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Trickbot resurgence with fileless BazarBackdoor

    • Updated:
    • 18 Feb 2021
    • Product/Version:
    • Apex One 2019
    • Deep Discovery Email Inspector All
    • Deep Discovery Inspector All
    • Deep Security 12.0
    • OfficeScan XG
    • ScanMail for Exchange 14.0
    • Worry-Free Business Security Standard 10.0
    • Platform:

Trickbot was first discovered in August, 2016 as a banking trojan which infected computers to steal email passwords and address books to spread malicious emails from compromised email accounts. It has developed new capabilities and techniques to trick users into executing its disguised file, and incorporated new modules in each campaign.

The same group behind Trickbot is believed to develop a new backdoor module called BazarBackdoor due to spam origin, method of operation, and code overlap analysis. Both utilize the same crypter and email chains as previous Trickbot campaigns, as well as the Emercoin DNS resolution service for C&C server communication. The disguised file here is BazarBackdoor, named after its .bazar C&C DNS domains. This is a lightweight malware aimed to evade detection. Once executed, it connects to C&C and downloads its backdoor payload to memory. The backdoor’s goal is to execute binaries, scripts, and modules, kill processes and remove itself from the compromised machine.

As of February 2021, researches about TrickBot's stealthy BazarBackdoor malware have been rewritten in Nim programming language to evade detection by security software.


  • Phishing mail w/ link (customer complaint, COVID-19 payroll report, employee termination list)
  • Connects to C&C domains {word}game.bazar
  • Perform fileless operation: download latest backdoor version and load into memory
  • Backdoor downloads and executes the Cobalt Strike penetration testing and post-exploitation toolkit on the compromised machine
  • Remains undetected by user and gains persistence by creating a Scheduled Task, Run Registry, or a Startup entry


  • Information theft
  • Stealth and fileless operation
  • Backdoor commands
  • Network compromise via Cobalt Strike


  • Compromise system security - with backdoor capabilities that can execute malicious commands
  • Violation of user privacy - gathers user credentials and steals user information

Additional Threat Reference Information

Infection Chain

Sample Spam (Customer Complaint Spam)


Arrives as a customer complaint, employee termination lists, or COVID-19-themed payroll reports spam mailInitial AccessT1193 Spearphishing Attachment
Tricks user to open an executable file disguise as PDF or Word documentExecutionT1204 User Execution
Process Doppelganging into svchost.exeDefense EvasionT1186 Process Doppelganging
Creates scheduled task of the loaderPersistence, Privilege EscalationT1053 Scheduled Task
Creates an autorun value in registry or Startup shortcutPersistenceT1060 Registry Run Keys / Startup Folder
Potential to control the compromised machine or send gathered information to C&C server of attackerExfiltrationT1041 Exfiltration Over Command and Control Channel

Available Solutions

Solution ModulesSolution AvailablePattern BranchRelease DateDetection/Policy/Rules
Email ProtectionYesAS Pattern 5398May 5. 2020-
URL ProtectionYesIn the Cloud--
Advanced Threat Scan Engine (ATSE)Yes15.841.00April  28, 2020-
Predictive Learning (TrendX)YesIn the Cloud-Troj.Win32.TRX.XXPE50FFF035
File detection (VSAPI)YesENT OPR 15.841.00April  28, 2020Trojan.Win32.TRICKBOT.TIGOCBAINS
YesSmart Scan 16.520.00February  5, 2021Trojan.Win64.BAZALOADER.FAIO (NIM Compiled BazarBackdoor)
Network PatternYesNCIP 1.13425.00
NCCP 1.12857.00
August 29, 2018Trickbot DDI rule 2413
Behavioral Monitoring (AEGIS)----
Remove a Malware / Virus
Solution Id:
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