Focus on files changed around the time you first noticed the hack.
• Sort files by size. Unusually large files often contain injected code.

Pay special attention to these commonly targeted files: index.php, wp-load.php, 404.php, and view.php.

Once you have a list of suspicious files, open them and look for obfuscated code, blocks of scrambled characters typically preceded by PHP functions like base64_decode, eval, rot13, strrev, or gzinflate. This code is often compressed into a single long line to disguise its size. If you find it, the file is infected and must be cleaned or deleted.

Step 6: Audit and clean your sitemapsLink to heading

As part of executing the Japanese keyword hack, attackers frequently modify your sitemap or inject entirely new ones to get their spam URLs indexed by Google as fast as possible.

Open your existing sitemap and scan every URL. Remove any links that don't correspond to real pages on your site. If you find sitemap files you never created yourself, check their contents, if they contain only spam URLs, delete the files entirely.

Step 7: Verify your site is cleanLink to heading

Once all malicious files have been removed, confirm the cleanup worked. Return to Google Search Console and use the URL Inspection tool on the spam pages you identified earlier. If they return a "Not Found" status, your cleanup has been successful.

If any spam pages still appear as indexed, use the URL Removal tool in Search Console to expedite their removal from Google's index. Submit your clean sitemap to signal to Google that your site has been restored.

Step 8: Submit a reconsideration request to GoogleLink to heading

If Google issued a manual penalty against your site as a result of the hack, you must formally notify them that the issue has been resolved. Go to Security and Manual Actions in Google Search Console, open the relevant report, and submit a reconsideration request explaining the steps you took.

Google will review your site and, once satisfied, lift the penalty. Ranking recovery typically follows within days to a few weeks depending on how long the hack was active.

What to do after resolving the hackLink to heading

Once the Japanese keyword hack has been fully removed, your next priority is restoring your site's standing with both search engines and your audience. If Google flagged your domain for malicious activity during the attack, you must submit a reconsideration request through the Security Issues report in Google Search Console. 

This formally notifies Google that the problem has been identified and resolved, and prompts them to re-evaluate your site for reinstatement.

From there, shift your focus to rebuilding your SEO. Audit all affected metadata, sitemaps, and canonical tags to confirm they are accurate and aligned with current best practices. Resubmit your XML sitemap through Google Search Console to prompt search engines to recrawl your site, reindex your legitimate pages, and begin restoring the organic traffic lost during the attack. Recovery takes time, but these steps put the process in motion.

How to prevent the Japanese keyword hack in the futureLink to heading

Cleaning up after a hack is reactive. What protects your site long-term is a consistent, proactive security routine. The following practices significantly reduce your exposure to the Japanese keyword hack and similar SEO spam attacks.

• Keep WordPress, themes, and plugins updated at all times. Software updates exist primarily to patch known security vulnerabilities. Running outdated versions is one of the most common reasons sites get compromised in the first place.
• Use strong, unique passwords across every account connected to your site, including WordPress admin, FTP, hosting, and database credentials. Never reuse passwords across different platforms. A password manager makes this practical without sacrificing security.
• Enable two-factor authentication on your WordPress admin login and any other sensitive account. Even if a password is compromised, 2FA blocks unauthorized access by requiring a second form of verification.
• Install a Web Application Firewall. Tools like Wordfence, Sucuri, or iThemes Security intercept and filter malicious traffic before it ever reaches your site, blocking harmful requests at the perimeter rather than after the damage is done.
• Limit login attempts using a dedicated plugin. Brute-force attacks, where automated tools cycle through thousands of password combinations, are a common entry point for hackers. Restricting the number of failed login attempts shuts this vector down.
• Set up automated, scheduled backups stored in a location completely separate from your hosting environment. In a worst-case scenario, a clean recent backup is what allows you to recover quickly without starting from scratch.
• Configure correct file permissions across your WordPress installation. Sensitive files and directories should never have unnecessary write permissions. Overly permissive file settings are an open invitation for injected code.
• Monitor your site continuously for unusual activity, unexpected spikes in traffic, unfamiliar file modifications, or new user accounts you didn't create. A real-time security plugin can surface these anomalies before they escalate into a full breach.
• Audit your installed themes and plugins regularly and remove anything that is no longer actively used. Every unused plugin or theme sitting dormant on your server is an unmonitored attack surface. If you are not using it, delete it entirely.
• Review user roles and permissions on a routine basis. Access should always be limited to what each user genuinely needs to do their job. Revoke permissions for anyone who no longer requires access, and ensure no account holds more privilege than necessary. The fewer points of entry available to an attacker, the more difficult your site is to compromise.

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ConclusionLink to heading

Japanese keyword hack can quickly turn a trusted website into a source of spam in Google's search results if the infection is ignored for too long. That is why removing the malware completely and closing every possible security gap should always be treated as a priority.

Once your website is clean, ongoing security maintenance becomes just as important as the initial recovery. A proactive approach to website security is ultimately the best defense against SEO spam and hidden malware infections.