Modified by: Augusto II Remillano

ALIASES:

Virus:Win32/Neshta.A (Microsoft), Win32/Neshta.A virus (NOD32), Virus.Win32.Neshta.a (Kaspersky)

 PLATFORM:

Windows

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

  • Threat Type: File infector

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

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

It prepends its codes to target files.

  TECHNICAL DETAILS

File Size: 41,472 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 22 Oct 2018
Payload: Drops files

Arrival Details

This File infector 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 File infector drops the following copies of itself into the affected system:

  • %Windows%\svchost.com

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

  • MutexPolesskayaGlush*.*{\xc2\x90}svchost.com\xc2\x90exefile\shell\open\command\xe2\x80\xb9\xc3\x80 "%1" %*\xc5\x93\xe2\x80\x98@

Other System Modifications

This File infector modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
exefile\shell\open\
command
(Default) = "%Windows%\svchost.com "%1" %*"

File Infection

This File infector infects the following file types:

  • EXE

It prepends its codes to target files.

It avoids infecting files of the following sizes:

  • less than 41,472 bytes or greater than 10,000,000 bytes

It avoids infecting files that contain the following strings in their names:

  • PROGRA~1
  • %Windows%
  • %Temp%

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.. %Temp% is the Windows temporary folder, where it usually is C:\Windows\Temp on all Windows operating system versions.)

Dropping Routine

This File infector drops the following files:

  • %Windows%\directx.sys - contains the full path name of the infected file that was last executed.

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 10.632.03
FIRST VSAPI PATTERN DATE: 27 Feb 2014
VSAPI OPR PATTERN File: 10.633.00
VSAPI OPR PATTERN Date: 28 Feb 2014

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

Restore this modified 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\Classes\exefile\shell\open\command
    • From: (Default) = %Windows%\svchost.com "%1" %*"
      To: (Default) = "%1" %*"

Step 4

Scan your computer with your Trend Micro product to delete files detected as PE_NESHTA.A-O. 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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