Worm.Win32.MYDOOM.AC

November 20, 2020
 Analysis by: Paulo Samson
 ALIASES:

Worm:Win32/Mydoom.L@mm (MICROSOFT) ; Email-Worm.Win32.Mydoom.l (KASPERSKY)

 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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:

56,336 bytes

File Type:

EXE

Initial Samples Received Date:

27 Aug 2020

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 copies of itself into the affected system:

  • %Windows%\lsass.exe
  • {Folder Name}\Harry Potter.com
  • {Folder Name}\Harry Potter.exe
  • {Folder Name}\Harry Potter.ShareReactor.com
  • {Folder Name}\ICQ 4 Lite.com
  • {Folder Name}\ICQ 4 Lite.exe
  • {Folder Name}\ICQ 4 Lite.ShareReactor.com
  • {Folder Name}\index.com
  • {Folder Name}\index.exe
  • {Folder Name}\index.ShareReactor.com
  • {Folder Name}\Kazaa Lite.com
  • {Folder Name}\Kazaa Lite.exe
  • {Folder Name}\Kazaa Lite.ShareReactor.com
  • {Folder Name}\Winamp 5.0 (en) Crack.com
  • {Folder Name}\Winamp 5.0 (en) Crack.exe
  • {Folder Name}\Winamp 5.0 (en) Crack.ShareReactor.com
  • {Folder Name}\Winamp 5.0 (en).com
  • {Folder Name}\Winamp 5.0 (en).exe;
  • {Folder Name}\Winamp 5.0 (en).ShareReactor.com
  • {Folder Name}\WinRAR.v.3.2.and.key.com
  • {Folder Name}\WinRAR.v.3.2.and.key.exe
  • {Folder Name}\WinRAR.v.3.2.and.key.ShareReactor.com

It drops the following files:

  • %User Temp%\xp7yiuUgrmq.txt
  • %User Temp%\tmp{4 random alphanumeric characters}.tmp --> deleted afterwards

(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).)

Autostart Technique

This Worm adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Traybar = %Windows%\lsass.exe

Other Details

This Worm adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\POSIX

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\POSIX

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

16.190.04

FIRST VSAPI PATTERN DATE:

27 Aug 2020

VSAPI OPR PATTERN File:

16.191.00

VSAPI OPR PATTERN Date:

28 Aug 2020

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.XXPE50FFF036

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 key

[ 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\CurrentVersion\POSIX
    • "" = ""
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\POSIX
    • "" = ""

Step 6

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\Windows\CurrentVersion\Run
    • Traybar = %Windows%\lsass.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.
  • %Windows%\lsass.exe
  • {Folder Name}\Harry Potter.com
  • {Folder Name}\Harry Potter.exe
  • {Folder Name}\Harry Potter.ShareReactor.com
  • {Folder Name}\ICQ 4 Lite.com
  • {Folder Name}\ICQ 4 Lite.exe
  • {Folder Name}\ICQ 4 Lite.ShareReactor.com
  • {Folder Name}\index.com
  • {Folder Name}\index.exe
  • {Folder Name}\index.ShareReactor.com
  • {Folder Name}\Kazaa Lite.com
  • {Folder Name}\Kazaa Lite.exe
  • {Folder Name}\Kazaa Lite.ShareReactor.com
  • {Folder Name}\Winamp 5.0 (en) Crack.com
  • {Folder Name}\Winamp 5.0 (en) Crack.exe
  • {Folder Name}\Winamp 5.0 (en) Crack.ShareReactor.com
  • {Folder Name}\Winamp 5.0 (en).com
  • {Folder Name}\Winamp 5.0 (en).exe;
  • {Folder Name}\Winamp 5.0 (en).ShareReactor.com
  • {Folder Name}\WinRAR.v.3.2.and.key.com
  • {Folder Name}\WinRAR.v.3.2.and.key.exe
  • {Folder Name}\WinRAR.v.3.2.and.key.ShareReactor.com
  • %User Temp%\xp7yiuUgrmq.txt

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Worm.Win32.MYDOOM.AC. 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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