RANSOM_SIGMA.B


 ALIASES:

Trojan:Win32/Tiggre!rfn (Microsoft); W32/Kryptik.L!tr.ransom (Fortinet); Trojan.Ransom.Sigma (ALYac)

 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, 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 steals certain information from the system and/or the user.

It connects to certain websites to send and receive information. It terminates itself if it detects it is being run in a virtual environment. It is capable of encrypting files in the affected system.

It encrypts files with specific file extensions. It encrypts files found in specific folders. It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

3,276,073 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

30 Nov 2017

Payload:

Drops files, Encrypts files, Collects system information, Connects to URLs/IPs, Displays graphics/image, 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 a copy of itself in the following folders using different file names:

  • %Application Data%\Microsoft\{GUID 32 Hex Values}\taskwgr.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.)

It drops the following file(s)/component(s):

  • %Application Data%\tor\lock
  • %Application Data%\tor\state.tmp
  • %Application Data%\tor\unverified-microdesc-consensus.tmp
  • %Application Data%\tor\cached-certs.tmp
  • %Application Data%\tor\cached-microdesc-consensus.tmp
  • %Application Data%\tor\cached-microdescs.new
  • %Application Data%\tor\state.tmp
  • %Application Data%\Microsoft\{GUID 32 Hex Values}\System.zip
  • %Application Data%\Microsoft\{GUID 32 Hex Values}\Data\Tor\geoip
  • %Application Data%\Microsoft\{GUID 32 Hex Values}\Data\Tor\geoip6
  • %Application Data%\Microsoft\{GUID 32 Hex Values}\Tor\libeay32.dll
  • %Application Data%\Microsoft\{GUID 32 Hex Values}\Tor\libevent-2-0-5.dll
  • %Application Data%\Microsoft\{GUID 32 Hex Values}\Tor\libevent_core-2-0-5.dll
  • %Application Data%\Microsoft\{GUID 32 Hex Values}\Tor\libevent_extra-2-0-5.dll
  • %Application Data%\Microsoft\{GUID 32 Hex Values}\Tor\libgcc_s_sjlj-1.dll
  • %Application Data%\Microsoft\{GUID 32 Hex Values}\Tor\libssp-0.dll
  • %Application Data%\Microsoft\{GUID 32 Hex Values}\Tor\ssleay32.dll
  • %Application Data%\Microsoft\{GUID 32 Hex Values}\Tor\tor-gencert.exe
  • %Application Data%\Microsoft\{GUID 32 Hex Values}\Tor\tor.exe
  • %Application Data%\Microsoft\{GUID 32 Hex Values}\Tor\zlib1.dll

(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 and executes the following files:

  • %Application Data%\Microsoft\{GUID 32 Hex Values}\Tor\svchost.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.)

It creates the following folders:

  • %Application Data%\Microsoft\{GUID 32 Hex Values}

(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 Ransomware adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
chrome = Rundll32.exe SHELL32.DLL,ShellExec_RunDLL %Application Data%\Microsoft\{GUID 32 Hex Values}\taskwgr.exe

Other System Modifications

This Ransomware sets the system's desktop wallpaper to the following image:

Information Theft

This Ransomware steals the following information:

  • Username
  • OS
  • Machine Name
  • No. of Files Encrypted
  • Country

Other Details

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

  • http://{BLOCKED}qj7azyldq2.{BLOCKED}n/control.php

It terminates itself if it detects it is being run in a virtual environment.

It does the following:

  • It executes this command if it detects it is being debugged or when run in virtual environment.
  • - cmd.exe /C ping 1.1.1.1 -n 1 -w 3000 > Nul & Del "{Initial Malware Path}\{Malware Name}.exe"

It is capable of encrypting files in the affected system.

It checks if the following virtual machine or sandbox related module(s) is loaded in the affected system:

  • VBoxHook.dll
  • SbieDll.dll

It does not proceed to its malicious routine if it detects that it is being debugged.

