Analysis Report

MAR-10445155-1.v1 Truebot Activity Infects U.S. and Canada Based Networks

Release Date
Alert Code


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This document is marked TLP:CLEAR--Recipients may share this information without restriction. Sources may use TLP:CLEAR when information carries minimal or no foreseeable risk of misuse, in accordance with applicable rules and procedures for public release. Subject to standard copyright rules, TLP:CLEAR information may be shared without restriction. For more information on the Traffic Light Protocol (TLP), see



CISA received one Windows Portable Executable (PE) file for analysis. The file is a variant of TrueBot malware. It is designed to collect system information and report it to a command-and-control (C2). The bot is also capable of downloading and executing additional payloads.

For more information about this compromise, see Joint Cybersecurity Advisory Increased Truebot Activity Infects U.S. and Canada Based Networks.

Download the PDF version of this report:

For a downloadable copy of IOCs, see

AA23-187A STIX XML (XML, 204.54 KB )

For a downloadable copy of IOCs associated with this MAR in JSON format, see

MAR-10445155-1.v1 STIX JSON (JSON, 16.51 KB )
Submitted Files (1)

7d75244449fb5c25d8f196a43a6eb9e453652b2185392376e7d44c21bd8431e7 (3LXJyAv6Gf.exe)

Domains (2)







Name 3LXJyAv6Gf.exe
Size 1200732656 bytes
Type PE32+ executable (GUI) x86-64, for MS Windows
MD5 5588286a702e0c36c8318be0b164fa8c
SHA1 5449f3f141958de2d1140bc8323f5ac95c203287
SHA256 7d75244449fb5c25d8f196a43a6eb9e453652b2185392376e7d44c21bd8431e7
SHA512 105e72e1f1e3af8942e0e77e1294f74cd0518f7d601e4e2f20f7ed9db3cd1c67739c31e085e028eafe0394af74b2fbeb6ffbffb67d7731023a04c53a6784924e
ssdeep 25165824:d1AuQ/FFyK8db8kdjeyPpiMh5gbiwcfYjh+dkfaeLq4H/LLhtf:Q/FoK8rteknh54ZcfvdkfpnLhtf
Entropy 7.999996
ESET a variant of Win64/Agent.BVF trojan
YARA Rules
  • rule CISA_10445155_01 : TRUEBOT downloader



           Author = "CISA Code & Media Analysis"

           Incident = "10445155"

           Date = "2023-05-17"

           Last_Modified = "20230523_1500"

           Actor = "n/a"

           Family = "TRUEBOT"

           Capabilities = "n/a"

           Malware_Type = "downloader"

           Tool_Type = "n/a"

           Description = "Detects TRUEBOT downloader samples"

           SHA256 = "7d75244449fb5c25d8f196a43a6eb9e453652b2185392376e7d44c21bd8431e7"


           $s1 = { 64 72 65 6d 6d 66 79 74 74 72 72 65 64 2e 63 6f 6d }

           $s2 = { 4e 73 75 32 4f 64 69 77 6f 64 4f 73 32 }

           $s3 = { 59 69 50 75 6d 79 62 6f 73 61 57 69 57 65 78 79 }

           $s4 = { 72 65 70 6f 74 73 5f 65 72 72 6f 72 2e 74 78 74 }

           $s5 = { 4c 6b 6a 64 73 6c 66 6a 33 32 6f 69 6a 72 66 65 77 67 77 2e 6d 70 34 }

           $s6 = { 54 00 72 00 69 00 67 00 67 00 65 00 72 00 31 00 32 }

           $s7 = { 54 00 55 00 72 00 66 00 57 00 65 00 73 00 54 00 69 00 66 00 73 00 66 }


           5 of them

ssdeep Matches

No matches found.

7d75244449... Connected_To dremmfyttrred[.]com
7d75244449... Connected_To droogggdhfhf[.]com

This artifact is a variant of the TrueBot downloader. The file is padded with over one gigabyte (Gb) of junk code, designed to hinder analysis. When the bot is executed on the system, it will check the current Operating System (OS) version (RtlGetVersion) and the processor architecture (GetNativeSystemInfo). From this information the bot will create a unique ID for the compromised system. It will store the ID in C:\ProgramData as a randomly named 13 character file with a .JSONIP extension, e.g. ‘IgtyXEQuCEvAM.JSONIP’.

