Ransom.Win32.DELSHAD.F
Trojan.DelShad (VBA32)
Windows
Threat Type: Ransomware
Destructiveness: No
Encrypted: No
In the wild: Yes
OVERVIEW
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 executes then deletes itself afterward.
It drops files as ransom note.
TECHNICAL DETAILS
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 copies of itself into the affected system:
- %Common Startup%\windows-update-CVE-wFW.exe
(Note: %Common Startup% is the startup folder for all users, which is usually C:\Documents and Settings\All Users\Start Menu\Programs\Startup on Windows 2000, XP, and Server 2003, or C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)
It adds the following processes:
- %System%\cmd.exe /C "reg ADD HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System /v EnableLUA /t REG_DWORD /d 0 /f"
- cmd /C vssadmin Delete Shadows /All /Quiet
- cmd /C "rd /s /q {Drive}:\$RECYCLE.BIN\"
(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)
It executes then deletes itself afterward.
Other Details
This Ransomware encrypts files with the following extensions:
- accdb
- adx
- aes
- allg
- allp
- argp=
- array
- asc
- asf
- asm
- asn1
- asp
- avi
- avx
- avx2
- bak
- base
- bat
- bind
- bmi1
- bmi2
- bmp
- bool
- brd
- bz2
- call
- cap
- cas1
- cas2
- cas3
- cas4
- cas5
- cas6
- cgm
- chan
- chdir
- class
- close
- cmd
- cpp
- crt
- csr
- csv
- dbf
- dch
- de-DE
- dead
- defer
- der
- dif
- dip
- dir
- djvu
- doc
- docb
- docm
- docx
- dot
- dotm
- dotx
- dwg
- edb
- eEpP
- eml
- en-US
- end
- erms
- es-ES
- fail
- false
- fault
- file
- fin
- fla
- flv
- fma
- fr-FR
- frm
- ftp
- ftps
- func
- gc
- gcing
- gFree
- gif
- gp
- gpg
- gscan
- hchan
- hour
- hpp
- html
- http
- https
- hwp
- ibd
- icmp
- idle
- igmp
- imap2
- imap3
- imaps
- int
- int16
- int32
- int64
- int8
- ip4
- iso
- it-IT
- itab
- ja-JA
- jar
- java
- jpeg
- jpg
- jsp
- kdb
- key
- keys
- kind
- ko_KR
- lay
- lay6
- ldf
- link
- m3u
- m4u
- map
- match
- max
- mdb
- mdf
- mheap
- mid
- mkv
- mml
- month
- mov
- mp3
- mp4
- mpeg
- mpg
- msg
- myd
- myi
- nan
- nef
- nil
- ntohs
- obj
- odb
- odg
- odp
- ods
- odt
- open
- ost
- otg
- otp
- ots
- ott
- p12
- panic
- pas
- path
- pc=
- pem
- pfx
- php
- pipe
- png
- pop3
- pop3s
- pot
- potm
- potx
- ppam
- pps
- ppsm
- ppsx
- ppt
- pptm
- pptx
- prof
- ps1
- psd
- pst
- pt-BR
- ptr
- quit
- rar
- raw
- read
- root
- rtf
- ru
- ru2
- runas
- rune
- sbrk
- scav
- sch
- sched
- sldm
- sldx
- sleep
- slice
- slk
- sln
- smtp
- snt
- spine
- sql
- sse2
- sse3
- sse41
- sse42
- ssh
- ssse3
- stc
- std
- sti
- stw
- sudog
- suo
- svg
- svqxX
- sweep
- swf
- sxc
- sxd
- sxi
- sxm
- sxw
- sync
- tag:
- tar
- tbk
- tcp
- tcp4
- tgz
- tif
- tiff
- tlp
- tmp
- to
- trace
- true
- txt
- udp
- udp4
- uint
- uint8
- uop
- uot
- usage
- vbs
- vcd
- vdi
- vm
- vmdk
- vmx
- vob
- vsd
- vsdx
- wav
- wb2
- wk1
- wks
- wma
- wmv
- write
- xlc
- xlm
- xls
- xlsb
- xlsm
- xlsx
- xlt
- xltm
- xltx
- xlw
- zh-CN
- zh-HK
- zh-TW
- zip
It does the following:
- It renames encrypted as {Base64-encoded original filename}.lockedv1.
- It ensures that it executes with administrative privileges.
Ransomware Routine
This Ransomware drops the following file(s) as ransom note:
- {Encrypted directory}\READMEV1.txt
- %Common Startup%\READMEV1.txt
SOLUTION
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.XXPE50FFF039
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
Step 5
Delete this registry value
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\Policies\System
- EnableLUA=0
- EnableLUA=0
Step 6
Search and delete these files
- %Common Startup%\windows-update-CVE-wFW.exe
- {Encrypted directory}\READMEV1.txt
- %Common Startup%\READMEV1.txt
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win32.DELSHAD.F. 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 8
Restore encrypted files from backup.
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