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .iso
  • .sln
  • .suo
  • .1cd
  • .3d
  • .3d4
  • .3df8
  • .3dm
  • .3ds
  • .3fr
  • .3g2
  • .3gp
  • .3gp2
  • .3mm
  • .3pr
  • .7z
  • .7zip
  • .aac
  • .ab4
  • .abk
  • .abw
  • .ac3
  • .accdb
  • .accde
  • .accdr
  • .accdt
  • .ace
  • .ach
  • .acr
  • .act
  • .adb
  • .ade
  • .adi
  • .adp
  • .adpb
  • .adr
  • .ads
  • .adt
  • .agdl
  • .ai
  • .aiff
  • .aim
  • .aip
  • .ais
  • .ait
  • .al
  • .amf
  • .amr
  • .amu
  • .amx
  • .amxx
  • .ans
  • .aoi
  • .ap
  • .ape
  • .api
  • .apj
  • .arc
  • .ari
  • .arj
  • .aro
  • .arr
  • .arw
  • .asa
  • .asc
  • .ascx
  • .ase
  • .asf
  • .ashx
  • .asm
  • .asmx
  • .asp
  • .aspx
  • .asr
  • .asx
  • .avi
  • .avs
  • .awg
  • .back
  • .backup
  • .backupdb
  • .bak
  • .bank
  • .bay
  • .bck
  • .bdb
  • .bdp
  • .bdr
  • .bgt
  • .bib
  • .bic
  • .big
  • .bik
  • .bin
  • .bkf
  • .bkp
  • .blend
  • .blp
  • .bmc
  • .bmf
  • .bml
  • .bmp
  • .boc
  • .bp2
  • .bp3
  • .bpl
  • .bpw
  • .bsp
  • .c
  • .cag
  • .cam
  • .cap
  • .car
  • .cbr
  • .cbz
  • .cc
  • .ccd
  • .cch
  • .cd
  • .cdf
  • .cdr
  • .cdr3
  • .cdr4
  • .cdr5
  • .cdr6
  • .cdrw
  • .cdx
  • .ce1
  • .ce2
  • .cer
  • .cfg
  • .cgf
  • .cgm
  • .chk
  • .cib
  • .class
  • .clr
  • .cls
  • .cms
  • .cmt
  • .cod
  • .col
  • .config
  • .contact
  • .cp
  • .cpi
  • .cpp
  • .cr2
  • .craw
  • .crd
  • .crt
  • .crw
  • .cs
  • .csh
  • .csi
  • .csl
  • .cso
  • .css
  • .csv
  • .ctt
  • .cty
  • .cwf
  • .dac
  • .dal
  • .dap
  • .dat
  • .db
  • .db3
  • .db_journal
  • .dbb
  • .dbf
  • .dbx
  • .dc2
  • .dcp
  • .dcr
  • .dcs
  • .dcu
  • .ddc
  • .ddcx
  • .ddd
  • .ddoc
  • .ddrw
  • .dds
  • .dem
  • .der
  • .des
  • .design
  • .dev
  • .dex
  • .dgc
  • .dic
  • .dif
  • .dii
  • .dir
  • .disk
  • .dit
  • .divx
  • .diz
  • .djvu
  • .dmg
  • .dng
  • .dob
  • .doc
  • .docm
  • .docx
  • .dot
  • .dotm
  • .dotx
  • .dox
  • .dpk
  • .dpl
  • .dpr
  • .drf
  • .drw
  • .dsk
  • .dsp
  • .dtd
  • .dvd
  • .dvi
  • .dvx
  • .dwg
  • .dxb
  • .dxe
  • .dxf
  • .dxg
  • .edb
  • .elf
  • .eml
  • .eps
  • .eql
  • .erbsql
  • .erf
  • .err
  • .euc
  • .evo
  • .ex
  • .exf
  • .exif
  • .f90
  • .faq
  • .fcd
  • .fdb
  • .fdr
  • .fds
  • .ff
  • .ffd
  • .fff
  • .fh
  • .fhd
  • .fla
  • .flac
  • .flf
  • .flp
  • .flv
  • .flvv
  • .for
  • .fpp
  • .fpx
  • .fxg
  • .gam
  • .gif
  • .gray
  • .grey
  • .grf
  • .groups
  • .gry
  • .gthr
  • .gz
  • .gzig
  • .h
  • .h3m
  • .h4r
  • .hbk
  • .hdd
  • .hpp
  • .htm
  • .html
  • .ibank
  • .ibd
  • .ibz
  • .idx
  • .iif
  • .iiq
  • .img
  • .incpas
  • .indd
  • .ink
  • .ipa
  • .isu
  • .isz
  • .itdb
  • .itl
  • .iwd
  • .jar
  • .jav
  • .java
  • .jc
  • .jfif
  • .jgz
  • .jif
  • .jiff
  • .jnt
  • .jpc
  • .jpe
  • .jpeg
  • .jpf
  • .jpg
  • .jpw
  • .js
  • .kc2
  • .kdbx
  • .kdc
  • .key
  • .kmz
  • .kpdx
  • .kwd
  • .kwm
  • .laccdb
  • .lbi
  • .lcd
  • .lcf
  • .ldb
  • .ldf
  • .lgp
  • .lit
  • .log
  • .lp2
  • .ltm
  • .ltr
  • .lua
  • .lvl
  • .m
  • .m2ts
  • .m3u
  • .m4p
  • .m4v
  • .mag
  • .man
  • .map
  • .mapimail
  • .max
  • .mbox
  • .mbx
  • .mcd
  • .md
  • .md3
  • .mdb
  • .mdc
  • .mdf
  • .mdl
  • .mdn
  • .mds
  • .mef
  • .mfw
  • .mic
  • .mid
  • .mip
  • .mkv
  • .mlb
  • .mlx
