Analysis by: Pearl Charlaine Espejo

ALIASES:

Trojan.Ransom.Nuke.1 (Arcabit); Gen:Variant.Ransom.Nuke.1 (F-Secure); Ransom.Nuke (Symantec); Ransom.Nuke (Malwarebytes)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

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

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

It connects to certain websites to send and receive information. It gathers information and reports it to its servers.

  TECHNICAL DETAILS

File Size: 101,888 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 12 Oct 2016
Payload: Connects to URLs/IPs, Steals information, Displays graphics/image, Displays message/message boxes, Encrypts files

Arrival Details

This Trojan 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 Trojan drops the following files:

  • {folder where files are encrypted}\!!_RECOVERY_instructions_!!.html -> Ransom Note
  • {folder where files are encrypted}\!!_RECOVERY_instructions_!!.txt -> Ransom Note
  • %Application Data%\Microsoft\!!_RECOVERY_instructions_!!.html -> Ransom Note
  • %Application Data%\Microsoft\!!_RECOVERY_instructions_!!.txt -> Ransom Note
  • %Desktop%\!!_RECOVERY_instructions_!!.html -> Ransom Note
  • %Desktop%\!!_RECOVERY_instructions_!!.txt -> Ransom Note
  • %Application Data%\Nuclear55\desktop_wallpaper.bmp -> Ransom Note, image used as wallpaper

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %Desktop% is the desktop folder, where it usually is C:\Documents and Settings\{user name}\Desktop in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\Desktop in Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It creates the following folders:

  • %Application Data%\Nuclear55

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Autostart Technique

This Trojan creates the following registry entries to enable automatic execution of dropped component at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
nuke_html = "%Application Data%\Microsoft\!!_RECOVERY_instructions_!!.html"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\Nuclear55

It adds the following registry entries as part of its installation routine:

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = "%Application Data%\Nuclear55\desktop_wallpaper.bmp"

HKEY_CURRENT_USER\Control Panel\Desktop
TileWallpaper = "0"

HKEY_CURRENT_USER\Control Panel\Desktop
WallpaperStyle = "0"

Other Details

This Trojan connects to the following website to send and receive information:

  • http://{BLOCKED}ol.com/hello.php

It encrypts files with the following extensions:

  • pdf
  • gif
  • bmp
  • jpeg
  • jpg
  • xlsb
  • xlsm
  • xlsx
  • xls
  • png
  • pst
  • doc
  • docx
  • ppt
  • ptx
  • psd
  • pdn
  • txt
  • zip
  • xlr
  • csv
  • 7z
  • mp3
  • mp4
  • mov
  • avi
  • wmv
  • flv
  • dcr
  • swf
  • php
  • htm
  • html
  • js
  • backup
  • dat
  • data
  • sql
  • msg
  • css
  • odb
  • odt
  • odm
  • odc
  • wps
  • rtf
  • ai
  • sav
  • raw
  • old
  • r3d
  • mdb
  • dng
  • 3fr
  • nef
  • jpe
  • accdb
  • srw
  • db
  • pdb
  • dbf
  • tex
  • pages
  • pps
  • key
  • sdf
  • xml
  • mpa
  • mid
  • m3u
  • 3gp
  • 3g2
  • mpg
  • 3ds
  • 3dm
  • eps
  • ps
  • svg
  • zi
  • px
  • cs
  • fla
  • cpp
  • dtd
  • java
  • vb
  • bak
  • py
  • vcx
  • proj
  • sln
  • rar
  • xhtml
  • prc
  • cer
  • rm
  • log
  • u3
  • dcf
  • conf
  • aes
  • ico

It renames encrypted files using the following names:

  • {random characters}.nuclear55

It does the following:

  • It prevents encrypting files containing any of the following strings in its full path name:
    • Downloads
    • Users
    • NVIDIA
    • Intel
    • Documents and Settings
    • Windows
    • ProgramFiles
    • ProgramFiles(x86)
    • System Volume Information
    • Recycler
    • ProgramData
    • PerfLogs
    • Config.Msi
    • $Recyle.Bin
    • .enc
    • Nuclear55
    • files.dat
  • It deletes shadow copies by executing the following command:
    • vssadmin delete shadows /all /quiet

It gathers the following information and reports it to its servers:

  • Computer Name

NOTES:

This ransomware stores the backup of the original wallpaper registry entry at:

  • HKEY_CURRENT_USER\Software\Nuclear55 Wallpaper = "{original wallpaper}"

    It also changes the wallpaper with the following image:

    It drops the following ransom note:

  •   SOLUTION

    Minimum Scan Engine: 9.800
    FIRST VSAPI PATTERN FILE: 12.832.08
    FIRST VSAPI PATTERN DATE: 12 Oct 2016
    VSAPI OPR PATTERN File: 12.833.00
    VSAPI OPR PATTERN Date: 13 Oct 2016

    Step 1

    Before doing any scans, Windows XP, Windows Vista, and Windows 7 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

    Restart in Safe Mode

    [ Learn More ]

    Step 4

    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_CURRENT_USER\Software
      • Nuclear55

    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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
      • nuke_html = "%Application Data%\Microsoft\!!_RECOVERY_instructions_!!.html"

    Step 6

    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.
    • %Application Data%\Nuclear55

    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.
    • %Application Data%\Microsoft\!!_RECOVERY_instructions_!!.html
    • %Application Data%\Microsoft\!!_RECOVERY_instructions_!!.txt
    • %Desktop%\!!_RECOVERY_instructions_!!.html
    • %Desktop%\!!_RECOVERY_instructions_!!.txt
    • {folder where files are encrypted}\!!_RECOVERY_instructions_!!.html
    • {folder where files are encrypted}\!!_RECOVERY_instructions_!!.txt

    Step 8

    Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_NUCLEAR.F116JC. 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.

    Step 9

    Reset your Desktop properties

    [ Learn More ]

    Step 10

    Restore encrypted files from backup.


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