# Netskope Threat Coverage: WhisperGate

**[netskope.com/blog/netskope-threat-coverage-whispergate](https://www.netskope.com/blog/netskope-threat-coverage-whispergate)**

Gustavo Palazolo January 26, 2022

## Summary

[A new destructive malware called WhisperGate](https://malpedia.caad.fkie.fraunhofer.de/details/win.whispergate) [was discovered in mid-January 2022](https://www.microsoft.com/security/blog/2022/01/15/destructive-malware-targeting-ukrainian-organizations/)
[targeting Ukrainian organizations. This threat emerged during geopolitical conflicts in](https://thehackernews.com/2022/01/ukrainian-government-officially-accuses.html)
Ukraine, masquerading as ransomware. However, this malware has a more destructive
nature: wiping files and corrupting disks to prevent the OS from loading. Ukraine has
suffered other cyberattacks that seem to be connected to WhisperGate, such as the
[defacement of many websites connected to their governments.](https://www.washingtonpost.com/national-security/ukraine-russia-cyberattacks/2022/01/18/79590750-78a1-11ec-bf97-6eac6f77fba2_story.html)

This is a multi-stage malware, where one of the payloads is hosted on a Discord server. The
preference of attackers to use cloud services for malicious purposes is increasingly common,
as pointed out in an analysis of a threat campaign that uses multiple cloud services
[throughout the attack. The threat group behind WhisperGate is being tracked as DEV-0586,](https://bazaar.abuse.ch/browse/tag/DEV-0586/)
and so far there isn’t any association between this attack to known APT groups. In this threat
coverage, we analyzed all four stages of WhisperGate to demonstrate how it works.

## Analysis

### Stage 01


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WhisperGate s first stage is a small executable compiled with MinGW, responsible for
[corrupting the disk by writing code into the Master Boot Record (MBR), which is a small](https://www.ntfs.com/mbr.htm)
section on disk that contains the Partition Table and an executable code related to the boot
loader.

Binary information about WhisperGate’s first stage
[Corrupting the MBR is a simple technique to prevent any Operating System from loading, as](https://www.ntfs.com/mbr-virus.htm)
the assembly code is executed before the OS.

The entire code for the first stage of WhisperGate can fit in a single screenshot, where the
malware loads the MBR data that will be written to disk, opens a handle to the physical drive
with CreateFileW, and uses WriteFile to writes the 512 bytes to MBR, which is located in the
first sector of the disk.


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Disassembled code of WhisperGate’s first stage.
The MBR stub written to disk includes a 16-bit assembly code and a message.


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Data written on disk by WhisperGate
If we load this data into the disassembler, we can analyze the 16-bit assembly that will be
executed once the computer is rebooted, which doesn’t do anything but display a message.

Code that is executed once the computer is infected with WhisperGate.
Once the computer is infected, as soon as it restarts, the message is displayed and the OS
is prevented from loading. The message says the hard drive was corrupted and demands a
payment of $10,000 via Bitcoin to a specific walled address.


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Computer infected with the first stage of WhisperGate.
This is the only action performed by the first stage of WhisperGate. The following stages
were created probably to add a certain resilience to the attack in case the first stage fails, as
systems may use [GUID Partition Table (GPD), which is MBR’s successor.](https://www.ntfs.com/guid-part-table.htm)

### Stage 02

In this stage, we have a simple .NET downloader for stage 03. The binary contains an
expired signature from Microsoft, and although it is not shown by identification tools, the file
is obfuscated with NetReactor, as pointed out by [OALabs.](https://github.com/OALabs/Lab-Notes/blob/main/WhisperGate/WhisperGate.ipynb)

Binary information about WhisperGate’s second stage.
Once running, it downloads the third stage from a Discord server, named “Tbopbh.jpg”.


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WhisperGate’s .NET downloader.
After the download, the malware loads the binary as a .NET assembly and executes the
method named “Ylfwdwgmpilzyaph”.

Malware executing

the third stage of WhisperGate

### Stage 03

Here we have a 32-bit DLL, also developed in .NET. Since this file is directly loaded by the
second stage as a .NET assembly, the DLL doesn’t have an entry point, which requires
some adjustments to make dynamic analysis feasible.


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Binary information about WhisperGate’s third stage.
As shown in the image above, the file is protected with Eazfuscator, likely to hinder
researchers’ analysis. Searching throughout the decompiled code, we can find the same
method that is executed by the second stage.

Main function from the third stage of WhisperGate.
Once running, it checks if the process is running as an Administrator. If it’s not the case, it
launches itself with elevated permissions and exits the process.

Malware checking for administrative permissions.
Then, it drops a VBS named “Nmddfrqqrbyjeygggda.vbs” into the Windows temporary
folder, containing a simple PowerShell code that adds the path “C:\” to Windows Defender’s
exclusion list.


