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PUA.Win32.Installcore.USMANHOBXF

February 27, 2021
 Analysis by: Denisse Camille Layco
 ALIASES:

PUA/InstallCore.Gen7 (ANTIVIR); Downware.InstallCore (VBA32)

 PLATFORM:

Windows

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

  • Threat Type: Potentially Unwanted Application

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware


This Potentially Unwanted Application arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It connects to certain websites to send and receive information. However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

698,144 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

18 Feb 2021

Payload:

Drops files, Connects to URLs/IPs

Arrival Details

This Potentially Unwanted Application 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 Potentially Unwanted Application adds the following folders:

  • %User Temp%\ish{random numbers}
  • %User Temp%\ISH{random numbers}\css
  • %User Temp%\ISH{random numbers}\css\sdk-ui
  • %User Temp%\ISH{random numbers}\css\sdk-ui\images
  • %User Temp%\ISH{random numbers}\images
  • %User Temp%\ISH{random numbers}\locale

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It drops the following files:

  • %User Temp%\{random characters}.log -> deleted afterwards
  • %User Temp%\ish{random numbers}\css\ie6_main.css
  • %User Temp%\ish{random numbers}\css\main.css
  • %User Temp%\ish{random numbers}\css\sdk-ui\browse.css
  • %User Temp%\ish{random numbers}\css\sdk-ui\button.css
  • %User Temp%\ish{random numbers}\css\sdk-ui\checkbox.css
  • %User Temp%\ish{random numbers}\css\sdk-ui\images\button-bg.png
  • %User Temp%\ish{random numbers}\css\sdk-ui\images\progress-bg-corner.png
  • %User Temp%\ish{random numbers}\css\sdk-ui\images\progress-bg.png
  • %User Temp%\ish{random numbers}\css\sdk-ui\images\progress-bg2.png
  • %User Temp%\ish{random numbers}\css\sdk-ui\progress-bar.css
  • %User Temp%\ish{random numbers}\csshover3.htc
  • %User Temp%\ish{random numbers}\form.bmp.Mask
  • %User Temp%\ish{random numbers}\images\BG.jpg
  • %User Temp%\ish{random numbers}\images\close.png
  • %User Temp%\ish{random numbers}\images\close_hover.png
  • %User Temp%\ish{random numbers}\images\Color_Button.png
  • %User Temp%\ish{random numbers}\images\Color_Button_Hover.png
  • %User Temp%\ish{random numbers}\images\default_tb.png
  • %User Temp%\ish{random numbers}\images\default_wi.png
  • %User Temp%\ish{random numbers}\images\Grey_Button.png
  • %User Temp%\ish{random numbers}\images\Grey_Button_Hover.png
  • %User Temp%\ish{random numbers}\images\icon_generic.png
  • %User Temp%\ish{random numbers}\images\loader.gif
  • %User Temp%\ish{random numbers}\images\Pause_Button.png
  • %User Temp%\ish{random numbers}\images\progress.png
  • %User Temp%\ish{random numbers}\images\ProgressBar.png
  • %User Temp%\ish{random numbers}\images\Quick_Specs.png
  • %User Temp%\ish{random numbers}\images\Resume_Button.png
  • %User Temp%\ish{random numbers}\images\sponsored.png
  • %User Temp%\ish{random numbers}\locale\AR.locale
  • %User Temp%\ish{random numbers}\locale\CS.locale
  • %User Temp%\ish{random numbers}\locale\DA.locale
  • %User Temp%\ish{random numbers}\locale\DE.locale
  • %User Temp%\ish{random numbers}\locale\EL.locale
  • %User Temp%\ish{random numbers}\locale\EN.locale
  • %User Temp%\ish{random numbers}\locale\ES.locale
  • %User Temp%\ish{random numbers}\locale\FR.locale
  • %User Temp%\ish{random numbers}\locale\ID.locale
  • %User Temp%\ish{random numbers}\locale\IT.locale
  • %User Temp%\ish{random numbers}\locale\JA.locale
  • %User Temp%\ish{random numbers}\locale\KO.locale
  • %User Temp%\ish{random numbers}\locale\NL.locale
  • %User Temp%\ish{random numbers}\locale\NO.locale
  • %User Temp%\ish{random numbers}\locale\PL.locale
  • %User Temp%\ish{random numbers}\locale\PT.locale
  • %User Temp%\ish{random numbers}\locale\RU.locale
  • %User Temp%\ish{random numbers}\locale\SV.locale
  • %User Temp%\ish{random numbers}\locale\TR.locale
  • %User Temp%\ish{random numbers}\locale\ZH.locale
  • %User Temp%\ish{random numbers}\bootstrap_{random numbers}.html -> deleted afterwards
  • %User Temp%\{random characters}.log -> deleted afterwards
  • %User Temp%\ICReinstall_{malware file name}.exe -> copy of itself
  • %Desktop%\Continue Google Earth Installation.lnk -> shortcut to %User Temp%\ICReinstall_{malware file name}.exe
  • %User Temp%\{random characters}.log -> deleted afterwards
  • %User Temp%\is{random numbers}\{random numbers}_stp.EXE

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Desktop% is the current user's desktop, which is usually C:\Documents and Settings\{User Name}\Desktop on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\Desktop on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It adds the following processes:

  • "{malware file path and name}" /_ShowProgress

Other System Modifications

This Potentially Unwanted Application adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DirectDraw\MostRecentApplication
Name = {malware file name}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DirectDraw\MostRecentApplication
ID = 708992537

Other Details

This Potentially Unwanted Application connects to the following website to send and receive information:

  • http://os.{BLOCKED}iacdn.com/Vittalia/?v={version}&c={random number}
  • http://media.{BLOCKED}tk.com/
  • http://pf.{BLOCKED}t.com/s/2/7/27632-673366-google-earth.exe
  • http://os2.{BLOCKED}iacdn.com/Vittalia/?v={version}&c={random number}
  • http://rp.{BLOCKED}iacdn.com/?pcrc={random number}

It displays the following images:




However, as of this writing, the said sites are inaccessible.

