Author: John Rey Canon   

 

W97M.Downloader (Symantec); W97M.Downloader.HNT (F-Secure)

 PLATFORM:

Windows

 OVER ALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE
Low
Medium
High
Critical

  • Threat Type:
    Trojan

  • Destructiveness:
    No

  • Encrypted:
    Yes

  • In the wild:
    Yes

  OVERVIEW

INFECTION CHANNEL: Downloaded from the Internet

This malware is dropped as a .DLL file. It has delivery mechanisms that are strikingly similar to threat actor group known as MuddyWater. Based on our analysis, we can confirm that the targets were Turkish government organizations related to the finance and energy sectors.

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.

  TECHNICAL DETAILS

File size: 1,167,872 bytes
File type: DOC
Memory resident: Yes
INITIAL SAMPLES RECEIVED DATE: 23 November 2018

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.

Installation

This Trojan drops the following files:

It adds the following processes:

  • "%System%\cmd.exe" /k %windir%\System32\reg.exe IMPORT %Temp%\B.reg

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

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
w = rundll32 %Temp%\png.dll,RunPow

  SOLUTION

Minimum scan engine: 9.850
First VSAPI Pattern File: 14.644.08
First VSAPI Pattern Release Date: 23 November 2018
VSAPI OPR PATTERN-VERSION: 14.645.00
VSAPI OPR PATTERN DATE: 24 November 2018

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 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

Restart in Safe Mode

[ learnMore ]

Step 4

Delete this registry value

[ learnMore ]

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\Microsoft\Windows\CurrentVersion\Run
    • w = rundll32 %Temp%\png.dll,RunPow

Step 5

Search and delete this file

[ learnMore ]
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.  
  • %Temp%\B.reg
  • %Temp%\png.dll

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Trojan.W97M.POWRUN.AA. 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 this Knowledge Base page for more information.


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