Threat Signal Report

MicroBackdoor Used in Attacks Against Ukraine Organizations

description-logo Description

FortiGuard Labs is aware of a report from CERT-UA that Ukrainian organizations are under cyberattacks that aim to install a publicly available backdoor named "MicroBackdoor." The cyberattacks are attributed to APT group "UAC-0051", also known as unc1151, who has reportedly acted for Belarusian government's interests in the past.

Why is this Significant?

This is significant because, according to CERT-UA, Ukraine organizations were attacked by an APT group whose past activities are said to be aligned with Belarusian government's interests.

What's the Detail of the Attack?

Unfortunately, the initial attack vector is unknown. What's known is that the victims received "", which contains "dovidka.chm". The CHM file contains two files. An image.jpg is an image file used as a decoy. Another file is file.htm, which creates "ignit.vbs". The VBS file decodes three files: "core.dll," "desktop.ini" and "Windows Prefetch.lnk." The LNK file launches the INI file using wscript.exe. Then, the INI file runs the DLL using regasm.exe. The core.dll is a .NET loader that decodes and executes MicroBackdoor on the compromised machine.

What is MicroBackdoor?

MicroBackdoor is a publicly available backdoor that receives commands from a Command and Control (C2) server and performs various activities.

According to the description on the MicroBackdoor repository

"Micro Backdoor client supports 32-bit and 64-bit versions of Windows XP, Vista, 7, 8, 8.1, 10, Server 2003, Server 2003 R2, Server 2008, Server 2008 R2, Server 2012, Server 2012 R2, Server 2016 and Server 2019 of any editions, languages and service packs."

What is the Status of Coverage?

FortiGuard Labs provide the following AV coverage against available files involved in the attack:




All network IOCs are blocked by the WebFiltering client.




Traffic Light Protocol

Color When Should it Be used? How may it be shared?


Not for disclosure, restricted to participants only.
Sources may use TLP:RED when information cannot be effectively acted upon by additional parties, and could lead to impacts on a party's privacy, reputation, or operations if misused. Recipients may not share TLP:RED information with any parties outside of the specific exchange, meeting, or conversation in which it was originally disclosed. In the context of a meeting, for example, TLP:RED information is limited to those present at the meeting. In most circumstances, TLP:RED should be exchanged verbally or in person.


Limited disclosure, restricted to participants’ organizations.
Sources may use TLP:AMBER when information requires support to be effectively acted upon, yet carries risks to privacy, reputation, or operations if shared outside of the organizations involved. Recipients may only share TLP:AMBER information with members of their own organization, and with clients or customers who need to know the information to protect themselves or prevent further harm. Sources are at liberty to specify additional intended limits of the sharing: these must be adhered to.


Limited disclosure, restricted to the community.
Sources may use TLP:GREEN when information is useful for the awareness of all participating organizations as well as with peers within the broader community or sector. Recipients may share TLP:GREEN information with peers and partner organizations within their sector or community, but not via publicly accessible channels. Information in this category can be circulated widely within a particular community. TLP:GREEN information may not be released outside of the community.


Disclosure is not limited.
Sources may use TLP:WHITE when information carries minimal or no foreseeable risk of misuse, in accordance with applicable rules and procedures for public release. Subject to standard copyright rules, TLP:WHITE information may be distributed without restriction.