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Simple VBS / PowerShell to bypass Windows Defender.
It also drops an executable named “AdvancedRun.exe” to the same directory, which is a
[tool from NirSoft to execute programs with different settings. WhisperGate uses this tool to](https://www.nirsoft.net/utils/advanced_run.html)
execute commands in the “TrustedInstaller” group context.

Usage of AvancedRun tool, by NirSoft.
It executes two commands with this tool, both as an attempt to disable Windows Defender.
The first one tries to stop Defender’s service, and the second tries to delete its respective
folder.

Commands executed with AdvancedRun.
Then, WhisperGate copies “InstallUtil.exe” to Windows temporary folder, which is a binary
from .NET Framework.

Copying InstallUtil executable to Windows temporary folder.
And finally, WhisperGate’s last stage is injected into an instance of the InstallUtil’s process.
The payload is stored within an encrypted resource, where all the bytes are reversed and
[compressed with Gzip.](https://www.gnu.org/software/gzip/)


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Malware loading WhisperGate’s last stage.

### Stage 04

The binary used in this stage is quite similar to the first one in terms of compiler and linker.

WhisperGate’s last stage.
Looking at the main function of the malware, we have two functions being called prior to the
end of the execution.


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_WhisperGate’s main function._

At the function we named “mw_main_routine”, the malware starts by listing the drives with
[the help of GetLogicalDrives API.](https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-getlogicaldrives)

Malware listing OS drives.

Then, it uses [GetDriveTypeW to check if the drive is either fixed or remote. If that’s the case,](https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-getdrivetypew)
it starts the function that will wipe the files.


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Malware checking the

drive type.
Within the function we named “mw_wipe_files”, it starts by listing all the files in the root path
[of the drive with FindFirstFileW.](https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-findfirstfilew)


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Malware listing all the files

in the current directory.
If the current object is a directory, the “mw_wipe_files” function is called recursively with the
identified directory as a parameter. This is verified by calling the “_wstat” function and
[checking the st_mode bits.](https://docs.microsoft.com/en-us/previous-versions/visualstudio/visual-studio-2013/14h5k7ff(v=vs.120))

Malware checking if the current object is a directory.
WhisperGate does not wipe files in the Windows directory.


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WhisperGate

skipping Windows folder.
The last verification is related to the file’s extension, where the malware iterates over a list of
targeted extensions and, if the file name matches, a function we named
“mw_write_bytes_to_file” is called.


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WhisperGate checking for targeted extensions.
WhisperGate targets many files with extensions related to websites, such as “.html”, “.php”,
“.asp”, “.jsp”, as well as common documents like “.doc”, “.xls”, “.ppt”, etc. A complete list of
[targeted extensions can be found in our GitHub repository.](https://github.com/netskopeoss/NetskopeThreatLabsIOCs/tree/main/WhisperGate/IOCs)


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WhisperGate’s targeted extensions.

And finally, if the file matches the criteria, WhisperGate wipes the file by replacing its content
with a sequence of 0x100000 bytes of 0xCC.

WhisperGate wiping system’s

files.
Also, a random extension is appended to the file’s name.


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Files wiped by WhisperGate.
Once it’s over, WhisperGate deletes itself through a simple command line, where “%s” is the
[file path obtained with GetModuleFileNameA.](https://docs.microsoft.com/en-us/windows/win32/api/libloaderapi/nf-libloaderapi-getmodulefilenamea)

This is the only behavior of WhisperGate’s last stage. Paying the ransom demanded would
be fruitless because the MBR and files were simply overwritten, not encrypted like they
would be by ransomware.

## Conclusions

WhisperGate is a multi-stage destructive malware that has emerged in the midst of the
[geopolitical conflict that is still unfolding in Ukraine. Netskope Threat Labs is on the lookout](https://www.washingtonpost.com/politics/2022/01/04/fears-mount-about-russian-cyberattacks-ukraine/)
for any malware that may appear with an apparent political motivation, especially ones that
may disrupt essential services, such as infrastructure. It’s also interesting to see this threat
using Discord to host one of the payloads, showing again the preference of cloud apps
[usage by cyber attackers. We echo CISA’s recommendations released in this note to](https://www.cisa.gov/sites/default/files/publications/CISA_Insights-Implement_Cybersecurity_Measures_Now_to_Protect_Against_Critical_Threats_508C.pdf)
implement cybersecurity measures for critical infrastructure.

## Protection

Netskope Threat Labs is actively monitoring this campaign and has ensured coverage for all
known threat indicators and payloads.

**Netskope Threat Protection**

Win32.Trojan.WhisperGate
Win32.Network.WhisperGate
ByteCode-MSIL.Trojan.WhisperGate


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**Netskope Advanced Threat Protection provides proactive coverage against this**
threat.

Gen.Malware.Detect.By.StHeur indicates a sample that was detected using static
analysis
Gen.Malware.Detect.By.Sandbox indicates a sample that was detected by our
cloud sandbox

## IOCs

[A full list of IOCs and Yara rules can be found in our GitHub repository.](https://github.com/netskopeoss/NetskopeThreatLabsIOCs/tree/main/WhisperGate)


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