TROJ_DARKNEURON.B

 Analysis by: Cris Nowell Pantanilla

 PLATFORM:

Windows

 OVERALL RISK RATING:
 REPORTED INFECTION:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

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:

98,816 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

25 May 2017

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:

  • {malware path}\System.Web.Helpers.dll
  • %System%\w3wpdiag.exe
  • %System%\System.Web.Helpers.dll
  • %System%\InstallUtil.InstallLog
  • %System%\w3wpdiag.InstallLog
  • %System%\w3wpdiag.InstallState

(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 as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\W3WPDIAG

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\W3WPDIAG
Type = 10

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\W3WPDIAG
Start = 2

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\W3WPDIAG
ErrorControl = 1

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\W3WPDIAG
ImagePath = "%System%\w3wpdiag.exe"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\W3WPDIAG
DisplayName = "Microsoft IIS Diagnostics Service"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\W3WPDIAG
ObjectName = "LocalSystem"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\W3WPDIAG
Description = "Host service for the Microsoft IIS management provider. If this service is stopped or disabled, Microsoft IIS cannot be managed."

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\W3WPDIAG
DelayedAutostart = 0

Other Details

This Trojan does the following:

  • It executes the following command lines:
    • cmd.exe /c w3wpdiag.exe -install
    • cmd.exe /c del *.InstallLog *.InstallState

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.428.06

FIRST VSAPI PATTERN DATE:

25 May 2017

VSAPI OPR PATTERN File:

13.427.00

VSAPI OPR PATTERN Date:

26 May 2017

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

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\CurrentControlSet\services
    • W3WPDIAG

Step 3

Search and delete this file

[ 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.
{malware path}\System.Web.Helpers.dll
%System%\w3wpdiag.exe
%System%\System.Web.Helpers.dll
%System%\InstallUtil.InstallLog
%System%\w3wpdiag.InstallLog
%System%\w3wpdiag.InstallState

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_DARKNEURON.B. 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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