Analysis by: Mio Fidel Villena
ALIASES:

Ransom.CryptXXX (NORTON), TR/RedCap.khogd (ANTIVIR), Ransom:MSIL/Natiris.A (MICROSOFT)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Dropped by other malware

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: 124,928 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 27 Nov 2017
Payload: Drops files, Encrypts files, Displays message/message boxes

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:

  • %User Temp%\wallpaper.bmp
  • %Desktop%\sys.bat <-used to terminate the ransomware

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp 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 adds the following mutexes to ensure that only one of its copies runs at any one time:

  • KristinaCS

Other System Modifications

This Ransomware adds the following registry keys:

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = %User Temp%\wallpaper.bmp

It sets the system's desktop wallpaper to the following image:

Other Details

This Ransomware does the following:

  • Can perform encryption routine on all different directories found at the same time
  • Exits and deletes itself only after performing all the encryption routines
  • Execute the following commands usind CMD
    /C net view

Ransomware Routine

This Ransomware avoids encrypting files with the following strings in their file name:

  • .crypt12
  • .tmp
  • .sep
  • .tlb
  • .tbl
  • .tsp
  • .cmd
  • .ax
  • .olb
  • .com
  • .acm
  • .edb
  • .ini
  • .exe
  • .386
  • .73u
  • .8xu
  • .adm
  • .adml
  • .admx
  • .ani
  • .ann
  • .aos
  • .asec
  • .bio
  • .bk2
  • .blf
  • .bmk
  • .bud
  • .cab
  • .cdmp
  • .chs
  • .ci
  • .cnt
  • .cpi
  • .cpl
  • .cpq
  • .cur
  • .desklink
  • .deskthemepack
  • .dev
  • .diagcab
  • .diagcfg
  • .diagpkg
  • .dimax
  • .dit
  • .drv
  • .dss
  • .dyc
  • .ebd
  • .efi
  • .evtx
  • .ffa
  • .ffl
  • .ffo
  • .ffx
  • .ftg
  • .fts
  • .gmmp
  • .grl
  • .group
  • .grp
  • .h1s
  • .hdmp
  • .hhc
  • .hhk
  • .hiv
  • .hlp
  • .hpj
  • .hsh
  • .htt
  • .icl
  • .icns
  • .ico
  • .idi
  • .ifw
  • .ime
  • .img3
  • .inf_loc
  • .ins
  • .ion
  • .ipod
  • .itemdata-ms
  • .its
  • .jpn
  • .kbd
  • .key
  • .kor
  • .library-ms
  • .lnk
  • .log1
  • .log2
  • .lpd
  • .manifest
  • .mapimail
  • .mdmp
  • .mi4
  • .mlc
  • .mobileconfig
  • .msc
  • .msp
  • .msstyle
  • .msstyles
  • .mui
  • .mui_cccd5ae0
  • .mum
  • .mydocs
  • .nb0
  • .nbh
  • .nfo
  • .nls
  • .nt
  • .ntfs
  • .p7b
  • .pck
  • .pdr
  • .pfx
  • .pid
  • .pk2
  • .pol
  • .ppd
  • .prefpane
  • .prf
  • .printerexport
  • .ps2
  • .pwl
  • .rc1
  • .rc2
  • .rco
  • .reg
  • .regtrans-ms
  • .rfw
  • .rmt
  • .rs
  • .ruf
  • .savedsearch
  • .sbn
  • .scap
  • .scf
  • .scr
  • .shd
  • .shsh
  • .swp
  • .sys
  • .tdz
  • .tha
  • .theme
  • .trx_dll
  • .uce
  • .vga
  • .vgd
  • .vx_
  • .vxd
  • .webpnp
  • .wer
  • .wph
  • .wpx
  • .xfb
  • .xrm-ms
  • .dat
  • .db
  • .dll
  • .dmp
  • .ics
  • .mod
  • .mpa
  • .msu
  • .nomedia
  • .ocx
  • .ps1
  • .rom
  • .rtp
  • .shs
  • .spl
  • .themepack
  • .0
  • .000
  • .amlv
  • .automaticdestinations-ms
  • .bashrc
  • .bash_history
  • .bash_profile
  • .bin
  • .bk1
  • .bom
  • .c32
  • .cat
  • .cgz
  • .chg
  • .chk
  • .cht
  • .clb
  • .cpr
  • .crash
  • .dlx
  • .dvd
  • .edj
  • .elf
  • .emerald
  • .etl
  • .evt
  • .fid
  • .fpbf
  • .help
  • .idx
  • .ius
  • .job
  • .lfs
  • .lockfile
  • .lst
  • .mbr
  • .mem
  • .metadata_never_index
  • .panic
  • .pat
  • .pit
  • .pnf
  • .ppm
  • .profile
  • .prt
  • .qvm
  • .saver
  • .sbf
  • .schemas
  • .sdb
  • .searchconnector-ms
  • .sfcache
  • .so.0
  • .sqm
  • .str
  • .wdf
  • .wdgt
  • .wgz
  • .zone.identifier

It avoids encrypting files found in the following folders:

  • D:\owncloud
  • D:\gdrive

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

  • ={Random 5 Digit Number}=hello@boomfile.ru.crypt12

It drops the following file(s) as ransom note:

  • {Folder Path of Encrypted Files}\!!!!readme!!!.txt

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.810.08
FIRST VSAPI PATTERN DATE: 28 Nov 2017
VSAPI OPR PATTERN File: 13.811.00
VSAPI OPR PATTERN Date: 29 Nov 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

Reset your Desktop properties

[ 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.
  • %User Temp%\wallpaper.bmp
  • {Folder Path of Encrypted Files}\!!!!readme!!!.txt

Step 5

Scan your computer with your Trend Micro product to delete files detected as RANSOM_CRYPTWELVE.B. 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 the following Trend Micro Support pages for more information:

Step 6

Restore encrypted files from backup.


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