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PUA.Win32.DownloadAssistant.GH

January 22, 2020
 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:

5,385,272 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

22 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:

  • "%User Temp%\is-51GEA.tmp\Sunt.exe" a23dac762cdc339d77ac1996489a2d4a

(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 creates the following folders:

  • %User Temp%\is-51GEA.tmp\_isetup

(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).)

Other System Modifications

This Potentially Unwanted Application adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0000
Owner = "h\x00\x00\xef\xf9\xb7.\xa0b\xd5\x01"

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0000
SessionHash = "{random characters}"

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0000
Sequence = "1"

It deletes the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0000\Sequence

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0000\SessionHash

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0000\Owner

Dropping Routine

This Potentially Unwanted Application drops the following files:

  • %User Temp%\is-51GEA.tmp\_isetup\_shfoldr.dll
  • %User Temp%\is-51GEA.tmp\Sunt.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).)

Other Details

This Potentially Unwanted Application connects to the following possibly malicious URL:

  • http://{BLOCKED}record.live/v2/events

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.DownloadAssistant.GH

[ 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

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_CURRENT_USER\Software\Microsoft\RestartManager\Session0000
    • Owner = "h\x00\x00\xef\xf9\xb7.\xa0b\xd5\x01"
  • In HKEY_CURRENT_USER\Software\Microsoft\RestartManager\Session0000
    • SessionHash = "{random characters}"
  • In HKEY_CURRENT_USER\Software\Microsoft\RestartManager\Session0000
    • Sequence = "1"

Step 4

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.
  • %User Temp%\is-51GEA.tmp\_isetup\_shfoldr.dll
  • %User Temp%\is-51GEA.tmp\Sunt.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%\is-51GEA.tmp\_isetup

Step 6

Scan your computer with your Trend Micro product to delete files detected as PUA.Win32.DownloadAssistant.GH. 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:

Step 7

Restore these deleted registry keys/values from backup

*Note: Only Microsoft-related keys/values will be restored. If the malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

  • In HKEY_CURRENT_USER\Software\Microsoft\RestartManager\Session0000
    • Sequence
  • In HKEY_CURRENT_USER\Software\Microsoft\RestartManager\Session0000
    • SessionHash
  • In HKEY_CURRENT_USER\Software\Microsoft\RestartManager\Session0000
    • Owner


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