Hackers use WinRAR as a Cyberweapon to Conduct Destructive Cyberattacks

CERT-UA (Ukrainian Government Computer Emergency Response Team) recently reported that the Ukrainian state networks suffered a cyber attack attributed to the notorious ‘Sandworm’ hacking group from Russia.

The attackers reportedly employed WinRar to destroy critical data on various government devices.

Russian hackers successfully infiltrated critical systems in Ukrainian state networks by exploiting compromised VPN accounts that lacked adequate protection from multi-factor authentication measures.

Upon gaining unauthorized access to the targeted network, the perpetrators utilized specialized scripts that wiped out critical data on Windows and Linux systems. 

Their method of choice was the WinRar archiving program, which was exploited to carry out the devastating attacks.

Filetypes Targeted

The Sandworm hacking group employed a BAT script called ‘RoarBat,’ to perform malicious operations on Windows devices. 

This script was designed to scan various disks and targeted directories, seeking out specific file types like:-

doc, docx, rtf, txt, xls, xlsx, ppt, pptx, vsd, vsdx, pdf, png, jpeg, jpg, zip, rar, 7z, mp4, SQL, PHP, vbk, vib, vrb, p7s, sys, DLL, exe, bin, dat

The attackers employed a specific tactic when utilizing WinRar, using the “-df” command-line option. 

This feature automatically deletes files as they are being archived, thus allowing the perpetrators to destroy critical data with ease systematically.

Following the archive process, the perpetrators went further and deleted the archives themselves. 

As per CERT-UA, the RoarBAT script was executed through a scheduled task centrally created and distributed across all devices on the Windows domain.

This distribution was facilitated using group policies, which allowed for seamless task implementation across the entire network.

The attackers opted for a different approach when targeting Linux machines, utilizing a Bash script instead of the BAT script employed on Windows systems. 

This script used the “dd” utility to overwrite specific file types with zero bytes, rendering the data completely irretrievable.

Given the nature of data replacement carried out by the dd tool, the likelihood of recovering files that have been “emptied” using this method is extremely low. 

It may even be impossible to restore the contents of the affected files. Using legitimate programs such as the ‘dd’ command and WinRar was likely a strategic move by the threat actors to evade detection by AV tools.

According to CERT-UA, the recent cyber attack on Ukrainian state networks resembles a similar incident that occurred in January 2023.

In light of recent events, CERT-UA has issued recommendations to help critical organizations nationwide mitigate the risk of similar cyber attacks.

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