  SOLUTION

Minimum Scan Engine:

9.800

SSAPI PATTERN File:

2.381.00

SSAPI PATTERN Date:

25 Feb 2021

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 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

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\DirectDraw\MostRecentApplication
    • Name = {malware file name}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DirectDraw\MostRecentApplication
    • ID = 708992537

Step 4

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.  
  • %User Temp%\ish{random numbers}\css\ie6_main.css
  • %User Temp%\ish{random numbers}\css\main.css
  • %User Temp%\ish{random numbers}\css\sdk-ui\browse.css
  • %User Temp%\ish{random numbers}\css\sdk-ui\button.css
  • %User Temp%\ish{random numbers}\css\sdk-ui\checkbox.css
  • %User Temp%\ish{random numbers}\css\sdk-ui\images\button-bg.png
  • %User Temp%\ish{random numbers}\css\sdk-ui\images\progress-bg-corner.png
  • %User Temp%\ish{random numbers}\css\sdk-ui\images\progress-bg.png
  • %User Temp%\ish{random numbers}\css\sdk-ui\images\progress-bg2.png
  • %User Temp%\ish{random numbers}\css\sdk-ui\progress-bar.css
  • %User Temp%\ish{random numbers}\csshover3.htc
  • %User Temp%\ish{random numbers}\form.bmp.Mask
  • %User Temp%\ish{random numbers}\images\BG.jpg
  • %User Temp%\ish{random numbers}\images\close.png
  • %User Temp%\ish{random numbers}\images\close_hover.png
  • %User Temp%\ish{random numbers}\images\Color_Button.png
  • %User Temp%\ish{random numbers}\images\Color_Button_Hover.png
  • %User Temp%\ish{random numbers}\images\default_tb.png
  • %User Temp%\ish{random numbers}\images\default_wi.png
  • %User Temp%\ish{random numbers}\images\Grey_Button.png
  • %User Temp%\ish{random numbers}\images\Grey_Button_Hover.png
  • %User Temp%\ish{random numbers}\images\icon_generic.png
  • %User Temp%\ish{random numbers}\images\loader.gif
  • %User Temp%\ish{random numbers}\images\Pause_Button.png
  • %User Temp%\ish{random numbers}\images\progress.png
  • %User Temp%\ish{random numbers}\images\ProgressBar.png
  • %User Temp%\ish{random numbers}\images\Quick_Specs.png
  • %User Temp%\ish{random numbers}\images\Resume_Button.png
  • %User Temp%\ish{random numbers}\images\sponsored.png
  • %User Temp%\ish{random numbers}\locale\AR.locale
  • %User Temp%\ish{random numbers}\locale\CS.locale
  • %User Temp%\ish{random numbers}\locale\DA.locale
  • %User Temp%\ish{random numbers}\locale\DE.locale
  • %User Temp%\ish{random numbers}\locale\EL.locale
  • %User Temp%\ish{random numbers}\locale\EN.locale
  • %User Temp%\ish{random numbers}\locale\ES.locale
  • %User Temp%\ish{random numbers}\locale\FR.locale
  • %User Temp%\ish{random numbers}\locale\ID.locale
  • %User Temp%\ish{random numbers}\locale\IT.locale
  • %User Temp%\ish{random numbers}\locale\JA.locale
  • %User Temp%\ish{random numbers}\locale\KO.locale
  • %User Temp%\ish{random numbers}\locale\NL.locale
  • %User Temp%\ish{random numbers}\locale\NO.locale
  • %User Temp%\ish{random numbers}\locale\PL.locale
  • %User Temp%\ish{random numbers}\locale\PT.locale
  • %User Temp%\ish{random numbers}\locale\RU.locale
  • %User Temp%\ish{random numbers}\locale\SV.locale
  • %User Temp%\ish{random numbers}\locale\TR.locale
  • %User Temp%\ish{random numbers}\locale\ZH.locale
  • %User Temp%\ICReinstall_{malware file name}.exe
  • %Desktop%\Continue Google Earth Installation.lnk
  • %User Temp%\is{random numbers}\{random numbers}_stp.EXE

Step 5

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.
  • %User Temp%\ish{random numbers}
  • %User Temp%\ISH{random numbers}\css
  • %User Temp%\ISH{random numbers}\css\sdk-ui
  • %User Temp%\ISH{random numbers}\css\sdk-ui\images
  • %User Temp%\ISH{random numbers}\images
  • %User Temp%\ISH{random numbers}\locale

Step 6

Scan your computer with your Trend Micro product to delete files detected as PUA.Win32.Installcore.USMANHOBXF. 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 the following Trend Micro Support pages for more information:


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