RANSOM_SIGMA.B
Trojan:Win32/Tiggre!rfn (Microsoft); W32/Kryptik.L!tr.ransom (Fortinet); Trojan.Ransom.Sigma (ALYac)
Windows
Threat Type: Ransomware
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
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
3,276,073 bytes
EXE
Yes
30 Nov 2017
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
- .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
9.850
13.816.05
01 Dec 2017
13.817.00
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
Step 4
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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- chrome = "Rundll32.exe SHELL32.DLL,ShellExec_RunDLL %Application Data%\Microsoft\{GUID 32 Hex Values}\taskwgr.exe"
- chrome = "Rundll32.exe SHELL32.DLL,ShellExec_RunDLL %Application Data%\Microsoft\{GUID 32 Hex Values}\taskwgr.exe"
Step 5
Search and delete these folders
- %Application Data%\Microsoft\{GUID 32 Hex Values}
Step 6
Search and delete these files
- %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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