MyBB Documentation

Security Incident Response & Recovery

Recovering a Hacked or Compromised Forum

Numerous actions and conditions can leave web applications open to exploitation. These can be related to administrator errors (like misconfiguration and social engineering) or factors out of their control (like software vulnerabilities and external data breaches), and can occur even after following best security practices and recommendations.

Discover which components may be abused by attackers to run malicious code after gaining access, review common recovery steps, and learn how to respond to security incidents to protect your forum and users.

This article provides advice for most common setups, focusing on MyBB, and is intended for administrators with technical experience. Specific steps and their order may depend on configuration, incident circumstances and discovered evidence. It is generally recommended to contact a security professional familiar with modern web stack technology and refer them to this page to recover and secure impacted installations.


Unverified code and data should be considered quarantined and no interaction with them should take place. This establishes the following order of verification and recovery actions:

  1. administrators’ devices and personal accounts,
  2. domains, hosting accounts, reverse proxies, origin servers and additional infrastructure, TLS certificates,
  3. other installed applications/scripts,
  4. MyBB source code,
  5. MyBB stored data,
  6. MyBB upgrades,
  7. MyBB Admin CP’s internal verification tools,
  8. MyBB Settings and configuration,
  9. MyBB front-end templates,
  10. MyBB Extensions,

followed by remaining recovery operations. Elements and sections should not be used or accessed by anyone before they are verified as safe (e.g. forum pages should not be visited until MyBB code & data is reviewed and the board is upgraded).

All steps taken during the recovery process should be documented, including timestamps and signs & effects of suspicious activity. This information may be useful during investigation, consultation and help composing an incident report.

Whenever an SQL query is provided, we assume your table prefix is mybb_ — if you have a different table prefix, remember to replace it.


Restrict Access to the Forum

Access to a compromised forum should be disabled as soon as possible to reduce potential damage. This can be achieved by modifying the server configuration:

  • Apache 2.4 servers

    Add the following code in the .htaccess file in the MyBB root directory:

     Require all denied
     Require ip
  • Apache 2.2 servers

    Add the following code in the .htaccess file in the MyBB root directory

     Order deny,allow
     Deny from all
     Allow from
  • Nginx servers

    Add the following code to server block configuration for the forum:

     location / {
       deny all;

Replace with your IP address; if you find yourself unable to access your website during this process, it is possible that you have a dynamic IP, in which case you will have to repeat the above procedure whenever your IP changes.

You can also close the forum using the Board Closed setting. To avoid using the Admin CP:

  • execute the following SQL commands:
    UPDATE mybb_settings SET value = '1' WHERE name = 'boardclosed'; -- Close the board
    UPDATE mybb_settings SET value = '' WHERE name = 'boardclosed_reason'; -- Remove malicious "reason" content

    and delete the inc/settings.php file, or

  • in inc/settings.php, change the value of $settings['boardclosed'] to 1 (it will be reset if settings are rebuilt, e.g. by saving any setting in the ACP).


Create Copies

To help investigate the cause of the incident, create a backup of files, database, and servers (if feasible), and save any related logs (access log, error log, FTP log, etc.).

Identify Causes

To have a better understanding of what happened and what actions were performed, take time to review gathered logs to help establish a timeline of the attack and weaknesses leading to it, as well as attack artifacts, such as malicious data and file modifications. While the causes may be unrelated to the state of your MyBB installation, we recommend keeping affected websites offline until all potential problems are eliminated.

Mitigation & Recovery

Staff Devices and Accounts

It is possible that an administrator has downloaded something that infected their device(s) allowing the forum to be hacked, which makes it not safe to do anything else until it is 100% clean.

MyBB Documentation › MyBB Security Guide: General Advice →

Infrastructure & Environment

Before recovering your MyBB installation, you should secure access to domains, hosting accounts, reverse proxy, server and additional infrastructure, TLS certificates, as well as other installed applications/scripts.

MyBB Files

To ensure that your MyBB installation is clean and no extra files have been added, delete all hosted files and upload a fresh copy of the latest version of MyBB (after verifying the downloaded package).

