How to Prevent and Stop Hacking in Microsoft SQL Server

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How to Identify and Stop SQL Server Hacking Attempts

Microsoft SQL Server (MS SQL Server) is a robust and widely used relational database management system. However, as with any system that handles critical data, it is a target for hacking attempts. This blog will guide you through identifying suspicious activities, stopping ongoing attacks, and implementing security measures to prevent future breaches. Whether you are a database administrator or IT professional, these steps will help you safeguard your MS SQL Server.

Step 1: Identify Suspicious Activity

The first step in addressing a potential hacking attempt is detecting unauthorized or unusual activities in your SQL Server.

Check Active Sessions

Use the following query to monitor all active connections:

SELECT
    session_id,
    host_name,
    login_name,
    status,
    program_name,
    login_time
FROM sys.dm_exec_sessions;

Look for suspicious patterns, such as unknown hostnames or programs accessing the server.

Identify Running Queries

Inspect ongoing queries to detect malicious activity:

SELECT
    r.session_id,
    r.status,
    r.start_time,
    s.host_name,
    s.program_name,
    s.login_name,
    q.text AS query_text
FROM sys.dm_exec_requests r
JOIN sys.dm_exec_sessions s ON r.session_id = s.session_id
CROSS APPLY sys.dm_exec_sql_text(r.sql_handle) q;

Focus on:

  • Queries from unknown users or programs.
  • Unusually long-running or resource-intensive queries.

Review SQL Server Logs

SQL Server logs are an essential source of information for identifying suspicious activities. Use SQL Server Management Studio (SSMS) or the following query to access the error logs:

EXEC sp_readerrorlog;

Look for:

  • Failed login attempts.
  • Errors indicating unauthorized access attempts.

Step 2: Stop Malicious Activity

Once you’ve identified suspicious activity, take immediate action to stop it.

Kill Suspicious Sessions

Terminate any session you suspect of unauthorized activity:

KILL <session_id>;

Replace <session_id> with the ID from the sys.dm_exec_sessions query.

Disable Compromised Accounts

If a user account has been compromised, disable it to prevent further access:

ALTER LOGIN [<username>] DISABLE;

You can also lock out the account temporarily by setting a login attempt limit using SQL Server security policies.

Step 3: Block Further Access

Restrict IP Addresses

Use a firewall to block unauthorized IP addresses or restrict access to trusted IPs only:

EXEC xp_cmdshell 'netsh advfirewall firewall add rule name="BlockSuspiciousIP" dir=in action=block remoteip=<suspicious_ip>';

Alternatively, configure the database server’s security group if hosted on a cloud platform like Azure.

Audit and Remove Excessive Permissions

Ensure all accounts have the least privilege necessary. Check permissions with:

SELECT
    dp.name AS username,
    dp.type_desc AS type,
    p.permission_name,
    p.state_desc AS state
FROM sys.database_permissions p
JOIN sys.database_principals dp ON p.grantee_principal_id = dp.principal_id;

Revoke unnecessary permissions:

REVOKE <permission> ON <object> FROM <username>;

Step 4: Implement Advanced Security Measures

Use Strong Password Policies

Enforce strong passwords for all users by enabling password policies in SQL Server:

ALTER LOGIN [<username>] WITH CHECK_POLICY = ON;

Enable Encryption

Encrypt connections between clients and the server to protect data in transit. Use SSL certificates for this purpose. Configure encryption in SQL Server Configuration Manager by enabling the “Force Encryption” option.

Monitor and Log All Activities

Enable SQL Server Audit to log and monitor all database activities. Use the following steps:

Step 1: Create an audit object:

    CREATE SERVER AUDIT [AuditName]
TO FILE ( FILEPATH = 'C:\AuditLogs\' );
ALTER SERVER AUDIT [AuditName] WITH (STATE = ON);

    Step 2: Create an audit specification:

    CREATE SERVER AUDIT SPECIFICATION [AuditSpecName]
FOR SERVER AUDIT [AuditName]
ADD (SUCCESSFUL_LOGIN_GROUP, FAILED_LOGIN_GROUP);
ALTER SERVER AUDIT SPECIFICATION [AuditSpecName] WITH (STATE = ON);

    This logs all successful and failed login attempts.

    Step 5: Monitor and Audit Regularly

    Use Extended Events

    Set up Extended Events to track specific activities or performance issues:

    CREATE EVENT SESSION [TrackSuspiciousActivity] ON SERVER
ADD EVENT sqlserver.error_reported
(WHERE severity >= 20)
ADD EVENT sqlserver.login
ADD TARGET package0.event_file (SET filename = 'C:\Logs\SuspiciousActivity.xel');
ALTER EVENT SESSION [TrackSuspiciousActivity] ON SERVER STATE = START;

    Review Database Roles

    Audit roles assigned to users to ensure no excessive privileges are granted:

    SELECT
    r.name AS role_name,
    m.name AS member_name
FROM sys.database_role_members drm
JOIN sys.database_principals r ON drm.role_principal_id = r.principal_id
JOIN sys.database_principals m ON drm.member_principal_id = m.principal_id;

    Step 6: Long-Term Security Strategies

    Regularly Patch SQL Server

    Keep your SQL Server instance updated with the latest security patches from Microsoft. Use Windows Update or download updates directly from Microsoft’s website.

    Backup Your Data

    Regularly back up your database to recover from potential breaches or data corruption:

    BACKUP DATABASE [YourDatabase] TO DISK = 'C:\Backups\YourDatabase.bak';

    Automate backups using SQL Server Agent.

    Use Monitoring Tools

    Employ third-party monitoring tools like SolarWinds, Redgate, or Microsoft’s Azure Monitor to detect anomalies and performance issues in real time.

    Conclusion

    Securing your SQL Server is an ongoing process. By detecting and stopping malicious activities promptly and implementing strong security measures, you can safeguard your database from hackers. Regular audits, monitoring, and updates are essential to maintaining a secure environment.

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