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Trojan.INF.HIDDENTEAR.THAOGBA

January 08, 2021
 Analysis by: Thea Patrice Tajonera
 ALIASES:

INF/Agent.J trojan (NOD32)

 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


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 automatically executes files when a user opens a drive.

  TECHNICAL DETAILS

File Size:

583 bytes

File Type:

INF

Memory Resident:

No

Initial Samples Received Date:

07 Jan 2021

Payload:

Executes files

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.

Propagation

The said .INF file contains the following strings:

[version]
Signature=$chicago$
AdvancedINF=2.5

[DefaultInstall]
CustomDestination=CustInstDestSectionAllUsers

RunPreSetupCommands=RunPreSetupCommandsSection

[RunPreSetupCommandsSection]
; Commands Here will be run Before Setup Begins to install
cmd /c start "C:\Windows\temp\{Random Characters}.exe"
taskkill /IM cmstp.exe /F

[CustInstDestSectionAllUsers]
49000,49001=AllUSer_LDIDSection, 7

[AllUSer_LDIDSection]
"HKLM", "SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths\CMMGR32.EXE", "ProfileInstallPath", "%UnexpectedError%", ""

[Strings]
ServiceName="Crimson"
ShortSvcName="Crimson"

Other Details

This Trojan automatically executes the following files when a user opens a drive:

  • C:\Windows\temp\{Random Characters}.exe
  • taskkill /IM cmstp.exe /F

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

16.462.06

FIRST VSAPI PATTERN DATE:

07 Jan 2021

VSAPI OPR PATTERN File:

16.463.00

VSAPI OPR PATTERN Date:

08 Jan 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

Search and delete AUTORUN.INF files created by Trojan.INF.HIDDENTEAR.THAOGBA that contain these strings

[ Learn More ]
  • [version]
    Signature=$chicago$
    AdvancedINF=2.5

    [DefaultInstall]
    CustomDestination=CustInstDestSectionAllUsers
    RunPreSetupCommands=RunPreSetupCommandsSection

    [RunPreSetupCommandsSection]
    ; Commands Here will be run Before Setup Begins to install
    cmd /c start "C:\Windows\temp\{Random Characters}.exe"
    taskkill /IM cmstp.exe /F

    [CustInstDestSectionAllUsers]
    49000,49001=AllUSer_LDIDSection, 7

    [AllUSer_LDIDSection]
    "HKLM", "SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths\CMMGR32.EXE", "ProfileInstallPath", "%UnexpectedError%", ""

    [Strings]
    ServiceName="Crimson"
    ShortSvcName="Crimson"

Step 3

Scan your computer with your Trend Micro product to delete files detected as Trojan.INF.HIDDENTEAR.THAOGBA. 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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