  • .mmw
  • .mny
  • .mod
  • .moneywell
  • .mos
  • .mov
  • .moz
  • .mp3
  • .mp4
  • .mpeg
  • .mpg
  • .mrw
  • .msg
  • .msp
  • .mxp
  • .myd
  • .nav
  • .ncd
  • .nd
  • .ndd
  • .ndf
  • .nds
  • .nef
  • .nfo
  • .nk2
  • .nop
  • .now
  • .nrg
  • .nri
  • .nrw
  • .ns2
  • .ns3
  • .ns4
  • .nsd
  • .nsf
  • .nsg
  • .nsh
  • .nvram
  • .nwb
  • .nx2
  • .nxl
  • .nyf
  • .oab
  • .obj
  • .odb
  • .odc
  • .odf
  • .odg
  • .odi
  • .odm
  • .odp
  • .ods
  • .odt
  • .oft
  • .oga
  • .ogg
  • .oil
  • .opf
  • .orf
  • .ost
  • .otg
  • .oth
  • .otp
  • .ots
  • .ott
  • .owl
  • .oxt
  • .p12
  • .p7b
  • .p7c
  • .pab
  • .pages
  • .pak
  • .pas
  • .pat
  • .pbf
  • .pbp
  • .pbs
  • .pcd
  • .pct
  • .pcv
  • .pdb
  • .pdd
  • .pdf
  • .pef
  • .pem
  • .pfx
  • .php
  • .pif
  • .pkb
  • .pkh
  • .pl
  • .plc
  • .pli
  • .plus_muhd
  • .pm
  • .png
  • .pot
  • .potm
  • .potx
  • .ppam
  • .ppd
  • .ppf
  • .pps
  • .ppsm
  • .ppsx
  • .ppt
  • .pptm
  • .pptx
  • .prc
  • .prf
  • .prt
  • .ps
  • .psa
  • .psafe3
  • .psd
  • .pspimage
  • .py
  • .pst
  • .ptx
  • .puz
  • .pwf
  • .pwi
  • .pwm
  • .pxp
  • .py
  • .qba
  • .qbb
  • .qbm
  • .qbr
  • .qbw
  • .qbx
  • .qby
  • .qcow
  • .qcow2
  • .qdf
  • .qed
  • .qel
  • .qif
  • .qpx
  • .qtq
  • .qtr
  • .r3d
  • .ra
  • .raf
  • .rar
  • .rat
  • .raw
  • .rdb
  • .res
  • .rev
  • .rgn
  • .rm
  • .rng
  • .rrt
  • .rsrc
  • .rsw
  • .rte
  • .rtf
  • .rts
  • .rtx
  • .rum
  • .run
  • .rv
  • .rvt
  • .rw2
  • .rwl
  • .rwz
  • .s3db
  • .sad
  • .saf
  • .safe
  • .sas7bdat
  • .sav
  • .save
  • .say
  • .scm
  • .scn
  • .scx
  • .sd0
  • .sda
  • .sdb
  • .sdc
  • .sdf
  • .sdn
  • .sds
  • .sdt
  • .sen
  • .sfs
  • .sfx
  • .sh
  • .shar
  • .shr
  • .shw
  • .sldm
  • .sldx
  • .slt
  • .snp
  • .so
  • .spr
  • .sql
  • .sqlite
  • .sqlite3
  • .sqlitedb
  • .sqx
  • .sr2
  • .srf
  • .srt
  • .srw
  • .ssa
  • .st4
  • .st5
  • .st6
  • .st7
  • .st8
  • .stc
  • .std
  • .sti
  • .stm
  • .stt
  • .stw
  • .stx
  • .sud
  • .svg
  • .svi
  • .svr
  • .swd
  • .swf
  • .sxc
  • .sxd
  • .sxg
  • .sxi
  • .sxm
  • .sxw
  • .tar
  • .tax2013
  • .tax2014
  • .tbz2
  • .tch
  • .tcx
  • .tex
  • .txt
  • .text
  • .tg
  • .tga
  • .thm
  • .thmx
  • .tif
  • .tlg
  • .tlz
  • .tpu
  • .tpx
  • .trp
  • .tu
  • .tur
  • .txd
  • .txf
  • .txt
  • .uax
  • .udf
  • .umx
  • .unr
  • .unx
  • .uop
  • .upoi
  • .url
  • .usa
  • .usx
  • .ut2
  • .ut3
  • .utc
  • .utx
  • .uvx
  • .uxx
  • .val
  • .vbox
  • .vc
  • .vcd
  • .vdi
  • .vdo
  • .ver
  • .vhd
  • .vhdx
  • .vmdk
  • .vmf
  • .vmsd
  • .vmt
  • .vmx
  • .vmxf
  • .vob
  • .vsi
  • .vtf
  • .w3g
  • .w3x
  • .wab
  • .wad
  • .wallet
  • .war
  • .wav
  • .wave
  • .waw
  • .wb2
  • .wbk
  • .wdgt
  • .wks
  • .wm
  • .wma
  • .wmd
  • .wmdb
  • .wmmp
  • .wmv
  • .wmx
  • .wow
  • .wpd
  • .wpk
  • .wpl
  • .wps
  • .wsh
  • .wtd
  • .wtf
  • .wvx
  • .x11
  • .x3f
  • .xis
  • .xl
  • .xla
  • .xlam
  • .xlc
  • .xlk
  • .xll
  • .xlm
  • .xlr
  • .xls
  • .xlsb
  • .xlsm
  • .xlsx
  • .xlt
  • .xltm
  • .xltx
  • .xlv
  • .xlw
  • .xlwx
  • .xml
  • .xpi
  • .xpt
  • .xvid
  • .xwd
  • .yab
  • .ycbcra
  • .yps
  • .yuv
  • .z02
  • .z04
  • .zap
  • .zip
  • .zipx
  • .zoo
  • .saz
  • .tlp
  • .enc
  • .bas
  • .frm
  • .pas
  • .vbs
  • .json

