We closely monitor changes in the tactics of various cybercriminal groups. Recently, experts from Kaspersky’s Global Research and Analysis Team (GReAT) noted that, after attacks with Fog ransomware, malefactors were publishing not only victim’s data, but also the IP addresses of the attacked computers. We haven’t seen this tactic used by ransomware groups before. In this post, we explain why it’s important and what the purpose of this tactic is.

Who is the Fog ransomware group, and what’s it known for?

Since the ransomware business began to turn into a full-fledged industry, the involved cybercriminals have been splitting themselves up into various specializations. Nowadays, the creators of the ransomware and the people directly behind the attacks are most often not connected in any way — the former develop the malware along with a platform for attacks and subsequent blackmailing, while the latter simply buy access to the code and infrastructure under the ransomware-as-a-service (RaaS) model.

Fog ransomware is one such platform — first noticed in early 2024. The malware is used to attack computers running either Windows or Linux. As is customary among ransomware operators in recent years, the affected data is not only encrypted, but also uploaded to the attackers’ servers, and then, if the victim refuses to pay, published on a TOR site.

Attacks using Fog were carried out against companies working in the fields of education, finance, and recreation. Often, criminals used previously leaked VPN access credentials to penetrate the victim’s infrastructure.

Why they are publishing IP addresses?

Our experts believe that the main purpose of publishing IP addresses is to increase the psychological pressure on victims. Firstly, it increases the traceability and visibility of an incident. The effect of publishing the name of a victim company is less impressive, while the IP address can quickly tell not only who the victim was — but also what exactly was attacked (whether it was a server or a computer in the infrastructure). And the more visible the incident, the more likely it is to face lawsuits over data leakage and fines from regulators. Therefore, it’s more likely that the victim will make a deal and pay the ransom.

In addition, publishing an IP address sends a signal to other criminal groups, which can use the leaked data. They become aware of the address of a knowingly vulnerable machine, and have access to the information downloaded from it, which can be studied and used for further attacks on the infrastructure of the same company. This, in turn, makes the consequences of publication even more unpleasant, and therefore becomes an additional deterrent to ignoring the blackmailer’s demands.

How to stay safe

Since most ransomware attacks still start with employee error, we first recommend periodically raising staff awareness about modern-day cyberthreats (for example, using the online training platform.)

In order not to lose access to critical data, we, as usual, recommend making backups and keeping them in storage isolated from the main network. To prevent the ransomware from running on the company’s computers, it’s necessary that each corporate device with access to the network be equipped with an effective security solution. We also recommend that large companies monitor activity in the infrastructure using an XDR class solution, and, if necessary, involve third-party experts in detection and response activities.

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