Manually rebuild the configuration file, entering database connection details and other necessary values.

MyBB Database

Due to lack of HTML filtering in some portions of the Admin CP and the front-end, malicious code can continue to be executed whenever MyBB is used, and will need to be removed first.

The following actions may be recommended in the table below:

  • Delete & Import

    For tables with content difficult to review manually:

    1. completely delete (DROP) the table,
    2. use structure and default content imported from a new MyBB installation (with the same version as the affected installation).

    Custom content may also need to be reviewed manually and restored after recovery.

  • Clear

    For tables storing temporary or easily replaceable data: delete all content by executing a DELETE SQL command:

    DELETE FROM mybb_example;
  • Review

    For tables storing data that may need to be preserved: use an external tool to list raw values of stored rows and search for suspicious content (usually containing ', ", < characters, intended to break existing HTML tags or insert new ones).

Table Name Content Default Content Recommended Action Alternative Action (if not used/customized)
mybb_adminoptions ACP preferences, notes, permissions (other than Home section) Yes Clear  
mybb_adminsessions ACP login sessions No Clear  
mybb_adminviews ACP View filters for user listing Yes Delete & Import  
mybb_delayedmoderation Delayed Moderation No Clear  
mybb_helpdocs Help Documents Yes Delete & Import  
mybb_helpsections Help Documents sections Yes Delete & Import  
mybb_mailqueue Mass Mail Queue No Clear  
mybb_calendars Calendars Yes Review Delete & Import
mybb_datacache Datacache Yes Delete Redundant entries; Review remaining entries  
mybb_forums List of Forums and Categories Yes Review  
mybb_threadprefixes Thread Prefixes No Review Clear
mybb_usergroups User Groups Yes Review  
mybb_profilefields Custom Profile Fields Yes Review Delete & Import
mybb_mycode Custom MyCode No Review Clear
mybb_settings Settings metadata and values Yes Delete & Import  
mybb_spiders Spiders / Bots Yes Review Clear
mybb_templates Templates Yes Delete & Import  
mybb_templatesets Template Sets Yes Delete & Import  
mybb_themes Themes Yes Delete & Import  
mybb_themestylesheets Theme Stylesheets Yes Delete & Import  
mybb_usertitles User Titles Yes Review Clear

Selective Modifications

Execute the following SQL query to mitigate dangerous values in other tables:

UPDATE mybb_banned SET oldgroup = '2', oldadditionalgroups = '', olddisplaygroup = ''; -- Prevent ban expirations from upgrading users to groups other than "Registered"

MyBB Extensions may use additional tables that will need to be reviewed.

Locally Stored Data

Malicious code served by compromised websites may be saved locally in the browser (e.g. cookies, cache, workers). This can be mitigated by instructing browsers to clear all data.

Copy the following code, replacing RANDOM_VALUE with a random value, and add it to the end of the inc/init.php file:

$clearDataToken = 'RANDOM_VALUE';

if (!isset($mybb->cookies['clear_data_token']) || $mybb->cookies['clear_data_token'] !== $clearDataToken) {
    header('Clear-Site-Data: "cookies", "cache", "storage"');
    header('Refresh: 0');

    my_setcookie('clear_data_token', $clearDataToken);


The code should be active for at least 24 hours (the maximum lifetime of installed service workers) after removing server-side infections.

Forum users with elevated privileges should, in addition, manually clear cookies and other site data stored in their browsers.

Mitigate Impact of Stolen Data

Invalidate Tokens

The database may contain sensitive tokens that can be used on the restored forum, and should be removed — execute the following SQL query:

DELETE FROM mybb_adminsessions; -- Purge ACP login state
DELETE FROM mybb_awaitingactivation WHERE type == 'p'; -- Purge password reset requests
UPDATE mybb_datacache SET cache = 'a:1:{s:14:"encryption_key";s:0:"";}' WHERE title = 'internal_settings'; -- Reset encryption_key used with anti-CSRF tokens
UPDATE mybb_users SET loginkey = ''; -- Purge front-end login state and anti-CSRF tokens

Change API Keys

Secret API keys that may have been compromised should be re-generated (or deactivated and re-created) at their providers (e.g. the Stop Forum Spam API Key) and replaced in MyBB Settings later on. Extensions may maintain additional values that will need to be changed.

