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How to protect from an RDP Brute Force attack

We should not make it simple for thieves by leaving our ports and servers exposed. This is one of the main reasons for RDP brute force attacks. Read along to learn more!

19 Oct, 21 by Susith Nonis 6 min Read

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The global workforce is growing more dispersed. The advent of remote working, outsourcing, and cloud-based technology continues to reduce geographical barriers, allowing small and medium-sized businesses to access a large and varied labour pool.

To sustain the systems that allow this type of working arrangement, many small and medium-sized businesses (SMEs) depend on off-site technical support services that use remote desktop protocol (RDP) to detect and resolve network problems. RDP is a network protocol that allows a terminal server and a terminal server client to interact securely. Network administrators frequently use it to get remote access to virtual desktops and apps.

Though Remote Desktop Protocol can be a security concern in and of itself, businesses frequently compound the risks by neglecting to adequately protect RDP accounts and services. Accounts having RDP access may have a weak password or no extra security measures.

These vulnerabilities allow attackers to utilise automated methods to acquire the account password through brute force assaults. If the attackers are successful, they may then infiltrate a network, get administrator access, disable security products, and even execute ransomware to encrypt vital data and hold it hostage.

Using RDP does entail some danger, especially as unprotected remote desktops are quickly becoming a favourite method of access for hackers. Unfortunately, many businesses are leaving themselves vulnerable by failing to implement a few easy security precautions.

In this post, we'll explain how RDP brute force assaults operate and what you can do to keep your system safe from this sort of intrusion. 

A brute force attack occurs when an attacker attempts every possible method to gain access. Including hurling everything in the kitchen at it. While attempting to get access to your system, they would try an infinite number of login credentials until one of them succeeds.

Brute force assaults are often automated, so the attacker does not have to use a lot of time or energy. Definitely not as much as figuring out how to connect to a remote system through your own. The attacker chooses the victim and technique based on a port number or another framework feature before launching his brute force software.

He can then proceed to the next target and be alerted when one of the systems swallows the hook.

An attacker will use one of the following approaches while attempting to gain access to a remote system:

1.   Reverse Brute force Attack

This kind employs a single password or a set of passwords against a large number of potential usernames. The attacker could know the identity credentials or at least a piece of it. For example, they may be aware that a certain organization's workers' default username is the firstname.surname@organization. The attacker can then attempt a predefined set of users and random passwords.

2.   Hybrid Brute force Attack

A hybrid brute force approach begins with the most likely combinations and then continues to attempt from there. It frequently employs a dictionary attack, in which the program attempts usernames and passwords against a dictionary of potential letters or phrases.

3.   Credential stuffing

Credential stuffing is a form of attack in which the criminal possesses a database of legitimate login and password combinations (often acquired from prior breaches) and attempts all of these combinations on various systems. This is why reusing passwords is never a smart idea.

4.   Rainbow table Attack

Rainbow table attacks are only effective when the attacker knows anything about the credentials they are attempting to guess. Rainbow tables are employed in these attacks to retrieve a password depending on its hash value. A rainbow table is a hash algorithm used in cryptography to store critical data in a database, such as passwords.

  1. Improve password length: Longer passwords are more difficult to crack using brute force.
  2. Improve password Complexity: Password complexity may be increased by avoiding patterns, popular phrases, and dictionary terms in passwords. This can help make them more resistant to password assaults.
  3. Restrict login Attempts: Set a barrier for the number of unsuccessful logins attempts to prevent the brute-force tool from trying too many combinations of usernames and passwords. When this value is reached, the machine should be locked.
  4. Use of CAPTCHA: CAPTCHA may be used to prevent automated bots from attempting to log in. This renders brute-force assaults unsuccessful since it is physically impossible to test all conceivable username-password combinations in order to locate the correct pair. Even if they attempted, it would take an eternity.
  5. Use of Multi-factor authentication(MFA): Set up multi-factor authentication: No matter how secure your password is, it is still vulnerable to phishing attempts. As a result, other authentication elements, such as biometrics, should be used to secure logins.
  6. Virtual private network

A VPN is a typical method of restricting RDP port access. Organizations may add an extra layer of verification to keep the bad guys out by setting up a VPN.

VPNs, of course, offer their own set of potential disadvantages. Setting up a VPN might be too complex for some businesses' already overburdened IT departments. Furthermore, while a VPN will assist to protect a VM, if it is secured with a weak, repeated password, it, too, maybe brute-forced by bot assaults.

6- Setup Remote Desktop Gateway

When an RDP Gateway is deployed, any Distant Desktop port access from a remote connection is handled by a single Gateway server. You should ensure that any Remote Desktop systems running on computers and servers only offer access from the designated Remote Desktop Gateway if you choose this alternative.

The Remote Gateway server connects users to Remote Desktop Services on the target computers by accepting Remote Desktop requests via a secure HTTPS protocol (Port 443). You may also limit the resources that users are allowed to utilize using Remote Desktop Gateway.

We should not make it simple for thieves by leaving our ports and servers exposed. These security guidelines should assist you in strengthening the security landscapes of your server and Remote Desktop Protocol.

Susith Nonis

I'm fascinated by the IT world and how the 1's and 0's work. While I veture into the world of Technology I try to share what I know in the simplest way possible. Not a fan of coffee, a sweet addict and a self accredited 'master chef'.