You spend your days getting ready to stop threat actors. But even as you wonder, attackers could already be ‘casing the joint’.

Before any well-organized attack, skillful or professional attackers quietly snoop around, looking for chances to gain access. It’s called malicious reconnaissance — the unauthorized active monitoring or probing of any information system to discover security vulnerabilities.

The frequency of these events is way, way up in the past few years. IBM’s X-Force Threat Intelligence Index 2022 reported that malicious reconnaissance of the supervisory control and data acquisition Modbus protocol for operational technology devices increased 2,204% between January and September of 2021.

This increase suggests that, in general, attackers and state-sponsored actors are becoming more skilled and professional in their methods.

How malicious reconnaissance works

A systematic malicious reconnaissance campaign seeks to find all the vulnerabilities in a system. The attacker will do this before they engage with the network, exfiltrate business data or interact with running services or open ports. In fact, it comes before they do anything that’s more likely to trigger defensive measures by the victim.

Malicious reconnaissance isn’t a breach, exploit or attack. Many organizations aren’t actively detecting it. And that’s why attackers value it. By increasing the number of known entryways, malicious actors can move very quickly when they do launch their attack.

Such recon can take hours, days or months. As the intruders become more familiar with the systems, the process can evolve from discovering to re-checking the status of known points of vulnerability to make sure they still exist.

Open-source intelligence (OSINT) is another major method for malicious reconnaissance. Potential attackers can scan public information in the media or on the internet, including social media.

State-sponsored malicious reconnaissance often seeks complete knowledge of vulnerabilities to be exploited later during negotiations, political tensions or full-scale cyber warfare. Just as military planners stage war games, map out possible scenarios and study their rivals, nation-states do heavy reconnaissance to prepare for future cyber conflict. Targets can include just about any agency, utility or private company.

How to protect your data

If you can discover malicious reconnaissance, it can serve as a chance to prevent an attack.

Reconnaissance is a major element of pen testing and red teaming. By seeking out vulnerabilities during pen testing, you can learn where to look for threats. In other words, major parts of pen testing and red-teaming involve malicious reconnaissance tests. That way, you can learn what attackers could learn.

It also makes sense to review what you can learn from OSINT. Know what people searching for your organization on public databases and media and internet content will find. Think about potential ways they could use that knowledge to launch social engineering attacks.

You can also use cloud data and artificial intelligence tools that hunt for odd behavior on the network. These identify and understand malicious reconnaissance taking place in your cloud systems and networks. Anomaly detection is really the core practice of detecting potential malicious reconnaissance campaigns.

Once you have the data, find out what the campaign is after and, if possible, who is doing it, how long they’ve been doing it and why they might be doing it. And, of course, take action before attacks happen. Patch the software, closing the doorways through which the intruders can move around in the networks. Lastly, notify the authorities and keep tracking the threat.

Yes, they may be ‘casing the joint’. But you can case the casers, figure out what they’re up to and stop them before they strike.