What is SSH Brute Force Attack And How To Deal With It (2024)

LAST UPDATED: MAY 09, 2023

What is SSH?

SSH or Secure Shell is a popular cryptographic network protocol used for secure remote login and file transfer. However, with the rise of cybercrime, SSH has become a target for malicious actors who attempt to gain unauthorized access to remote servers by guessing login credentials. This is known as an SSH brute force attack, and it can have devastating consequences if successful.

What is an SSH Brute Force Attack?

An SSH brute force attack is a hacking technique that involves repeatedly trying different username and password combinations until the attacker gains access to the remote server. The attacker uses automated tools that can try thousands of username and password combinations in a matter of seconds, making it a fast and effective way to compromise a server.

How It Works

An SSH brute force attack exploits weak or default passwords that are commonly used on servers. These passwords can be easily guessed by attackers using common passwords lists and automated tools. Once the attacker gains access, they can then use the server for malicious purposes, such as stealing data or launching further attacks.

How to Prevent SSH Brute Force Attacks

Preventing SSH brute force attacks requires a multi-layered approach that involves both technical and administrative controls. Here are some steps you can take to prevent SSH brute force attacks:

  • Use Strong Passwords: Always use strong passwords that are difficult to guess. Passwords should be at least 12 characters long and contain a mix of upper and lower case letters, numbers, and special characters.

    You can use our Password Generator to create strong passwords here: https://pwm.trendmicro.com/password-generator

  • Limit Login Attempts: Configure your SSH server to limit the number of
  • Use SSH Keys: Consider using SSH keys instead of passwords. SSH keys are a pair of cryptographic keys that can be used to authenticate users

    This is a more secure authentication method than passwords because the private key is never transmitted over the network.

  • Use a Firewall: Use a firewall to restrict access to your SSH server. Only allow connections from trusted IP addresses or ranges.
  • Monitor Logins: Monitor your SSH logs for unusual activity. This will help you detect any unauthorized login attempts and take action to prevent further attacks.

How Trend Micro can help with SSH Brute Force Attack

While Trend Micro Home Products do not have a direct solution for SSH Brute Force Attack, they can help in mitigating the risk of such attacks by providing endpoint protection for home users. Their products offer advanced protection against online threats such as malware, phishing, and web threats through features like anti-malware, anti-phishing, and web threat protection. Additionally, Trend Micro Home Network Security can provide protection for home networks, including network intrusion detection and prevention.

See also

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What is SSH Brute Force Attack And How To Deal With It (2024)

FAQs

What is the simplest way to stop brute-force cyberattacks? ›

Use stronger password practices

The best way to defend against brute force attacks that target passwords is to make passwords as tough as possible to crack. End-users have a key role to play in protecting their and their organization's data by using stronger passwords and following strict password best practices.

What is SSH brute force attack? ›

An SSH brute force attack is a hacking technique that involves repeatedly trying different username and password combinations until the attacker gains access to the remote server.

Can SSH keys be brute forced? ›

Benefits of SSH Key Authentication

SSH is also resistant to brute force attacks and protects against certain attack vectors used to gain access to remote machines.

What is the best defense against a brute-force login attack? ›

How to prevent brute force attacks
  • 1 - Use Strong Passwords. Brute force relies on weak passwords. ...
  • 2 - Restrict Access to Authentication URLs. A requirement for brute force attacks is to send credentials. ...
  • 3 - Limit Login Attempts. ...
  • 4 - Use CAPTCHAs. ...
  • 5 - Use Two-Factor Authentication (2FA) ...
  • 6 - Set Up IP Access Restrictions.

What can be used to mitigate against brute-force SSH attacks? ›

Limit the number of authentication attempts

One of the simplest ways to mitigate brute force attacks is to reduce the number of authentication attempts permitted by a connection. We can do this by reducing the value of the MaxTries variable in the sshd_config file from its default of 6.

What would block brute force attacks? ›

The most obvious way to block brute-force attacks is to simply lock out accounts after a defined number of incorrect password attempts. Account lockouts can last a specific duration, such as one hour, or the accounts could remain locked until manually unlocked by an administrator.

Which tool is best for SSH brute force? ›

Ncrack is also a popular password-cracking tool for cracking network authentications. It supports various protocols including RDP, SSH, HTTP(S), SMB, POP3(S), VNC, FTP and Telnet. It can perform different attacks including brute-forcing attacks. It supports various platforms including Linux, BSD, Windows and Mac OS X.

What attacks is SSH vulnerable to? ›

The vulnerability is known as Terrapin, the CVE-2023-48795, which is a prefix truncation attack. The Terrapin vulnerability allows attackers to extract messages from servers and clients by making changes to sequence numbers during handshake processes to establish secure communication channels.

What is brute force attack in simple words? ›

A brute force attack uses trial-and-error to guess login info, encryption keys, or find a hidden web page. Hackers work through all possible combinations hoping to guess correctly.

How SSH can be exploited? ›

SSH session hijacking and unauthorized access: Attackers can hijack a user's SSH session by exploiting the trusted communication established between multiple systems via public key authentication in an SSH session. It can occur either by hijacking the SSH agent or by gaining unauthorized access to the agent's socket.

How do I protect my SSH key? ›

To add an extra layer of security, you can add a passphrase to your SSH key. To avoid entering the passphrase every time you connect, you can securely save your passphrase in the SSH agent.

How often should SSH keys be changed? ›

It is recommended that all keys be rotated as part of a remediation process to ensure that any previously leaked keys cease to be usable.” Trend Micro, on the other hand, is more specific. They say that you should rotate SSH public keys approximately every month-and-a-half (i.e., every 45 days).

How long does a brute force attack last? ›

How Long It Takes to Crack a Password with Brute Force Algorithm
8 characters password12 characters password
Lowercase letters onlyinstantlyseveral weeks
+ 1 uppercase letterhalf an hour5 years
+ 1 numberone hour2 thousand years
+ 1 special symbolone day63 thousand years

What is the weakness of brute force attack? ›

A delay of even a few seconds can greatly weaken the effectiveness of a brute force attack. Users of web services can decrease their vulnerability to brute force attacks by choosing longer, more complex passwords. It is also recommended to enable two-factor authentication and use unique passwords for each service.

What is the success rate of brute force attacks? ›

How successful are brute force attacks? Theoretically, brute force attacks have a 100% success rate, though the hacker may have to wait years for their automated systems to correctly guess a complex password.

Which form of encryption offers the best protection against brute force attacks? ›

To bolster encryption against brute force attacks, opt for secure, widely accepted algorithms like AES, RSA, or ECC, known for their complexity and large key sizes, making decryption via brute force extremely challenging. Ensure to use adequate key lengths; for instance, AES with a 256-bit key offers robust protection.

Which security mechanism is designed to protect against offline brute force attacks? ›

Stronger brute-force attack protection.

WPA3 protects against offline password guesses by giving users only one guess attempt, making them interact with a Wi-Fi device directly. This means the user must be physically present every time they want to guess the password.

Do firewalls protect against brute force attacks? ›

Security tools, including a Web Application Firewall (WAF), a Security Configuration Manager, and other monitoring tools and filters can limit the impact of brute force attacks.

How can rate limiting techniques stop brute force attacks? ›

Rate limiting is often employed to stop bad bots from negatively impacting a website or application. Bot attacks that rate limiting can help mitigate include: Brute force attacks. DoS and DDoS attacks.

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