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Bisonal

Bisonal is a remote access tool (RAT) that has been used by Tonto Team against public and private sector organizations in Russia, South Korea, and Japan since at least December 2010.[1][2]

ID: S0268
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Type: MALWARE
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Platforms: Windows
Version: 2.1
Created: 17 October 2018
Last Modified: 11 April 2024
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Enterprise Layer
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Techniques Used

Domain ID Name Use
Enterprise T1071 .001 Application Layer Protocol: Web Protocols

Bisonal has used HTTP for C2 communications.[1][3]
Enterprise T1547 .001 Boot or Logon Autostart Execution: Registry Run Keys / Startup Folder

Bisonal has added itself to the Registry key HKEY_CURRENT_USER\Software\Microsoft\CurrentVersion\Run\ for persistence.[1][2]

Enterprise T1059 .003 Command and Scripting Interpreter: Windows Command Shell

Bisonal has launched cmd.exe and used the ShellExecuteW() API function to execute commands on the system.[1][3][2]
.005 Command and Scripting Interpreter: Visual Basic

Bisonal's dropper creates VBS scripts on the victim’s machine.[1][2]

Enterprise T1543 .003 Create or Modify System Process: Windows Service

Bisonal has been modified to be used as a Windows service.[2]

Enterprise T1132 .001 Data Encoding: Standard Encoding

Bisonal has encoded binary data with Base64 and ASCII.[3][2]

Enterprise T1005 Data from Local System

Bisonal has collected information from a compromised host.[2]

Enterprise T1140 Deobfuscate/Decode Files or Information

Bisonal has decoded strings in the malware using XOR and RC4.[1][2]

Enterprise T1568 Dynamic Resolution

Bisonal has used a dynamic DNS service for C2.[2]
Enterprise T1573 .001 Encrypted Channel: Symmetric Cryptography

Bisonal variants reported on in 2014 and 2015 used a simple XOR cipher for C2. Some Bisonal samples encrypt C2 communications with RC4.[1][3][2]

Enterprise T1041 Exfiltration Over C2 Channel

Bisonal has added the exfiltrated data to the URL over the C2 channel.[2]

Enterprise T1083 File and Directory Discovery

Bisonal can retrieve a file listing from the system.[3][2]

Enterprise T1070 .004 Indicator Removal: File Deletion

Bisonal will delete its dropper and VBS scripts from the victim’s machine.[1][3][2]
Enterprise T1105 Ingress Tool Transfer

Bisonal has the capability to download files to execute on the victim’s machine.[1][3][2]

Enterprise T1036 Masquerading

Bisonal dropped a decoy payload with a .jpg extension that contained a malicious Visual Basic script.[2]

.005 Match Legitimate Name or Location

Bisonal has renamed malicious code to msacm32.dll to hide within a legitimate library; earlier versions were disguised as winhelp.[2]

Enterprise T1112 Modify Registry

Bisonal has deleted Registry keys to clean up its prior activity.[2]

Enterprise T1106 Native API

Bisonal has used the Windows API to communicate with the Service Control Manager to execute a thread.[2]
Enterprise T1095 Non-Application Layer Protocol

Bisonal has used raw sockets for network communication.[2]
Enterprise T1027 .001 Obfuscated Files or Information: Binary Padding

Bisonal has appended random binary data to the end of itself to generate a large binary.[2]

.002 Obfuscated Files or Information: Software Packing

Bisonal has used the MPRESS packer and similar tools for obfuscation.[2]

.013 Obfuscated Files or Information: Encrypted/Encoded File

Bisonal's DLL file and non-malicious decoy file are encrypted with RC4 and some function name strings are obfuscated.[1][2]
Enterprise T1137 .006 Office Application Startup: Add-ins

Bisonal has been loaded through a .wll extension added to the %APPDATA%\microsoft\word\startup\ repository.[2]

Enterprise T1566 .001 Phishing: Spearphishing Attachment

Bisonal has been delivered as malicious email attachments.[2]

Enterprise T1057 Process Discovery

Bisonal can obtain a list of running processes on the victim’s machine.[1][3][2]
Enterprise T1090 Proxy

Bisonal has supported use of a proxy server.[2]
Enterprise T1012 Query Registry

Bisonal has used the RegQueryValueExA function to retrieve proxy information in the Registry.[2]
Enterprise T1218 .011 System Binary Proxy Execution: Rundll32

Bisonal has used rundll32.exe to execute as part of the Registry Run key it adds: HKEY_CURRENT_USER \Software\Microsoft\Windows\CurrentVersion\Run\"vert" = "rundll32.exe c:\windows\temp\pvcu.dll , Qszdez".[1]
Enterprise T1082 System Information Discovery

Bisonal has used commands and API calls to gather system information.[1][3][2]
Enterprise T1016 System Network Configuration Discovery

Bisonal can execute ipconfig on the victim’s machine.[1][3][2]

Enterprise T1124 System Time Discovery

Bisonal can check the system time set on the infected host.[3]
Enterprise T1204 .002 User Execution: Malicious File

Bisonal has relied on users to execute malicious file attachments delivered via spearphishing emails.[2]

Enterprise T1497 Virtualization/Sandbox Evasion

Bisonal can check to determine if the compromised system is running on VMware.[2]
.003 Time Based Evasion

Bisonal has checked if the malware is running in a virtual environment with the anti-debug function GetTickCount() to compare the timing.[3][2]

Groups That Use This Software

ID Name References
G0131 Tonto Team

[3][4][2]

References

  1. Hayashi, K., Ray, V. (2018, July 31). Bisonal Malware Used in Attacks Against Russia and South Korea. Retrieved August 7, 2018.
  2. Mercer, W., et al. (2020, March 5). Bisonal: 10 years of play. Retrieved January 26, 2022.
  1. Zykov, K. (2020, August 13). CactusPete APT group’s updated Bisonal backdoor. Retrieved May 5, 2021.
  2. Secureworks. (2021, January 1). BRONZE HUNTLEY Threat Profile. Retrieved May 5, 2021.