Remove Online Database Backups

Database backups previously generated by MyBB that are still stored within the directory structure (by default: admin/backups/) should be moved or deleted, as the disclosure of filenames may make it easier to obtain them by an attacker.

Reset Passwords

User passwords should be reset (regardless of hashing algorithms used) — execute the following SQL query:

UPDATE mybb_users SET password = '';

First login attempts will be rejected by MyBB, forcing users to reset their passwords by e-mail.

Note: no additional columns should be modified for this purpose, as password hashes and salts will be re-generated automatically. Values in the salt column should be preserved to avoid unexpected behavior.

Using MyBB Again

Restore Your Admin Account

Admin Control Panel access can be restored easily by configuring super administrators. If you are having trouble signing in, follow the article on login problems to fix cookie issues or reset your password with an SQL query:

MyBB Documentation › Login Problems →

Perform MyBB Upgrades

If you were running an older version of MyBB, upgrade the board first, as old versions may contain vulnerabilities addressed in more recent releases.

Run Integrity Checks

  • Use the Tools & Maintenance → File Verification tool to verify file integrity. You can also use the DVZ Integrity Tools plugin to verify the structure integrity of MyBB database tables.
  • Validate templates using Tools & Maintenance → System Health → Check Templates.
  • Go to Home → Dashboard → Check for Updates and make sure the board’s version is identical to latest MyBB version.

Review Settings and Forum Behavior

Re-adjust MyBB Settings (Configuration → Settings) that have been reverted to default values in previous steps and review all other options, especially:

  • Moderator Tools (Configuration),
  • forum moderators (Forums & Posts → Forum Management),
  • Admin Permissions (Users & Groups),
  • Moderation/Administration Options and Group Leaders of all User Groups (Users & Groups → Groups),
  • Group Promotions (Users & Groups).

Review MyBB Logs

In addition to access logs generated by the server, you should review MyBB’s own logs that may contain information related to the security breach and actions executed automatically after the forum was restored:

  • Tools & Maintenance → Logs,
  • Users & Groups → Mass Mail → Mass Mailing Archive,
  • Users & Groups → Group Promotions → View Promotion Logs,
  • Tools & Maintenance → Task Manager → View Task Logs.

Review & Restore Customizations

If you have customized your board using plugins, themes, images, language packs and other custom modifications, you can use one of the previous backups to review and restore them (note it is possible that a vulnerability lies within such customizations).

MyBB Documentation › Directory Structure →

General Security Measures

Continue with the general MyBB Security Guide to finish securing your board: existing measures may have not been implemented correctly, or may have been compromised.

MyBB Documentation › Security Guide →


Affected Users

It is considered industry practice (and may be required by law) to make affected users aware of a potential data breach, usually by e-mail. This notification should be easy to understand for non-technical users and include:

  • a description of what happened and when,
  • what information was, or may have been, affected,
  • potential consequences for people whose data was involved,
  • what measures you have taken, are taking, or will take to mitigate the problem,
  • steps people should take to reduce potential impact of the event (like changing passwords on your forums and any other websites/applications where the password was re-used),
  • contact details.

It is also a good idea to add an easily discoverable announcement thread with same details.

Local Authorities

Depending on the country of operation, supervisory authorities may need to be notified about data breaches. Additionally, administrators may be required, or choose, to report malicious activity to law enforcement organizations.

Selected data breach regulations:

Hosting Company

We recommend contacting your hosting company if you have difficulty identifying attackers’ entry points (especially if using shared hosting). There is a possibility that the attackers used host servers outside of your control first, or found a way to access it through your web account. The web host may also be able to provide additional information like logs and backups that may help with the recovery process.

MyBB Team

You can contact the MyBB Team to share details related to the incident, especially if you suspect the breach to be related to vulnerabilities in MyBB or extensions. This information will also help track exploitation attempts of active MyBB boards.

See also:

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