Reconnaissance in cybersecurity: Everything you need to know

What is cybersecurity reconnaissance?

Cybersecurity reconnaissance is the first phase of a cyberattack, during which threat actors gather initial information about a target network. This stage of a cyberattack helps reveal potential vulnerabilities in a target’s systems or networks and how to exploit them. Cyberattacks can have devastating results, such as data breaches, financial losses, and damage to your or your company’s reputation. So, when facing cyber threats like reconnaissance, it’s important to use both defensive and offensive tactics to prevent them. 

Types of cybersecurity reconnaissance attacks

In this section, we’ll discuss the types of reconnaissance attacks: passive and active reconnaissance.

Passive reconnaissance

Passive reconnaissance in cybersecurity, also known as passive network reconnaissance or open source intelligence (OSINT), is a form of reconnaissance where hackers gain information without interacting with the target system or network.

During the passive reconnaissance process, cybercriminals often gather data from publicly available sources like social media platforms and WHOIS. WHOIS is a public database that offers information about who owns domain names and IP addresses. Many hackers discover a company's public IP address range through WHOIS lookups. They also practice dark web monitoring, which involves collecting data on a target on dark web marketplaces and forums.

A big advantage of passive information gathering over active reconnaissance is that a hacker can gain information about a target network with little risk of getting caught. Thanks to its covert nature, passive reconnaissance can continue for a long time without being detected.

However, since passive reconnaissance doesn’t involve interacting with the target’s operating system, cybercriminals using this type of reconnaissance often miss out on valuable information about a system’s access points and other vulnerabilities.

That’s not to say that hackers can’t do much damage with passive reconnaissance. A threat actor can learn a lot without coming anywhere near a target — their name, social media accounts, address, and phone number. 

Active reconnaissance

Active reconnaissance in cybersecurity involves the hacker actively engaging with the target. Cybercriminals use several active reconnaissance techniques like automated scanning to scan large networks and gain access to valuable data in an active network reconnaissance attack. Port scanning allows them to identify open ports and the network services running on a host. Ping sweeps detect which IP addresses are associated with live hosts on a network. Banner grabbing acquires details about a computer’s operating system and services.

Interacting directly with a potential victim’s operating system can provide the hacker with more targeted analysis than passive reconnaissance. However, the risk of using active reconnaissance is much higher. If a hacker gets caught violating any laws or regulations related to privacy and/or unauthorized computer access, they could face hefty fines and even jail time.

Luckily, some use their hacking powers for good. Ethical hacking practices involve using hacking techniques to detect security vulnerabilities in a network or computer system that an attacker could use to exploit an individual or organization.

Reconnaissance is the first step of penetration testing, where ethical hackers simulate a cyberattack to identify vulnerabilities in a system. They also perform manual testing, where a human tester manually interacts with a system by trying different inputs, attack vectors, and scenarios to reveal vulnerabilities.

How does cybersecurity reconnaissance work?

So, how exactly does reconnaissance work? With passive and active reconnaissance, hackers use automated tools and techniques to gather information about a target network or system.

• Footprinting. Although the terms footprinting and cyber reconnaissance are often used interchangeably, footprinting refers specifically to methods used in passive information gathering.
• Enumeration. While footprinting collects data without direct interaction with the target, enumeration refers to methods used in active information gathering.
• Operating system (OS) fingerprinting. OS fingerprinting determines which OS a remote computer is running. OS fingerprinting is an effective tool since most vulnerabilities hackers can exploit are operating system-specific.
• Network mapping. Using this process, a hacker can view the connections between a network’s services and endpoints. It includes locating routers and ports.
• Network scanning. Network scanning is a technique hackers use to detect active hosts on a network and their IP addresses.
• Port scanning. Hackers use port scanning techniques to locate open ports on a computer network that could be exploited and identify services running on them. Port scanning involves examining IP addresses and searching for vulnerabilities. 

Hackers use these reconnaissance techniques to collect data and commit cybercrimes against their victims. However, individuals and organizations can use these same reconnaissance tools to defend against cyber threats. By mimicking a hacker’s behavior, ethical hackers can detect the same vulnerabilities hackers would and take action to fix them while gaining more threat intelligence.

Threat intelligence refers to security professionals analyzing reconnaissance data to identify and understand potential insider threats and other vulnerabilities in an organization. They use this reconnaissance data to build a threat intelligence profile, which helps an organization make important cybersecurity decisions. Reconnaissance data can also inform an intrusion detection system and help detect vulnerabilities in the network that attackers could exploit against a company’s devices and systems.

How to prevent cybersecurity reconnaissance

As a result of reconnaissance, hackers could install malware on your device or gain access to your bank accounts. Fortunately, you can employ security measures to protect yourself and your company from reconnaissance attacks.

• Network monitoring. Network monitoring is a great way to protect yourself and your company from reconnaissance attempts. Check and analyze your network traffic to see if there’s been any suspicious activity like port scanning or network mapping. You can use network monitoring software to monitor your network traffic.
• Asset inventory. Keeping an updated asset inventory makes it easier to see that all your assets are accounted for and any issues become more obvious. Like with network monitoring, you can use software tools to help you perform asset inventory.
• Vulnerability scanning. This tool helps to identify potential cyber risks across your organization’s hardware, software, networks, and computer systems. You can use vulnerability scanners to help you carry out vulnerability scanning.
• IDS and IDPS. As mentioned, intrusion detection systems (IDS) can help to protect you from cyber reconnaissance. They identify potential threats and issue alerts, while intrusion prevention systems (IDPS) actively block or prevent those threats from causing harm. Both these tools will help to prevent cyber reconnaissance.
• A honeypot. A honeypot is a bait you can use to lure hackers in so you can learn more about potential cyber threats and monitor the hackers’ behavior. It’s a fake computer system designed to attract attackers and trick them into interacting with it through a reconnaissance attack.
• Firewall rules. In addition to blocking malicious network traffic like a phishing attack, you can set up your firewall rules to allow only necessary traffic and block unnecessary ports. You can also use access controls to manage who has network access.
• Patch management. Patch management keeps software and systems up-to-date with the latest security patches, closing gaps in your security that hackers could have exploited.
• Data masking. Data masking is a technique for protecting your data at rest from reconnaissance attackers. It involves replacing sensitive data with fake or scrambled data to make it harder for unauthorized users to access it.

If you don’t have the budget to spring for expensive software and tools to combat reconnaissance, don't worry. NordVPN’s blog is chock full of advice to help you defend yourself from reconnaissance attackers. For example, you can find tips on creating a strong password that will make it harder for hackers to gather information. You can also brush up on safe browsing practices to stay safer online.