Rewterz Threat Alert – GraphSteel and GrimPlant Malware – Active IOCs – Russian-Ukrainian Cyber Warfare

Severity

High

Analysis Summary

GraphSteel and GrimPlant Backdoors have been used in conducting cyberattacks on Ukrainian authorities. The backdoors allow threat actors to gain unauthorized access and control of the victim’s system. Government agencies in Ukraine received emails with the topic “Wage arrears” or “Заборгованість по зарплаті” with an excel file of the same name. While the file does contain legitimate statistics, it is also contains hex-coded data and macros. Once the macro is executed, it will decode the data, create a new executable file “Base-Update.exe” on the computer and execute it.

This file is a downloader developed using the GoLang programming language. The program will download and run another bootloader, which, in turn, will download and run malware GraphSteel and GrimPlant on your computer. – CERT-UA

These attacks have been attributed to UAC-0056 aka UNC2589, TA471, or SaintBear.

Impact

• Information Theft and Espionage
• Exposure of Sensitive Data

Indicators of Compromise

Filename

• Wage arrears[.]xls
• Заборгованість по зарплаті[.]xls
• Base-Update[.]exe (GoDownloader)
• java-sdk[.]exe (GoDownloader)
• microsoft-cortana[.]exe (GraphSteel)

MD5

• da305627acf63792acb02afaf83d94d1
• 06124da5b4d6ef31dbfd7a6094fc52a6
• 36ff9ec87c458d6d76b2afbd5120dfae
• 6b413beb61e46241481f556bb5cdb69c

SHA-256

• c1afb561cd5363ac5826ce7a72f0055b400b86bd7524da43474c94bc480d7eff
• 9e9fa8b3b0a59762b429853a36674608df1fa7d7f7140c8fccd7c1946070995a
• 8ffe7f2eeb0cbfbe158b77bbff3e0055d2ef7138f481b4fac8ade6bfb9b2b0a1
• c83d8b36402639ea3f1ad5d48edc1a22005923aee1c1826afabe27cb3989baa3

SHA-1

• b4100aad572f619632ec28042a76c52ba2350acc
• 265a613ac405e6c3557e36a19f0ead2d18638cb0
• 9a3161c8570f1ca410038bed6e2aa297aebaf548
• 189f1879fcac60030dd3a751daae46a7444245f

URL

• http[:]//194[.]31[.]98[.]124[:]443/i
• http[:]//194[.]31[.]98[.]124[:]443/p
• http[:]//194[.]31[.]98[.]124[:]443/m

Remediation

• Block all threat indicators at your respective controls.
• Search for IOCs in your environment.
• Do not open emails from unknown or suspicious sources.