Kapeka: A novel backdoor spotted in Eastern Europe

WithSecure has uncovered a novel backdoor that has been used in attacks against victims in Eastern Europe since at least mid-2022.

The malware, which we are calling "Kapeka", is a flexible backdoor with all the necessary functionalities to serve as an early-stage toolkit for its operators, and also to provide long-term access to the victim estate. The malware's victimology, infrequent sightings, and level of stealth and sophistication indicate APT-level activity.

WithSecure discovered overlaps between Kapeka, GreyEnergy, and Prestige ransomware attacks which are all reportedly linked to a group known as Sandworm. WithSecure assesses it is likely that Kapeka is a new addition to Sandworm’s arsenal. Sandworm is a prolific Russian nation-state threat group operated by the Main Directorate of the General Staff of the Armed Forces of the Russian Federation (GRU). Sandworm is particularly notorious for its destructive attacks against Ukraine in pursuit of Russian interests in the region.

Kapeka contains a dropper that will drop and launch a backdoor on a victim’s machine and then remove itself. The backdoor will first collect information and fingerprint both the machine and user before sending the details on to the threat actor. This allows tasks to be passed back to the machine or the backdoor’s configuration to be updated. WithSecure do not have insight as to how the Kapeka backdoor is propagated by Sandworm.

Kapeka’s development and deployment likely follow the ongoing Russia-Ukraine conflict, with Kapeka being likely used in targeted attacks of firms across Central and Eastern Europe since the illegal invasion of Ukraine in 2022. 

It is likely that Kapeka was used in intrusions that led to the deployment of Prestige ransomware in late 2022. It is probable that Kapeka is a successor to GreyEnergy, which itself was likely a replacement for BlackEnergy in Sandworm’s arsenal.

This report provides an in-depth technical analysis of the backdoor and its capabilities, and analyzes the connection between Kapeka and Sandworm group. The purpose of this report is to raise awareness amongst businesses, governments, and the broader security community. WithSecure has engaged governments and select customers with advanced copies of this report. In addition to the report, we are releasing several artifacts developed as a result of our research, including a registry-based & hardcoded configuration extractor, a script to decrypt and emulate the backdoor’s network communication, and as might be expected, a list of indicators of compromise, YARA rules, and MITRE ATT&CK mapping.


23.04.2024 - Design and formatting of the report have been updated. Figure 37 has been updated as well to more clearly represent our understanding of the links between events.