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Trojan.BAT.STARTER.UWAOOABQ

October 30, 2021
 Analysis by: Maria Emreen Viray
 ALIASES:

Trojan.BAT.Starter.nz (KASPERSKY)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites. It may be dropped by other malware.

  TECHNICAL DETAILS

File Size:

768 bytes

File Type:

BAT

Memory Resident:

No

Initial Samples Received Date:

22 Oct 2021

Payload:

Modifies system registry, Others

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It may be dropped by the following malware:

Installation

This Trojan adds the following processes:

  • reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Svchost" /v "EntAppsvc" /t REG_MULTI_SZ /d "EntAppsvc" /f
  • sc create "EntAppsvc" binPath= "C:\Windows\system32\svchost.exe -k EntAppsvc" type= share start= auto error= ignore DisplayName= "EntAppsvc"
  • sc description "EntAppsvc" ""
  • reg add "HKLM\SYSTEM\CurrentControlSet\Services\EntAppsvc\Parameters" /f
  • reg add "HKLM\SYSTEM\CurrentControlSet\Services\EntAppsvc\Parameters" /v "ServiceDll" /t REG_EXPAND_SZ /d "%System%\EntAppsvc.dll" /f
  • net start "EntAppsvc"

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

Autostart Technique

This Trojan registers its dropped component as a system service to ensure its automatic execution at every system startup. It does this by creating the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Svchost
EntAppsvc = EntAppsvc

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\EntAppsvc\Parameters
ServiceDll = %System%\EntAppsvc.dll

It registers its dropped component as a system service to ensure its automatic execution at every system startup. It does this by creating the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\EntAppsvc

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\EntAppsvc\Parameters

It starts the following services:

  • EntAppsvc

Other Details

This Trojan does the following:

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

17.152.03

FIRST VSAPI PATTERN DATE:

25 Oct 2021

VSAPI OPR PATTERN File:

17.153.00

VSAPI OPR PATTERN Date:

26 Oct 2021

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.

Step 2

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

 
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Svchost
    • EntAppsvc = EntAppsvc
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\services\EntAppsvc\Parameters
    • ServiceDll = %System%\EntAppsvc.dll

Step 4

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\services\EntAppsvc

Step 5

Scan your computer with your Trend Micro product to delete files detected as Trojan.BAT.STARTER.UWAOOABQ. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check the following Trend Micro Support pages for more information:


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