It encrypts files found in the following folders:

  • {All Drives}

It avoids encrypting files with the following strings in their file path:

  • AppData
  • RECYCLER
  • All Users
  • Program Files
  • Program Files (x86)
  • ProgramData
  • Windows
  • WINDOWS
  • system32

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

  • {Malware Path}\ReadMe.html
  • {Encrypted Folder}\ReadMe.txt

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.816.05

FIRST VSAPI PATTERN DATE:

01 Dec 2017

VSAPI OPR PATTERN File:

13.817.00

VSAPI OPR PATTERN Date:

02 Dec 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\Run
    • chrome = "Rundll32.exe SHELL32.DLL,ShellExec_RunDLL %Application Data%\Microsoft\{GUID 32 Hex Values}\taskwgr.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%\Microsoft\{GUID 32 Hex Values}

Step 6

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.
  • %Application Data%\tor\lock
  • %Application Data%\tor\state.tmp
  • %Application Data%\tor\unverified-microdesc-consensus.tmp
  • %Application Data%\tor\cached-certs.tmp
  • %Application Data%\tor\cached-microdesc-consensus.tmp
  • %Application Data%\tor\cached-microdescs.new
  • %Application Data%\tor\state.tmp
  • {Malware Path}\ReadMe.html
  • {Encrypted Folder}\ReadMe.txt

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_SIGMA.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 this Knowledge Base page for more information.

Step 8

Restore encrypted files from backup.


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