Analysis by: Michael Jhon Ofiaza


W97M.Downloader (Norton)




  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes


Infection Channel: Downloaded from the Internet, Dropped by other malware

This malware is a downloader used by the OceanLotus threat actor group.

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.


File Size: 958,241 bytes
Memory Resident: No
Initial Samples Received Date: 05 Mar 2019
Payload: Drops 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.


This Trojan drops the following files:

  • %ProgramData%\SecurityAndMaintenance_Error.png (32-bit dll detected as Trojan.Win32.COMETER.AE)
  • %ProgramData%\SecurityAndMaintenance_Error.png (64-bit dll detected as Trojan.Win64.COMETER.AE)
  • %Application Data%\main_background.png (32-bit dll detected as Trojan.Win32.COMETER.AE)
  • %Application Data%\main_background.png (64-bit dll detected as Trojan.Win64.COMETER.AE)

(Note: %ProgramData% is a version of the Program Files folder where any user on a multi-user computer can make changes to programs. This contains application data for all users. This is usually C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit), or C:\Documents and Settings\All Users on Windows Server 2003(32-bit), 2000(32-bit) and XP.. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It adds the following processes:

  • Adds the following process if the system is 64-bit:
    • cmd.exe /S /C reg add HKEY_CURRENT_USER\Software\Classes\CLSID\ /f /reg:64"
    • cmd.exe /S /C reg add HKEY_CURRENT_USER\Software\Classes\CLSID\{2DEA658F-54C1-4227-AF9B-260AB5FC3543} /f /reg:64"
    • cmd.exe /S /C reg add HKEY_CURRENT_USER\Software\Classes\CLSID\{2DEA658F-54C1-4227-AF9B-260AB5FC3543}\InprocServer32 /ve /t REG_SZ /d " & {Malware Location} & " /f /reg:64"

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

{Default} = {Malware Path}


Minimum Scan Engine: 9.850
VSAPI OPR PATTERN File: 14.853.00
VSAPI OPR PATTERN Date: 06 Mar 2019

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_CURRENT_USER\Software\Classes\CLSID\{2DEA658F-54C1-4227-AF9B-260AB5FC3543}\InprocServer32
    • {Default} = {Malware Path}

Step 4

Search and delete these files

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.  
  • %ProgramData%\SecurityAndMaintenance_Error.png
  • %Application Data%\main_background.png

Step 5

Scan your computer with your Trend Micro product to delete files detected as Trojan.W97M.KERRDOWN.A. 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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