Did you know that every device connected to the internet has a unique identifying label? This label, which is called an Internet Protocol (IP) address, helps firewalls and other cybersecurity solutions identify which devices should be trusted and which should be blocked. Devices that have a known association with malware or spam are known as malicious or suspicious IPs.
One of the most critical factors in identifying malicious or suspicious IP addresses is IP reputation. This tracks what the IP has done in the past and evaluates it for trustworthiness. If the IP has previously sent messages that have been repeatedly identified as spam or has hosted malware, there’s a high likelihood that it will be identified as malicious.
The more you know about malicious IPs, the easier it is to train your firewall and cybersecurity solution to repel them effectively without slowing down your network traffic.
What is a Malicious IP?
A malicious IP is any IP address that has been positively associated with malicious activity. Most firewalls and cybersecurity tools use a metric called IP reputation, which evaluates an IP’s trustworthiness using parameters and characteristics like:
- IP age
- Domain reputation
- Presence of downloadable files or code
- Any associated URL reputation
- Previous or current association with known malicious internet objects
- Hosting location
- Presence on any existing allow or blocklists
After it has been analyzed, IP reputation should offer an accurate assessment of the risks posed by an individual IP address.
Types of Malicious IPs
There are a few ways that an IP address can be confirmed as suspicious. Launching a distributed denial-of-service attack, dropping malware, hosting phishing sites, or hosting criminally illegal or obscene material are all common ways for an IP to get classified as malicious.
Below are some of the most common types of malicious IPs present on the internet today.
- Anonymous proxy: An IP address that is shielded using a VPN or other anonymizer to hide the original IP address.
- Botnets: An IP address that is infected with malware or other malicious software and is being controlled by another entity to attack other systems.
- Denial-of-service: This is an IP address that has a known history of launching any type of denial-of-service or anomalous traffic attack. These attacks target a website with a swarm of fake users or traffic, shutting down service for legitimate users.
- Illegal websites: If a website is currently hosting material that is illegal, it will be marked as a malicious IP. This includes anything from intellectual property violations to criminally obscene or unlawful material.
- Infected sources: An IP address that is distributing malware, viruses, or other infectious code.
- Phishing proxy: An IP that is hosting a website with active phishing or other fraudulent activity.
- Scanners: An IP address that is involved in any sort of attempt to scan or probe other domains for vulnerabilities that they can exploit.
How to Detect Suspicious IP Addresses?
Many companies use a prefabricated blacklist of IP addresses to ‘teach’ their firewall which IPs are trustworthy. However, a 2015 study from Recorded Future found that 92% of all suspicious IPs in existence are not currently blacklisted.
The best way to detect a malicious or suspicious IP address is to evaluate the IP reputation. This is usually a reliable indicator of the legitimacy of the IP in question. Being able to use IP reputation to detect suspicious or malicious IP addresses layers on an additional level of security, since it can evaluate the IP’s history of spam, bad associations, suspicious behavior, and even whether it’s hosted or originating in a location that has a history of cybercrime.
Fortunately, there are many free tools available that can help you evaluate IP reputation. We host a robust IP reputation tool on our website and offer it to anyone free of charge.
How to Defend Against Suspicious IPs
While free IP reputation tools can help you evaluate individual IP addresses that you come in contact with, doing it on a network level can be complex. The best way to defend your system against suspicious IPs is to do it proactively. Understanding this threat and mounting a defense against it makes it much easier to keep your system safe.
Here are a few tips you can use to get started.
Use a firewall that can identify suspicious IPs and proactively block them
The single most important thing that an organization can do to prevent malicious IP addresses from gaining access to their system is installing a firewall solution that can identify suspicious IPs and proactively block them. Most firewalls and cybersecurity software operate with a baseline level of IP reputation knowledge to help you get started, but these characteristics change often.
Keep your software updated
To ensure your firewall is working with the most current knowledge on malicious IPs, you will need to keep your software updated. The best software provides regular updates, and installing them is the only way to benefit from the company’s newly developed features, fixes, and upgrades. Failing to install these updates can leave even the most sophisticated system vulnerable.
Set up a good IP blocklist
Many organizations and tools have developed IP reputation lists as well as malicious IP databases. Accessing these blacklists and using them with your firewall can help exclude unwanted IP addresses. However, bad actors change their IPs all the time. Using a tool that can help cross-check external lists and regularly update your firewall blacklist will help ensure you’re working with the most up-to-date information.
Active Defenses Protect Against Suspicious IPs
The best defense is a good offense when you’re trying to protect your company data and digital infrastructure from bad actors. Being proactive against malicious IP addresses is easiest through a combination of comprehensive blacklists, regular software updates, and an excellent firewall defense system.
If you aren’t sure how your current firewall can handle our evolving landscape of threats, try Threater. Threater works as an extra layer on your firewall for seamless security. It combines in-depth threat intelligence from multiple sources and weaves them together into a comprehensive umbrella of protection over your entire technology stack.
Want to see how it works for yourself? Call us today to request a demo.