Analysis by: Paul Steven Nadera

ALIASES:

PUA/InstallCo.zkc (ANTIVIR); PUP/Multitoolbar (Panda)

 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

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.

As of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size: 2,360,552 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 18 May 2021
Payload: Connects to URLs/IPs, Displays windows

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%\in{random string}\css\helpers
  • %User Temp%\in{random string}\css\sdk-ui
  • %User Temp%\in{random string}\css
  • %User Temp%\in{random string}\images
  • %User Temp%\in{random string}\libs
  • %User Temp%\in{random string}\locale
  • %User Temp%\in{random string}

(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%\in{random string}\css\helpers\_align.scss
  • %User Temp%\in{random string}\css\helpers\_backgrounds.scss
  • %User Temp%\in{random string}\css\helpers\_border-radius.scss
  • %User Temp%\in{random string}\css\helpers\_border.scss
  • %User Temp%\in{random string}\css\helpers\_clearfix.scss
  • %User Temp%\in{random string}\css\helpers\_colors.scss
  • %User Temp%\in{random string}\css\helpers\_display.scss
  • %User Temp%\in{random string}\css\helpers\_float.scss
  • %User Temp%\in{random string}\css\helpers\_lists.scss
  • %User Temp%\in{random string}\css\helpers\_margin.scss
  • %User Temp%\in{random string}\css\helpers\_padding.scss
  • %User Temp%\in{random string}\css\helpers\_positions.scss
  • %User Temp%\in{random string}\css\helpers\_typography.scss
  • %User Temp%\in{random string}\css\helpers\_visibility.scss
  • %User Temp%\in{random string}\css\helpers\_width-height.scss
  • %User Temp%\in{random string}\css\helpers\_z-index.scss
  • %User Temp%\in{random string}\css\ie6_main.css
  • %User Temp%\in{random string}\css\ie6_main.scss
  • %User Temp%\in{random string}\css\main.css
  • %User Temp%\in{random string}\css\main.scss
  • %User Temp%\in{random string}\css\sdk-ui\images\button-bg.png
  • %User Temp%\in{random string}\css\sdk-ui\images\progress-bg-corner.png
  • %User Temp%\in{random string}\css\sdk-ui\images\progress-bg.png
  • %User Temp%\in{random string}\css\sdk-ui\images\progress-bg2.png
  • %User Temp%\in{random string}\css\sdk-ui\images
  • %User Temp%\in{random string}\css\sdk-ui\_browse.scss
  • %User Temp%\in{random string}\css\sdk-ui\_button.scss
  • %User Temp%\in{random string}\css\sdk-ui\_checkbox.scss
  • %User Temp%\in{random string}\css\sdk-ui\_progress-bar.scss
  • %User Temp%\in{random string}\css\swAgent.css
  • %User Temp%\in{random string}\css\_functions.scss
  • %User Temp%\in{random string}\css\_helpers.scss
  • %User Temp%\in{random string}\css\_variables.scss
  • %User Temp%\in{random string}\csshover3.htc
  • %User Temp%\in{random string}\form.bmp.Mask
  • %User Temp%\in{random string}\images\BG.png
  • %User Temp%\in{random string}\images\Close.png
  • %User Temp%\in{random string}\images\Close_Hover.png
  • %User Temp%\in{random string}\images\Color_Button.png
  • %User Temp%\in{random string}\images\Color_Button_Hover.png
  • %User Temp%\in{random string}\images\Grey_Button.png
  • %User Temp%\in{random string}\images\Grey_Button_Hover.png
  • %User Temp%\in{random string}\images\Icon_Generic.png
  • %User Temp%\in{random string}\images\Loader.gif
  • %User Temp%\in{random string}\images\Pause_Button.png
  • %User Temp%\in{random string}\images\Progress.png
  • %User Temp%\in{random string}\images\ProgressBar.png
  • %User Temp%\in{random string}\images\Quick_Specs.png
  • %User Temp%\in{random string}\images\Resume_Button.png
  • %User Temp%\in{random string}\images\sponsored.png
  • %User Temp%\in{random string}\libs\localAssests\icc\icc_v5_8.cis
  • %User Temp%\in{random string}\libs\localAssests\icc
  • %User Temp%\in{random string}\libs\localAssests\icut\icut_v2_2.cis
  • %User Temp%\in{random string}\libs\localAssests\icut
  • %User Temp%\in{random string}\libs\localAssests
  • %User Temp%\in{random string}\locale\DE.locale
  • %User Temp%\in{random string}\locale\EN.locale
  • %User Temp%\in{random string}\locale\FR.locale
  • %User Temp%\in{random string}\locale\JA.locale
  • %User Temp%\in{random string}\locale\ZH.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 adds the following processes:

  • "{PUA path}\{PUA filename}.exe" /_ShowProgress /mnl

Download Routine

This Potentially Unwanted Application accesses the following websites to download files:

  • http://www.{BLOCKED}nof.com/

As of this writing, the said sites are inaccessible.

Other Details

This Potentially Unwanted Application does the following:

  • It displays the following progress bar while downloading and installing the software:

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 2.411.00
FIRST VSAPI PATTERN DATE: 27 May 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

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.

Step 4

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%\in{random string}\css\helpers
  • %User Temp%\in{random string}\css\sdk-ui
  • %User Temp%\in{random string}\css
  • %User Temp%\in{random string}\images
  • %User Temp%\in{random string}\libs
  • %User Temp%\in{random string}\locale
  • %User Temp%\in{random string}

Step 5

Scan your computer with your Trend Micro product to delete files detected as PUA.Win32.InstallCore.MANHOBWG. 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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