ALIASES:

HEUR:Backdoor.Win32.Zegost.gen (Kaspersky)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 REPORTED INFECTION:
 SYSTEM IMPACT RATING:
 INFORMATION EXPOSURE:

  • Threat Type: Potentially Unwanted Application

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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.

  TECHNICAL DETAILS

File Size: 140,864 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 17 Jan 2020

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 processes:

  • taskkill /im chrome.exe /t /f

It creates the following folders:

  • %User Profile%\AppData
  • %Program Files%\Google
  • %System Root%\Users
  • %Program Files%\Google\Chrome
  • %Program Files%\Google\Chrome\Application

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name} on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000(32-bit), Server 2003(32-bit), XP, Vista(64-bit), 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit) , or C:\Program Files (x86) in Windows XP(64-bit), Vista(64-bit), 7(64-bit), 8(64-bit), 8.1(64-bit), 2008(64-bit), 2012(64-bit) and 10(64-bit).. %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)

Other System Modifications

This Potentially Unwanted Application deletes the following folders:

  • %User Temp%\nsg73B9.tmp

(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).)

Dropping Routine

This Potentially Unwanted Application drops the following files:

  • %Program Files%\Google\Chrome\Application\chromeHewlett.exe
  • %System Root%\Users\Public\Desktop\Google Chrome.lnk
  • %Application Data%\Microsoft\Internet Explorer\Quick Launch\User Pinned\TaskBar\Mozilla Firefirefox.lnk
  • %Desktop%\Mozilla firefox.lnk
  • %Program Files%\Google\Chrome\Application\chrome.exe
  • %Start Menu%\Programs\Mozilla firefox.lnk
  • %All Users Profile%\Microsoft\Windows\Start Menu\Programs\Google Chrome.lnk
  • %Program Files%\Google\Chrome\Application\reschedule.exe
  • %All Users Profile%\Microsoft\Windows\Start Menu\Programs\Mozilla firefox.lnk
  • %System Root%\Users\Public\Desktop\firefox.lnk

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000(32-bit), Server 2003(32-bit), XP, Vista(64-bit), 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit) , or C:\Program Files (x86) in Windows XP(64-bit), Vista(64-bit), 7(64-bit), 8(64-bit), 8.1(64-bit), 2008(64-bit), 2012(64-bit) and 10(64-bit).. %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming 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).. %Start Menu% is the current user's Start Menu folder, which is usually C:\Windows\Start Menu or C:\Documents and Settings\{User name}\Start Menu on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %All Users Profile% is the common user's profile folder, which is usually C:\Documents and Settings\All Users on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit). )

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.850

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

Identify and terminate files detected as PUA.Win32.DotDo.USMANIOGAL

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 3

Search and delete these components

[ Learn More ]
There may be some components 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.
  • %Program Files%\Google\Chrome\Application\chromeHewlett.exe
  • %System Root%\Users\Public\Desktop\Google Chrome.lnk
  • %Application Data%\Microsoft\Internet Explorer\Quick Launch\User Pinned\TaskBar\Mozilla Firefirefox.lnk
  • %Desktop%\Mozilla firefox.lnk
  • %Program Files%\Google\Chrome\Application\chrome.exe
  • %Start Menu%\Programs\Mozilla firefox.lnk
  • %All Users Profile%\Microsoft\Windows\Start Menu\Programs\Google Chrome.lnk
  • %Program Files%\Google\Chrome\Application\reschedule.exe
  • %All Users Profile%\Microsoft\Windows\Start Menu\Programs\Mozilla firefox.lnk
  • %System Root%\Users\Public\Desktop\firefox.lnk

Step 4

Search and delete these folders

[ 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 Profile%\AppData
  • %Program Files%\Google
  • %System Root%\Users
  • %Program Files%\Google\Chrome
  • %Program Files%\Google\Chrome\Application

Step 5

Scan your computer with your Trend Micro product to delete files detected as PUA.Win32.DotDo.USMANIOGAL. 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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