Brute force username question

[jonh]

Hello, I have a new server created in the last few days and it has cphulk on and working. I received an email from cphulk, basically it was cphulk blocking a brute force attempt against FTP using one of the account usernames. The username is not standard, it's a not something they could guess.

I'm wondering how they would even know this username exists?

(Channel already responded to my ticket saying audit the logs, but wondering if community has any other info.)

 

[cPanelMichael]

I'm wondering how they would even know this username exists?

Hello

It's difficult to say exactly how the guess on the username occurred. Is it possible the username was utilized by a user with a hacked workstation? Or, do you notice any other entries in /var/log/messages where the attempt to guess the FTP username materialized?

Thank you.

 

[jonh]

"Is it possible the username was utilized by a user with a hacked workstation?"
Since the server was built I've used FTP 2 times, on two different accounts. The cphulk FTP notifications have been coming steady since the server was turned on. Most of the notifications are for easily guessed names. Nothing has materialized. Anyway to turn off FTP and use Ssh/SFTP?

 

[cPanelMichael]

Anyway to turn off FTP and use Ssh/SFTP?

You can disable FTP via:

"WHM >> FTP Server Selection"

However, note there is no replacement in the cPanel interface to create virtual SFTP accounts.

Thank you

 

[jonh]

I'm getting like 100 Brute Force attempt against pure-ftp each day. Do I worry about this, just turn off the notifications or shut down pure-ftp when not in use?

 

[cPanelMichael]

New I'm getting like 100 Brute Force attempt against pure-ftp each day. Do I worry about this, just turn off the notifications or shut down pure-ftp when not in use?

Have you installed a firewall management application such as CSF to help block these types of brute force attacks?

Thank you.

 

[jonh]

YES, it's sending me the notifications.

 

[cPanelMichael]

If the attack is coming from different IP addresses each time, then you may want to disable FTP and require users to utilize SFTP with the cPanel account username. Or, you could switch to ProFTPD and utilize the host access control option to restrict FTP access to specific IP addresses:

Host Access Control - Documentation - cPanel Documentation

Thank you.

 

[jonh]

Thank you for both solutions! Do you have any additional info on how to do this part: "disable FTP and require users to utilize SFTP"?

 

[cPanelMichael]

The suggestion was based on your earlier question:

Anyway to turn off FTP and use Ssh/SFTP?

You can disable FTP via:

"WHM Home » Service Configuration » FTP Server Selection"

However, note that users will not be able to create virtual FTP accounts via cPanel. Instead, they will need to use a FTP client that supports SFTP and access it via their cPanel username:

How to Configure Your SFTP Client - cPanel Knowledge Base - cPanel Documentation

Thank you.

 

[keat63]

jonh.

first thing i would do would be to install CSF, it's a free firewall, and provided you choose the correct options will work straight out of the box.

Additional things like utilising Host Access Control.
You add a list of IP's that you trust to use SSH, FTP and a few other services, and an entry right at the end that says deny all services to all users.
If you're allocated dynamic IP's then you might have to allow a few subnets, eg 123.456.0.0/16 and 123.678.0.0/16, but this would essentially kill any attempt to ftp in, unless you're in the whitelist.
You would need to ensure that you have a few ways to get in yourself though. Work, Home, Parents etc, and also maybe your Host Provider.