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Worm.Win32.DISKWATHER.YYOQ

March 08, 2019
 Analysis by: John Donnie Celestre
 ALIASES:

Trojan.Win32.DLLhijack.ii (KASPERSKY); Win32/Korplug.KM trojan (NOD32)

 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Propagates via email


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. It arrives as a component bundled with malware/grayware packages.

It uses file names similar to those of legitimate applications to trick a user into thinking they are legitimate. It modifies certain registry entries to hide Hidden files. It requires being executed with a specific argument/parameter, an additional component, or in a specific environment in order to proceed with its intended routine.

  TECHNICAL DETAILS

File Size:

7,680 bytes

File Type:

DLL

Memory Resident:

Yes

Initial Samples Received Date:

21 Feb 2019

Payload:

Steals information

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.

It arrives as a component bundled with malware/grayware packages.

Installation

This Worm drops the following component file(s):

  • %All Users Profile%\MyFiles\hypertrm.org
  • %All Users Profile%\MyFiles\timedatestamp
  • %All Users Profile%\MyFiles\aGhmLnRtcA.tmp
  • %All Users Profile%\MyFiles\aHNjLnRtcA.tmp
  • %All Users Profile%\MyFiles\{2 fix characters}{8 random characters}
  • %All Users Profile%\MyFiles\hypertrm.exe ← legitimate .exe file
  • %All Users Profile%\MyFiles\uk1337BA1 ← encrypted file detected as Worm.Win32.DISKWATHER.YYOQ.component

It drops and executes the following files:

  • %AllUsersProfile%\khrmwtr.dll

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

  • %All Users Profile%\MyFiles\HYPERTRM.dll

(Note: %All Users Profile% is the common user's profile folder, which is usually C:\Documents and Settings\All Users on Windows 2000, XP, and Server 2003, or C:\ProgramData on Windows Vista, 7, and 8. )

It adds the following processes:

  • "%All Users Profile%\MyFiles\HYPERTRM.dll",AfxGetHttpRaquestMgr

(Note: %All Users Profile% is the common user's profile folder, which is usually C:\Documents and Settings\All Users on Windows 2000, XP, and Server 2003, or C:\ProgramData on Windows Vista, 7, and 8. )

It adds the following possibly malicious files or file components:

  • filelist.abc
  • sendinfo.abc
  • failed.abc

It creates the following folders:

  • %All Users Profile%\MyFiles

(Note: %All Users Profile% is the common user's profile folder, which is usually C:\Documents and Settings\All Users on Windows 2000, XP, and Server 2003, or C:\ProgramData on Windows Vista, 7, and 8. )

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • UniqueUDiskWather

Other Details

This Worm uses file names similar to those of legitimate applications to trick a user into thinking they are legitimate.

It requires the following additional components to properly run:

  • sendlist.abc

It modifies the following registry entries to hide Hidden files:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = 1

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced\Folder\Hidden\
SHOWALL
CheckedValue = 1

It does the following:

  • It checks if it runs under rundll32.exe
  • It re-executes explorer.exe if hypertrm.exe is found at the foreground window
  • Sends copies of itself using the credentials stored in sendlist.abc via Email and uses the following notable strings:
    • Gmail Mail Server
    • Check your inbox
    • Supernatural! (v1.94) Professional
  • It steals clipboard data.
  • It lists media files found in:
    • C:\Program Files\
    • C:\Program Files (x86)\
    with the following extensions:
    • gif
    • jpg
    • mkv
    • mp3
    • mp4
    • png
    • rmvb
  • Gathered information are possibly sent in one of the emails found in sendlist.abc.
  • It creates an autostart registry using the legitimate file to load the malicous DLL:
    • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
      • hypertrm = %All Users Profile%\MyFiles\hypertrm.exe

(Note: %All Users Profile% is the common user's profile folder, which is usually C:\Documents and Settings\All Users on Windows 2000, XP, and Server 2003, or C:\ProgramData on Windows Vista, 7, and 8. )

It requires being executed with a specific argument/parameter, an additional component, or in a specific environment in order to proceed with its intended routine.

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.858.02

FIRST VSAPI PATTERN DATE:

08 Mar 2019

VSAPI OPR PATTERN File:

14.859.00

VSAPI OPR PATTERN Date:

09 Mar 2019

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 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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • hypertrm = %All Users Profile%\MyFiles\hypertrm.exe

Step 5

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: Hidden = 1
      To: Hidden = {user preference}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\Hidden\SHOWALL
    • From: CheckedValue = 1
      To: CheckedValue = {user preference}

Step 6

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.
  • %All Users Profile%\MyFiles\hypertrm.exe
  • %All Users Profile%\MyFiles\uk1337BA1
  • %All Users Profile%\MyFiles\HYPERTRM.dll
  • %All Users Profile%\MyFiles\hypertrm.org
  • %All Users Profile%\MyFiles\timedatestamp
  • %All Users Profile%\MyFiles\aGhmLnRtcA.tmp
  • %All Users Profile%\MyFiles\aHNjLnRtcA.tmp
  • %All Users Profile%\MyFiles\{2 fix characters}{8 random characters}
  • %AllUsersProfile%\khrmwtr.dll

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Worm.Win32.DISKWATHER.YYOQ. 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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