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WORM_ROTINOM.HL

October 19, 2016
 Analysis by: Ryan Gardo
 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:

Downloaded from the Internet, , Propagates via flashdrives


This worm arrives by connecting affected removable drives to a system. It may be unknowingly downloaded by a user while visiting malicious websites.

It uses the default Windows folder icon to trick users into opening the file. Double-clicking the file executes this malware.

It modifies registry entries to hide files with System and Read-only attributes.

  TECHNICAL DETAILS

File Size:

243976 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

17 Oct 2016

Payload:

Modifies system registry, Creates files

Arrival Details

This worm arrives by connecting affected removable drives to a system.

It may be unknowingly downloaded by a user while visiting malicious websites.

Installation

This worm adds the following folders:

  • %Application Data%\Start
  • {Malware Path}\{Malware Filename}
  • %AppDataLocal%\S-1-5-31-1286970278978-5713669491-166975984-320
  • %AppDataLocal%\S-1-5-31-1286970278978-5713669491-166975984-320\dmc
  • %AppDataLocal%\S-1-5-31-1286970278978-5713669491-166975984-320\tlsr
  • %AppDataLocal%\S-1-5-31-1286970278978-5713669491-166975984-320\Rotinom
  • {Removable Drive Letter}\Usb 2.0 Driver
  • {Removable Drive Letter}\Usb 2.0 Driver\S-1-5-31-1286970278978-5713669491-166975984-320
  • {Removable Drive Letter}\Usb 2.0 Driver\S-1-5-31-1286970278978-5713669491-166975984-320\dmc
  • {Removable Drive Letter}\Usb 2.0 Driver\S-1-5-31-1286970278978-5713669491-166975984-320\tlsr

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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.. %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local 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.)

It drops the following copies of itself into the affected system:

  • %AppDataLocal%\Start\update.exe

(Note: %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local 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.)

It uses the default Windows folder icon to trick users into opening the file. Double-clicking the file executes this malware.

Other System Modifications

This worm modifies the following registry key(s)/entry(ies) as part of its installation routine:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Shell Folders
Startup = "%AppDataLocal%\start"

(Note: The default value data of the said registry entry is "%User Profile%\Start Menu\Programs\Startup".)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
User Shell Folders
Startup = "%AppDataLocal%\start"

(Note: The default value data of the said registry entry is "%User Profile%\Start Menu\Programs\Startup".)

It modifies the following registry entries to hide files with System and Read-only attributes:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = 2

(Note: The default value data of the said registry entry is 1.)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
HideFileExt = 1

(Note: The default value data of the said registry entry is 0.)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = 0

(Note: The default value data of the said registry entry is 1.)

Other Details

This worm does the following:

  • It creates copies of itself in removable drives, using names of existing folders in the root directory of the drive as its filename, and then sets the original folder to hidden.
  • This worm copies the contents of the removable drives in the following created folder:
    • %AppDataLocal%\S-1-5-31-1286970278978-5713669491-166975984-320\Rotinom

(Note: %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local 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.)

NOTES:

It opens the following created folder:

  • {Malware Path}\{Malware Filename}

    •   SOLUTION

    Minimum Scan Engine:

    9.800

    VSAPI OPR PATTERN File:

    12.842.02

    VSAPI OPR PATTERN Date:

    17 Oct 2016

    OPP PATTERN File:

    12.843.00

    OPP PATTERN Date:

    17 Nov 2016

    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

    Terminate a process file/s detected as WORM_ROTINOM.HL

    [ Learn More ]

    *Note: If the detected file/s is/are not displayed in theWindows Task Manager, continue doing the next steps.

    Step 5

    Restore this modified 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\Microsoft\Windows\CurrentVersion\Explorer\Advanced
      • From: Hidden = 2
        To: 1
    • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
      • From: HideFileExt = 1
        To: 0
    • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
      • From: ShowSuperHidden = 0
        To: 1
    • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders
      • From: Startup = %User Profile%\Local Settings\Application Data\start
        To: %User Profile%\Start Menu\Programs\Startup
    • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders
      • From: Startup = %User Profile%\Local Settings\Application Data\start
        To: %User Profile%\Start Menu\Programs\Startup

    Step 6

    Search and delete this folder

    [ Learn More ]
    Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
    • %Application Data%\Start
    • {Malware Path}\{Malware Filename}
    • %AppDataLocal%\S-1-5-31-1286970278978-5713669491-166975984-320
    • {Removable Drive Letter}\Usb 2.0 Driver

    Step 7

    Scan your computer with your Trend Micro product to delete files detected as WORM_ROTINOM.HL. 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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