Protect Microsoft SQL Server from Brute-Force Attacks and Repeated Failed Logins
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Intrusion prevention system for your Windows Server
 

How to Stop Brute-Force Attacks on MS-SQL Server

If you are running Microsoft SQL Server, you are probably aware of brute-force attacks on the SA account. An Internet-facing SQL server can face a constant stream of automated login attempts.

A compromised SQL login can expose or destroy data. An SA account gives an attacker full control of SQL Server, and the Windows permissions granted to the SQL Server service may also allow access to local or network files.

If your SQL server accepts remote connections, its logs may contain thousands of failed login attempts. This SQL Server error log excerpt shows five attempts in less than a second:

Date and time             Error      Login       Client IP
2020-02-03 09:45:29.31    18456      sa          61.12.74.190
2020-02-03 09:45:29.42    18456      mssqla      112.53.236.114
2020-02-03 09:45:29.48    18456      sa          61.12.74.190
2020-02-03 09:45:29.73    18456      sa          61.12.74.190
2020-02-03 09:45:30.08    18456      sa          61.12.74.190
Selected SQL Server error log entries: repeated failed logins.

The Windows Application log can also record failed SQL logins as Event ID 18456. Here is an example of a failed SA login:

Log Name:  Application
Source:    MSSQL$SQLEXPRESS
Event ID:  18456

Description:
Login failed for user 'sa'.
Reason: Password did not match that for the login provided.
[CLIENT: 58.221.64.70]
SQL Server event 18456: failed SA login with the client's IP address.

Repeated failed logins from an unfamiliar IP can mean that someone is trying to get access to your server. Brute-force attacks can also abuse your server resources, including CPU, RAM, and bandwidth.

RdpGuard allows you to protect your MS SQL Server from brute-force attacks.

It monitors the Windows Application log and detects failed login attempts. If the number of failed login attempts from a single IP address reaches a set limit (three by default), the attacker's IP address will be blocked!

For 64-bit Windows and Windows Server. Supported Windows versions.

See Also

How to Enable and Configure MS-SQL Brute-Force Protection

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