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whispergate

First posted on 15 August 2023.
Source: SecurityHome

Aliases :

whispergate is also known as DEV-0586.

Explanation :

On January 13, 2022, Microsoft identified intrusion activity originating from Ukraine that appeared to be possible Master Boot Records (MBR) Wiper activity. During our investigation, we found a unique malware capability being used in intrusion attacks against multiple victim organizations in Ukraine.

Stage 1: Overwrite Master Boot Record to display a faked ransom note
The malware resides in various working directories, including C:PerfLogs, C:ProgramData, C:, and C: emp, and is often named stage1.exe. In the observed intrusions, the malware executes via Impacket, a publicly available capability often used by threat actors for lateral movement and execution.

The two-stage malware overwrites the Master Boot Record (MBR) on victim systems with a ransom note (Stage 1). The MBR is the part of a hard drive that tells the computer how to load its operating system. The ransom note contains a Bitcoin wallet and Tox ID (a unique account identifier used in the Tox encrypted messaging protocol) that have not been previously observed by MSTIC:

Your hard drive has been corrupted.
In case you want to recover all hard drives
of your organization,
You should pay us $10k via bitcoin wallet
1AVNM68gj6PGPFcJuftKATa4WLnzg8fpfv and send message via
tox ID 8BEDC411012A33BA34F49130D0F186993C6A32DAD8976F6A5D82C1ED23054C057ECED5496F65
with your organization name.
We will contact you to give further instructions.


The malware executes when the associated device is powered down. Overwriting the MBR is atypical for cybercriminal ransomware. In reality, the ransomware note is a ruse and that the malware destructs MBR and the contents of the files it targets. There are several reasons why this activity is inconsistent with cybercriminal ransomware activity observed by MSTIC, including:

• Ransomware payloads are typically customized per victim. In this case, the same ransom payload was observed at multiple victims.


• Virtually all ransomware encrypts the contents of files on the filesystem. The malware in this case overwrites the MBR with no mechanism for recovery.


• Explicit payment amounts and cryptocurrency wallet addresses are rarely specified in modern criminal ransom notes, but were specified by DEV-0586. The same Bitcoin wallet address has been observed across all DEV-0586 intrusions and at the time of analysis, the only activity was a small transfer on January 14.


• It is rare for the communication method to be only a Tox ID, an identifier for use with the Tox encrypted messaging protocol. Typically, there are websites with support forums or multiple methods of contact (including email) to make it easy for the victim to successfully make contact.


• Most criminal ransom notes include a custom ID that a victim is instructed to send in their communications to the attackers. This is an important part of the process where the custom ID maps on the backend of the ransomware operation to a victim-specific decryption key. The ransom note in this case does not include a custom ID.

Stage 2: File corrupter malware
Stage2.exe is a downloader for a malicious file corrupter malware. Upon execution, stage2.exe downloads the next-stage malware hosted on a Discord channel, with the download link hardcoded in the downloader. The next-stage malware can best be described as a malicious file corrupter. Once executed in memory, the corrupter locates files in certain directories on the system with one of the following hardcoded file extensions:
.3DM .3DS .7Z .ACCDB .AI .ARC .ASC .ASM .ASP .ASPX .BACKUP .BAK .BAT .BMP .BRD .BZ .BZ2 .CGM .CLASS .CMD .CONFIG .CPP .CRT .CS .CSR .CSV .DB .DBF .DCH .DER .DIF .DIP .DJVU.SH .DOC .DOCB .DOCM .DOCX .DOT .DOTM .DOTX .DWG .EDB .EML .FRM .GIF .GO .GZ .HDD .HTM .HTML .HWP .IBD .INC .INI .ISO .JAR .JAVA .JPEG .JPG .JS .JSP .KDBX .KEY .LAY .LAY6 .LDF .LOG .MAX .MDB .MDF .MML .MSG .MYD .MYI .NEF .NVRAM .ODB .ODG .ODP .ODS .ODT .OGG .ONETOC2 .OST .OTG .OTP .OTS .OTT .P12 .PAQ .PAS .PDF .PEM .PFX .PHP .PHP3 .PHP4 .PHP5 .PHP6 .PHP7 .PHPS .PHTML .PL .PNG .POT .POTM .POTX .PPAM .PPK .PPS .PPSM .PPSX .PPT .PPTM .PPTX .PS1 .PSD .PST .PY .RAR .RAW .RB .RTF .SAV .SCH .SHTML .SLDM .SLDX .SLK .SLN .SNT .SQ3 .SQL .SQLITE3 .SQLITEDB .STC .STD .STI .STW .SUO .SVG .SXC .SXD .SXI .SXM .SXW .TAR .TBK .TGZ .TIF .TIFF .TXT .UOP .UOT .VB .VBS .VCD .VDI .VHD .VMDK .VMEM .VMSD .VMSN .VMSS .VMTM .VMTX .VMX .VMXF .VSD .VSDX .VSWP .WAR .WB2 .WK1 .WKS .XHTML .XLC .XLM .XLS .XLSB .XLSM .XLSX .XLT .XLTM .XLTX .XLW .YML .ZIP

If a file carries one of the extensions above, the corrupter overwrites the contents of the file with a fixed number of 0xCC bytes (total file size of 1MB). After overwriting the contents, the destructor renames each file with a seemingly random four-byte extension. Analysis of this malware is ongoing.

Last update 15 August 2023

 

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