The malware proceeds to enumerate all running processes on the system. The bot configuration contains a list of common Windows processes that are excluded from its list. The remaining process names are concatenated into a base64 encoded string. The malware specifically looks for the presence of the following disassembly and debugging tools:

—Begin Disassembly & Debugging Tools—


Process Monitor


Process Explorer

CFF Explorer

Resource Hacker






Zeta Debugger

Rock Debugger

Obsidian debugger

—End Disassembly & Debugging Tools—

The presence of these tools does not change the execution of the malware. They are also concatenated into a base64 encoded string and sent along with the system information.

Next, the malware will collect the ComputerName and Domain name of the system. All of the collected information and the unique ID is sent to a hard-coded Uniform Resource Locator (URL) in a POST request using a unique User-agent string:

—Begin POST Request—



Content-type: application/x-www-form-urlencoded

Mozilla/112.0 (compatible; MSIE 11.0; Windows NT 10.00)

—End POST Request—

The malware uses a second obfuscated domain to accept commands and receive additional payloads. The configuration contains two base64 encoded strings that the malware will decode and run through a string operation to generate a unique hexadecimal string. The hexadecimal string is decoded using the embedded RC4 key ‘YiPumybosaWiWexy’. The following URL was decoded from the strings:

—Begin Decoded URL—


—End Decoded URL—




HTTP Sessions
  • POST


    Content-type: application/x-www-form-urlencoded

    Mozilla/112.0 (compatible; MSIE 11.0; Windows NT 10.00)
dremmfyttrred[.]com Connected_From 7d75244449fb5c25d8f196a43a6eb9e453652b2185392376e7d44c21bd8431e7

3LXJyA6Gf.exe attempts to send the collected system information to this domain.




droogggdhfhf[.]com Connected_From 7d75244449fb5c25d8f196a43a6eb9e453652b2185392376e7d44c21bd8431e7

3LXJyA6Gf.exe receives commands and payloads from this domain.

Relationship Summary

7d75244449... Connected_To dremmfyttrred[.]com
7d75244449... Connected_To droogggdhfhf[.]com
dremmfyttrred[.]com Connected_From 7d75244449fb5c25d8f196a43a6eb9e453652b2185392376e7d44c21bd8431e7
droogggdhfhf[.]com Connected_From 7d75244449fb5c25d8f196a43a6eb9e453652b2185392376e7d44c21bd8431e7


CISA recommends that users and administrators consider using the following best practices to strengthen the security posture of their organization's systems. Any configuration changes should be reviewed by system owners and administrators prior to implementation to avoid unwanted impacts.

  • Maintain up-to-date antivirus signatures and engines.
  • Keep operating system patches up-to-date.
  • Disable File and Printer sharing services. If these services are required, use strong passwords or Active Directory authentication.
  • Restrict users' ability (permissions) to install and run unwanted software applications. Do not add users to the local administrators group unless required.
  • Enforce a strong password policy and implement regular password changes.
  • Exercise caution when opening e-mail attachments even if the attachment is expected and the sender appears to be known.
  • Enable a personal firewall on agency workstations, configured to deny unsolicited connection requests.
  • Disable unnecessary services on agency workstations and servers.
  • Scan for and remove suspicious e-mail attachments; ensure the scanned attachment is its "true file type" (i.e., the extension matches the file header).
  • Monitor users' web browsing habits; restrict access to sites with unfavorable content.
  • Exercise caution when using removable media (e.g., USB thumb drives, external drives, CDs, etc.).
  • Scan all software downloaded from the Internet prior to executing.
  • Maintain situational awareness of the latest threats and implement appropriate Access Control Lists (ACLs).

Additional information on malware incident prevention and handling can be found in National Institute of Standards and Technology (NIST) Special Publication 800-83, "Guide to Malware Incident Prevention & Handling for Desktops and Laptops".

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