TrickBot Trojan Latest Variant Resilient to Disable Windows Defender

TrickBot Trojan Latest Variant Resilient to Disable Windows Defender

TrickBot is a banking Trojan that has been around since 2016. The threat it poses is quite disastrous as it is designed to steal online banking and other credentials, cryptocurrency wallets, browser information.

The Trojan has a new variant that is currently circling the web, which again attempts to disable Windows Defender on affected systems as seen in previous versions. However, the latest variant of TrickBot has added new methods to ensure that the security program is disabled.

The new variant was discovered by MalwareHunterTeam and Vitali Kremez, and the security researchers succeeded in reverse-engineering its code.

Threat Summary

TypeBanking Trojan
Short DescriptionThe TrickBot Trojan has a new variant which attempts to disable Windows Defender on compromised systems.
Distribution MethodThe TrickBot banking Trojan is mostly distributed in malicious spam campaigns. It’s also known to leverage the EternalBlue exploit (MS17-010) as a distribution technique.
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User ExperienceJoin Our Forum to Discuss TrickBot.

TrickBot Trojan – Technical Details

Upon execution, TrickBot Trojan will start a loader to prepare the system by disabling Windows services and processes that belong to security programs. Then, the Trojan will elevate its privileges, and will load its core component by injecting a DLL. This DLL downloads other modules deployed for credentials and information theft. It also contains the layer needed for communication with its command and control server.

Related: Trickbot Banking Trojan August 2018 Updated with Stealth Code Injection

In August 2018, a stealth code injection was introduced to TrickBot’s code. It will sleep the infection for 30 seconds. This is a technique that can evade signature scans used by security software such as anti-virus solutions, sandbox environments and virtual machine hosts. Their real-time engines can be bypassed or entirely removed by the malicious code.

The actual decryption of the obfuscated Trickbot Trojan is run after the stealth protection code has complete. The 2018 version of the malware uses direct system calls which is similar to Flokibot, a variant of Zeus. This shows that the hackers behind the new Trickbot banking Trojan might have used several different code sources.

The latest variant of the banking Trojan has added the following methods to ensure that Windows Defender and Windows Defender and Microsoft Defender APT are disabled, as reported by Bleeping Computer. It should be noted that these methods are blocked by TamperProtection if it is enabled:

Add policies to SOFTWARE\Policies\Microsoft\Windows Defender\Real-Time Protection for the following:
DisableBehaviorMonitoring: Disables behavior monitoring in Windows Defender.
DisableOnAccessProtection: Disables scanning when you open a program or file.
DisableScanOnRealtimeEnable: Disabled process scanning.
Configures the following Windows Defender preferences via PowerShell:
-DisableRealtimeMonitoring: Disables real time scanning.
-DisableBehaviorMonitoring: Same as above, except as a Windows Defender preference.
-DisableBlockAtFirstSeen: Disables Defender’s Cloud Protection feature.
-DisableIOAVProtection: Disables scans of downloaded files and attachments.
-DisablePrivacyMode: Disables privacy mode so all users can see threat history.
-DisableIntrusionPreventionSystem: Disables network protection for known vulnerability exploits.
-DisableScriptScanning: Disables the scanning of scripts.
-SevereThreatDefaultAction: Set the value to 6, which turns off automatic remediation for severe threats.
-LowThreatDefaultAction: Set the value to 6, which turns off automatic remediation for low threats.
-ModerateThreatDefaultAction: Set the value to 6, which turns off automatic remediation for moderate threats.

When the Trojan detects security software on the compromised system, it is set to configure a debugger via the Image File Execution Options Registry key. Through this action the debugger will launch prior to the program that is executed. In case the debugger is not found, the program will not be able to launch, the researchers explained.


Milena Dimitrova

An inspired writer and content manager who has been with SensorsTechForum for 4 years. Enjoys ‘Mr. Robot’ and fears ‘1984’. Focused on user privacy and malware development, she strongly believes in a world where cybersecurity plays a central role. If common sense makes no sense, she will be there to take notes. Those notes may later turn into articles! Follow Milena @Milenyim

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