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RANSOM_BUD.A

June 13, 2018
 ALIASES:

N/A

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet

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

It deletes the initially executed copy of itself.

It encrypts files with specific file extensions.

  TECHNICAL DETAILS

File Size:

484,352 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

21 Sep 2017

Payload:

Displays message/message boxes, Encrypts files

Arrival Details

This Ransomware 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 Ransomware drops the following files:

  • %Application Data%\System32Work\EncryptedFileList.txt - List of encrypted files
  • %Application Data%\System32Work\Address.txt - Bitcoin address where the ransom should be paid
  • %Application Data%\System32Work\dr - If the ransomware is run while this file exists, it will delete 1000 files

(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.)

It drops the following copies of itself into the affected system:

  • %Application Data%\Corel\RegisterCGS.exe
  • %AppDataLocal%\Corel\CorelCGS.exe

(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.. %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local 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 Ransomware adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
RegisterCGS.exe = %Application Data%\Corel\RegisterCGS.exe

Other System Modifications

This Ransomware adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableTaskMgr = 1

Other Details

This Ransomware does the following:

  • Deletes 1000 files if the user restarts the affected system
  • Deletes 1 file every hour unil the ransom is paid
  • Shows a window that serves a ransom note:

It deletes the initially executed copy of itself

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .3dm
  • .3ds
  • .3g2
  • .3gp
  • .7z
  • .7zip
  • .aa3
  • .aaf
  • .accdb
  • .aep
  • .aepx
  • .aet
  • .ai
  • .ai
  • .aif
  • .amr
  • .apnx
  • .as
  • .as3
  • .asf
  • .asp
  • .aspx
  • .asx
  • .avhd
  • .avi
  • .azw
  • .azw1
  • .azw3
  • .azw4
  • .bmp
  • .c
  • .cdi
  • .cer
  • .cgi
  • .class
  • .cpp
  • .cs
  • .csv
  • .dat
  • .db
  • .dbf
  • .der
  • .doc
  • .docb
  • .docm
  • .docx
  • .dot
  • .dotm
  • .dotx
  • .dwg
  • .dxf
  • .efx
  • .emf
  • .eml
  • .eps
  • .epub
  • .fla
  • .flv
  • .gfx
  • .gif
  • .gzip
  • .h
  • .htm
  • .html
  • .idml
  • .iff
  • .indb
  • .indd
  • .indl
  • .indt
  • .inx
  • .iso
  • .jar
  • .java
  • .jfif
  • .jge
  • .jpe
  • .jpeg
  • .jpg
  • .js
  • .json
  • .kdbx
  • .key
  • .key
  • .lit
  • .m3u
  • .m3u8
  • .m4a
  • .m4u
  • .max
  • .mdb
  • .mid
  • .mkv
  • .mobi
  • .mov
  • .mp1
  • .mp2
  • .mp3
  • .mp4
  • .mp4v
  • .mpa
  • .mpeg
  • .mpg
  • .msg
  • .myi
  • .nrg
  • .nri
  • .odc
  • .odf
  • .odp
  • .ods
  • .odt
  • .p12
  • .p7b
  • .p7c
  • .pbk
  • .pdb
  • .pdf
  • .pem
  • .pfx
  • .php
  • .plb
  • .pmd
  • .png
  • .pot
  • .potm
  • .potx
  • .ppam
  • .ppj
  • .pps
  • .ppsm
  • .ppsx
  • .ppt
  • .pptm
  • .pptx
  • .prel
  • .prproj
  • .ps
  • .ps
  • .psd
  • .psd
  • .pspimage
  • .pst
  • .pub
  • .pvi
  • .py
  • .py
  • .pyc
  • .ra
  • .rar
  • .raw
  • .rb
  • .rtf
  • .sdf
  • .ses
  • .sldm
  • .sldx
  • .sln
  • .sql
  • .sql
  • .svg
  • .swf
  • .tar
  • .tga
  • .tif
  • .tiff
  • .txt
  • .vbox
  • .vbs
  • .vcb
  • .vcf
  • .vfd
  • .vlc
  • .vmc
  • .vmdk
  • .vmsd
  • .vmx
  • .vob
  • .vsdx
  • .vsv
  • .wav
  • .wma
  • .wmv
  • .work
  • .wpd
  • .wps
  • .xla
  • .xlam
  • .xll
  • .xlm
  • .xls
  • .xlsb
  • .xlsm
  • .xlsx
  • .xlt
  • .xltm
  • .xltx
  • .xlw
  • .xml
  • .xqx
  • .xqx
  • .xvd
  • .yuv
  • .zip

It avoids encrypting files found in the following folders:

  • %Application Data%\System32Work
  • C:\Windows

(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.)

It appends the following extension to the file name of the encrypted files:

  • .bud

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.672.04

FIRST VSAPI PATTERN DATE:

21 Sep 2017

VSAPI OPR PATTERN File:

13.673.00

VSAPI OPR PATTERN Date:

22 Sep 2017

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 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\Policies\System
    • DisableTaskMgr = 1
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • RegisterCGS.exe = %Application Data%\Corel\RegisterCGS.exe

Step 5

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%\Corel
  • %AppDataLocal%\Corel
  • %Application Data%\System32Work

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_BUD.A. 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 7

Restore encrypted files from backup.


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