Analysis by: Clive Fuentebella
ALIASES:

Worm:Win32/Renocide.gen!A (MICROSOFT)

 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

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

This Worm 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: 1,020,956 bytes
File Type: EXE
Memory Resident: Yes
Payload: Connects to URLs/IPs, Drops files

Arrival Details

This Worm 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 Worm drops the following files:

  • {Drive}:\{Random characters}
  • %System%\autorun.inf
  • %System%\csrcs.exe
  • %User Temp%\{Random characters}
  • %User Temp%\{Random characters}.tmp
  • %User Temp%\~ip.tmp
  • %User Temp%\suicide.bat

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.. %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:

  • "%System%\csrcs.exe"
  • cmd /c $User Temp%\suicide.bat
  • ping -n 5 -w 250 127.0.0.1
  • "%System%\rundll32.exe" "%System%\wininet.dll",DispatchAPICall 1

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

Other System Modifications

This Worm adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DRM\amty
regexp = {Number}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DRM\amty
ilop = 1

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DRM\amty
fix =

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DRM\amty
fix1 = 1

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DRM\amty
exp1 = {Random characters}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DRM\amty
dreg = {Random characters}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
Explorer\Run
csrcs = %System%\csrcs.exe

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = 2

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
SuperHidden = 0

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = 0

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = Explorer.exe csrcs.exe (Changed from explorer.exe)

Other Details

This Worm does the following:

  • It connects to the following URL:
    • www.{BLOCKED}myip.com

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 16.800.04
FIRST VSAPI PATTERN DATE: 24 Jun 2021
VSAPI OPR PATTERN File: 16.801.00
VSAPI OPR PATTERN Date: 25 Jun 2021

Step 1

Trend Micro Predictive Machine Learning detects and blocks malware at the first sign of its existence, before it executes on your system. When enabled, your Trend Micro product detects this malware under the following machine learning name:

    • Troj.Win32.TRX.XXPE50FSX011

Step 2

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 3

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 4

Restart in Safe Mode

[ Learn More ]

Step 5

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\DRM\amty
    • regexp={Number}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DRM\amty
    • ilop=1
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DRM\amty
    • fix=
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DRM\amty
    • fix1=1
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DRM\amty
    • exp1={Random characters}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DRM\amty
    • dreg={Random characters}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Explorer\Run
    • csrcs=%System%\csrcs.exe
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • Hidden=2
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • SuperHidden=0
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • ShowSuperHidden=0

Step 6

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\Microsoft\Windows NT\CurrentVersion\Winlogon
    • Shell=Explorer.exe csrcs.exe

Step 7

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.
  • {Drive}:\{Random characters}
  • %System%\autorun.inf
  • %System%\csrcs.exe
  • %User Temp%\{Random characters}
  • %User Temp%\{Random characters}.tmp
  • %User Temp%\~ip.tmp
  • %User Temp%\suicide.bat

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Worm.Win32.AUTORUN.IOF. 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 this Knowledge Base page for more information.


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