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RANSOM_DESUI.A

August 17, 2017
 PLATFORM:

Windows

 OVERALL RISK RATING:
 REPORTED INFECTION:

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware, 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 drops files as ransom note.

  TECHNICAL DETAILS

File Size:

369,152 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

06 Jun 2017

Payload:

Drops files, 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.

Process Termination

This Ransomware terminates the following processes if found running in the affected system's memory:

  • explorer
  • ProcessHacker
  • Taskmgr

Ransomware Routine

This Ransomware drops the following file(s) as ransom note:

  • %Desktop%\READ_ME.txt

(Note: %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 leaves text files that serve as ransom notes containing the following text:

  • All your important files have been encrypted! Your files were encrypted with an AES 128 bit encryption and uselessly rendered. In order to make their files usable again they have to pay 0.4250 Bitcoins
  • Do not know what Bitcoin is?https://de.wikipedia.org/wiki/Bitcoin
  • You can buy Bitcoins at http://www.localbitcoins.com and https://blockchain.info/
  • Send 0.4250 BTC to this address: {bitcoin address}

NOTES:
This ransomware does not encrypt any file in your computer, instead the following lockscreen will be displayed:

Pressing Unlock button with UmVhbFZpcnVzXw== as Decryption Key will display the following message box:

It contains uncalled functions that has capability of:

  • Encrypting files in the following folder:
    • %Desktop%
    • %User Profile%\Pictures
    • %User Profile%\Music
    • %User Profile%\Documents
    • %User Profile%\Videos
    • %Application Data%
    • %All Users Profile%\Documents
    • %Application Data%\Microsoft\Windows\Templates
    • %User Profile%\Local Settings\History
    • %Application Data%\Microsoft\Windows\SendTo
    • %Application Data%\Microsoft\Windows\Recent
  • Encrypting files with following extensions:
    • .png
    • .3dm
    • .3g2
    • .3gp
    • .aaf
    • .accdb
    • .aep
    • .aepx
    • .aet
    • .ai
    • .aif
    • .arw
    • .as
    • .as3
    • .asf
    • .asp
    • .asx
    • .avi
    • .bay
    • .bmp
    • .cdr
    • .cer
    • .class
    • .cpp
    • .cr2
    • .crt
    • .crw
    • .cs
    • .csv
    • .db
    • .dbf
    • .dcr
    • .der
    • .dng
    • .doc
    • .docb
    • .docm
    • .docx
    • .dot
    • .dotm
    • .dotx
    • .dwg
    • .dxf
    • .dxg
    • .efx
    • .eps
    • .erf
    • .fla
    • .flv
    • .idml
    • .iff
    • .indb
    • .indd
    • .indl
    • .indt
    • .inx
    • .jar
    • .java
    • .jpeg
    • .jpg
    • .kdc
    • .m3u
    • .m3u8
    • .m4u
    • .max
    • .mdb
    • .mdf
    • .mef
    • .mid
    • .mov
    • .mp3
    • .mp4
    • .mpa
    • .mpeg
    • .mpg
    • .mrw
    • .msg
    • .nef
    • .nrw
    • .odb
    • .odc
    • .odm
    • .odp
    • .ods
    • .odt
    • .orf
    • .p12
    • .p7b
    • .p7c
    • .pdb
    • .pdf
    • .pef
    • .pem
    • .pfx
    • .php
    • .plb
    • .pmd
    • .pot
    • .potm
    • .potx
    • .ppam
    • .ppj
    • .pps
    • .ppsm
    • .ppsx
    • .ppt
    • .pptm
    • .pptx
    • .prel
    • .ps
    • .psd
    • .pst
    • .ptx
    • .r3d
    • .ra
    • .raf
    • .rar
    • .raw
    • .rb
    • .rtf
    • .rw2
    • .rwl
    • .sdf
    • .sldm
    • .sldx
    • .sql
    • .sr2
    • .srf
    • .srw
    • .svg
    • .swf
    • .tif
    • .txt
    • .vcf
    • .vob
    • .wav
    • .wb2
    • .wma
    • .wmv
    • .wpd
    • .wps
    • .x3f
    • .xla
    • .xlam
    • .xlk
    • .xll
    • .xlm
    • .xls
    • .xlsb
    • .xlsm
    • .xlsx
    • .xlt
    • .xltm
    • .xltx
    • .xlw
    • .xml
    • .xqx
    • .zip

    Adding Startup Registry:

  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
  • {unkown} = {malware path}

    •   SOLUTION

    Minimum Scan Engine:

    9.850

    FIRST VSAPI PATTERN FILE:

    13.458.06

    FIRST VSAPI PATTERN DATE:

    08 Jun 2017

    VSAPI OPR PATTERN File:

    13.459.00

    VSAPI OPR PATTERN Date:

    09 Jun 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

    Search and delete these files

    [ 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.
    • %Desktop%\READ_ME.txt

    Step 5

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


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