by | Apr 2, 2024 | Threat Lab

Reading Time: ~ 3 min.

Brute force attacks illustrate how persistence can pay off. Unfortunately, in this context, it’s for bad actors. Let’s dive into the mechanics of brute force attacks, unraveling their methodology, and focusing on their application. Whether it’s Remote Desktop Protocol (RDP), or direct finance theft, brute force attacks are a prime tactic in the current cybersecurity landscape.

What is a Brute Force Attack?

A brute force attack is a cyber attack where the attacker attempts to gain unauthorized access to a system or data by systematically trying every possible combination of passwords or keys. This method relies on the sheer power of repetition and the computational capacity to try thousands, if not millions, of combinations in a short time span. Think of it as trying every key on a keyring until finding the one that unlocks a door.

Types of Brute Force Attacks

• Simple brute force attacks: This basic approach involves trying all possible combinations of characters until the correct one is found.
• Dictionary attacks: A more refined method that uses a list of pre-existing passwords, phrases, or commonly used combinations instead of random permutations. There are many already leaked password lists that are commonly used, and they grow after every breach.
• Hybrid attacks: Combining elements of both the simple and dictionary approaches, often tweaking common passwords slightly to guess more complex passwords.

The Role of GPUs in Brute Force Attacks

Graphic Processing Units (GPUs) have revolutionized not just gaming and graphic design, but also the world of cybersecurity. Their powerful parallel processing capabilities make them particularly adept at handling the computational demands of brute force attacks. Unlike Central Processing Units (CPUs) that process tasks sequentially, GPUs can perform thousands of operations simultaneously, drastically reducing the time required to crack passwords or encryption keys.

Accelerating Brute Force Techniques

Cybercriminals exploit GPUs to accelerate the brute force process, enabling them to try billions of password combinations in seconds. This brute force capability poses a significant threat to systems protected by weak or commonly used passwords. It underscores the necessity for robust password policies and advanced security measures like Multi-Factor Authentication (MFA) and encryption methods resilient against GPU-powered attacks.

Financial Applications of Brute Force Attacks

The financial implications of brute force attacks can be profound, ranging from direct financial theft to substantial reputational damage leading to loss of business.

Direct Financial Theft

In some cases, attackers aim to gain unauthorized access to financial systems or payment platforms. By cracking login credentials through brute force, they can transfer funds, manipulate transactions, or steal sensitive financial information, leading to direct monetary losses.

The Role of RDP in Brute Force Attacks

Remote Desktop Protocol (RDP) is a proprietary protocol developed by Microsoft that allows a user to connect to another computer over a network connection with a graphical interface. While RDP is a powerful tool for remote administration and support, it has also become a favored vector for brute force attacks for several reasons:

• Widespread use: RDP is commonly used in businesses to enable remote work and system administration.
• Open ports: RDP typically requires port 3389 to be open, making it a visible entry point for attackers scanning for vulnerabilities.
• Direct access: Successfully breaching an RDP session can give attackers direct control over a victim’s computer, allowing for the deployment of malware, ransomware, or theft of sensitive information.

Real-World Examples of Brute Force Attacks via RDP

1. Ransomware Deployment: One of the most nefarious uses of brute force attacks on RDP is for the deployment of ransomware. Once access is gained, attackers can encrypt the victim’s files, demanding a ransom for their release. The WannaCry and Ryuk ransomware attacks are notable examples where such tactics were likely utilized.
2. Credential Stuffing: In some cases, attackers use brute force tactics to validate stolen username and password combinations against accessible RDP servers. This method relies on the assumption that many users reuse their credentials across different services.
3. Network Infiltration: Upon gaining access via RDP, cybercriminals can use the compromised system as a foothold to explore and exploit further vulnerabilities within a network, aiming for more valuable data or systems.

Mitigating the Risk

Protecting against brute force attacks, especially on RDP, involves a multi-faceted approach:

• Strong Password Policies: Enforce complex, unique passwords and consider the use of multi-factor authentication (MFA) to add an extra layer of security.
• Account Lockout Policies: Implement policies that lock user accounts after a certain number of failed login attempts to hinder brute force efforts.
• Network Level Authentication (NLA): NLA requires users to authenticate before establishing an RDP session, significantly reducing the risk of brute force attacks.
• VPN Usage: Restrict RDP access to users connected through a Virtual Private Network (VPN), reducing the exposure of RDP to the open internet.
• Monitoring and Alerts: Use security tools to monitor for repeated failed login attempts and configure alerts to notify administrators of potential brute force activities.