The importance of blacklists in cybersecurity

Blacklists are a fundamental tool in cybersecurity that allows you to block digital elements classified as suspicious or malicious to protect systems.

What is a cybersecurity blacklist?

One of the most widespread and effective tools in the fight against cyber threats is blacklists. But what exactly are they, and how do they work?

A cybersecurity blacklist is a database that contains IP addresses, domains, emails, applications, or any other digital item that has been identified as malicious or suspicious. Security systems automatically block these elements to prevent cyberattacks.

Blacklists are used by a variety of security solutions, including firewalls, intrusion detection and prevention systems (IDS/IPS), and antivirus software. When a blacklisted item attempts to access a system, the request is automatically rejected.

Public blacklists are maintained by cybersecurity organizations, Internet Service Providers (ISPs), and security software companies. These lists are constantly updated to reflect new threats as they are discovered.

In turn, organizations can create private blacklists to protect their systems from specific threats.

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Types of Blacklists

There can be as many types of blacklists as there are categories of threats that have been detected. The most common are:

IP Blacklist

The IP blacklist contains a series of IP addresses identified as potentially dangerous. These IP addresses are often associated with malicious activities, such as spamming, DDoS attacks, malware propagation, etc.

IP blacklists are used to block traffic coming from these IP addresses automatically. When an IP address appears on a blacklist, any attempt to connect from that IP address to a protected system is rejected.

IP blacklists are maintained and updated by cybersecurity organizations and Internet service providers. They are constantly updated to reflect new threats as they are discovered or exclude those that have disappeared.

Although IP blacklists are a valuable tool in preventing cyber threats, they are not foolproof. To avoid blocking, cybercriminals change IP addresses regularly.

Blacklist of spam domains

A spam domain blacklist contains a list of domain names that have been identified as sources of junk mail or spam. These domains can be associated with distributing unsolicited emails, phishing, malware, and other malicious activities.

Email security systems and spam filters use spam domain blacklists to block emails coming from these domains automatically. When a domain appears on a blacklist, any email sent from that domain to a protected system is marked as spam or rejected.

Like the rest of the public blacklists, spam domain blacklists are maintained and updated by cybersecurity organizations, email service providers, and security software companies. They are also constantly updated, as cybercriminals frequently change domain names to get around them.

How Blacklists Work

Blacklists are built through the collection and comprehensive analysis of data on known threats.

The process for creating a blacklist includes:

• Data collection. Data is collected from multiple sources, such as security incident reports, threat intelligence feeds, and internal analytics.
• Data analysis. The collected data is analyzed to identify malicious patterns and behaviors. It includes analyzing IP addresses, domains, emails, and applications associated with malicious activities such as spam or cyberattacks.
• Blacklist creation. Once the malicious items are identified, they are added to the blacklist.
• Constant updating. Blacklists should be constantly updated to reflect new threats as they are discovered and fix bugs detected.

Once the blacklist is drawn up, it is used to automatically block access to the organization’s systems by the digital elements collected in it.

Main benefits of blacklists

Using blacklists for the protection of systems is a solution that brings numerous benefits, among which the following stand out:

Easy Deployment

Implementing blacklists is relatively straightforward, making them an attractive option for many organizations. These lists can be easily configured in most security systems, such as firewalls and intrusion detection systems.

The ease of deployment allows organizations to quickly improve their security posture without requiring significant resources.

Proactive Protection

Blacklists offer proactive security protection by identifying and blocking known threats before they can cause harm. These lists act as a shield by restricting access to suspicious entities and preventing threat actors from exploiting vulnerabilities.

This proactive approach allows organizations to anticipate threats and prevent them from materializing rather than simply reacting to them once they have occurred.

Complement to security strategies

Blacklists are a valuable complement to other security strategies. They are effective at blocking known threats, but they cannot protect against unknown or zero-day threats.

Therefore, they are helpful with different techniques, such as anomaly detection and threat intelligence. Together, these strategies provide defense-in-depth protection against a broader range of threats.

Reduction of malicious traffic

Blacklists are very effective in reducing malicious traffic. By blocking IP addresses, domains, and emails associated with malicious activity, blacklists significantly decrease the amount of unwanted or harmful traffic.

This improves security and increases network efficiency by reducing unnecessary traffic.

Blacklist limitations

Blacklists are a simple and effective tool to protect systems; however, they have limitations that force them to be integrated within a set of tools.

The main limitations of blacklists are:

False positives

Blacklists often include erroneous collections or scans that lead to the blocking of legitimate traffic, an incidence known as false positives. These false positives harm the organization, blocking legitimate traffic and the organization from which that traffic originates.

To address false positives, many organizations use a combination of blacklists and whitelists. Whitelists, unlike blacklists, contain items that are considered safe and allowed. Combining the two list types allows for more granular control and reduces the chance of false positives.

Need for constant updating

To get around blacklist blocking, cybercriminals repeatedly change IP addresses, domains, or anything else that may be on a blacklist. Therefore, to maintain their effectiveness, blacklists require a constant update of their database that reflects new threats as they are discovered, which is a significant cost in resources.

Blacklist implementation through Kartos by Enthec

Kartos XTI Watchbots, the Cyber Intelligence platform developed by Enthec, makes it easy for its customers to create private blacklists based on Kartos’ findings and the results of their analyses carried out through our in-house developed artificial intelligence solutions.

In this way, in addition to the protection of general blacklists, our clients add that of private blacklists that respond to the specific context of the organization.

Contact us to learn about the benefits of incorporating our Kartos by Enthec Cyber Intelligence solution into your organization’s Cybersecurity strategy to detect exposed vulnerabilities, open gaps, create blacklists and eliminate false positives.