How can I protect myself from Bad Bot (Spambot, Attacker )?

Agent

A human will use generally use a real browser (as agent) to interact with the website and sign up.

A bot is not a browser and may not implement:

• cookie
• javascript execution

You may implement rule such as:

• Do something afterwards if the cookie is present.
• Show my forms via Javascript

Example:

• The external form html in the server

<form action="" method="post">
<input type="email" value="" name="EMAIL" class="email" placeholder="email address">
<input type="submit" value="Subscribe" name="subscribe" class="button">
</form>

• The HTML page (that does not have any form - only a anchor newsletter_form to point where the form should be added)

<h2>My Form</h2>
<div id="newsletter_form"></div>

• This Web Api Fetch will add the form

// Web Api
let pagePath= parent.JSINFO.id.replace(":","/");
fetch(`/_export/code/${pagePath}?codeblock=1`, {
    method: 'GET', // *GET, PUT, DELETE, etc.
  })
  .then(function(response) {
    // Response text is a promise, you need to pass it to a callback to resolve it
    response.text().then(function(data) {
       document.getElementById('newsletter_form').innerHTML=data;
    });
})

// or Jquery
// For Jquery, you can also use [[https://api.jquery.com/load/|Jquery load]]
// $('#newsletter_form').load('/_export/code/email/fake?codeblock=0');

• Result:

Browser

A human will use generally the same browser to sign up and confirm the email.

By setting a cookie or taking the browser fingerprint, we can see if the signup and the confirmation was done with the same browser.

Browser fingerprinting is also used to identify the characteristics of botnets, because the connections of botnets are established by a different device every time. See device-tracking-by-web-sites-can-be-a-good-thing/

A bot (hacker) who logged into the account using a device that had never accessed the account before can potentially be identified.

Computer / IP

A human will

• use generally the same computer to sign up and confirm the email.
• not signup multiple time from the same computer
• not submit form more than once in a 24 hour period (Shopify shows a captcha challenge if this is the case)

By taking the browser fingerprint (and IP), we can monitor this behavior.

High Engagement

Because a bot will click on all links, it will ends up with a high engagement score that no human could achieve.

• open rate of 100% (open email by mail send)
• click through rate of 100%
• and so on

A high engagement score within a short period of time is a big red flag.

Firewall

You can restrict access by Ip Address or Mac Address.

You can therefore also restrict access by country. Example: How to restrict your traffic to a country with Firewalld / Iptable? (ie packet filtering by country)

Black list

From bad behavior, there are blacklist created where the IP or domain are registered.

When receiving a connection, you can check these lists and taking action accordinlgly.

Tarpit

A tarpit is a network service that intentionally inserts delays in the protocol banner, slowing down clients by forcing them to wait. The cost is a socket but no high CPU or memory usage.

Example:

• Ssh tarpit: Endlessh: an SSH Tarpit. (skeeto/endlessh)

Port knocking

Port knocking redirects your traffic to a port with a routing command (for instance iptables) only if it receives a good sequence.

Example with knockd to manage an SSH port.

/etc/knockd.conf

[options]
        UseSyslog

[openSSH]
        sequence    = 7000,8000,9000
        seq_timeout = 5
        command     = /sbin/iptables -A INPUT -s %IP% -p tcp --dport 22 -j ACCEPT
        tcpflags    = syn

[closeSSH]
        sequence    = 9000,8000,7000
        seq_timeout = 5
        command     = /sbin/iptables -D INPUT -s %IP% -p tcp --dport 22 -j ACCEPT
        tcpflags    = syn