Analysis by: John Anthony Banes
ALIASES:

DDoS:Win32/Nitol (Microsoft); Mal/Nitol-C, Mal/Emogen-Y, Mal/Nitol-C (Sophos Lite)

 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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

This Worm 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: 46,592 bytes
File Type: DLL
Memory Resident: No
Initial Samples Received Date: 13 Jul 2018
Payload: Drops files

Arrival Details

This Worm 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 Worm drops and executes the following files:

  • %User Temp%\hrl{random}.tmp
  • %System%\{random}.exe

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

Autostart Technique

This Worm 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\SYSTEM\CurrentControlSet\
Services\Distribu{random}
ImagePath = %System%\{random}.exe

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Distribu{random}
DisplayName = Distribu{random} Transaction Coordinator Service

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Distribu{random}
Description = Distribu{random} Transaction Coordinator Service.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Distribu{random}
ObjectName = LocalSystem

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Distribu{random}\Security
Security = {hex values}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Distribu{random}
ErrorControl = 0

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Distribu{random}
Start = 2

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Distribu{random}
Type = 16

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Distribu{random}\Enum
0 = Root\LEGACY_DISTRIBU{random}\0000

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Distribu{random}\Enum
Count = 1

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Distribu{random}\Enum
NextInstance = 1

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\CurrentControlSet\
Services\Distribu{random}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Distribu{random}\Security

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Distribu{random}\Enum

Other Details

This Worm does the following:

  • This worm drops the following copy of itself in all folders in all physical and removable drives containing an EXE file:
    • lpk.dll

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 14.376.04
FIRST VSAPI PATTERN DATE: 13 Jul 2018
VSAPI OPR PATTERN File: 14.377.00
VSAPI OPR PATTERN Date: 14 Jul 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

[ Learn More ]

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.

 
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • Distribu{random}

Step 5

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.
  • %User Temp%\hrl{random}.tmp
  • %System%\{random}.exe

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_NITOL.DUKP. 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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