Analysis by: Marvelous Pelin

 ALIASES:

Ransom:Linux/Erebus.A(Microsoft); Ransom.Erebus(Symantec)

 PLATFORM:

Linux

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Dropped by other malware, Downloaded from the Internet

This malware is a variant of the ransomware family EREBUS and was discovered to be involved in an attack against South Korean webhosting company NAYANA. Users affected by this malware may find their personal files and documents encrypted and thus rendered useless.

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 connects to certain websites to send and receive information. It deletes itself after execution.

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

  TECHNICAL DETAILS

File Size: 429,144 bytes
File Type: ELF
Memory Resident: Yes
Initial Samples Received Date: 13 Jun 2017
Payload: Connects to URLs/IPs, Steals information, 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.

Installation

This Ransomware drops the following files:

  • {malware path}\./{5f58d6f0-bb9c-46e2-a4da-8ebc746f24a5}//log.log ← log file
  • \var\tmp\.{Hash}.conf ← config file

Other Details

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

  • {BLOCKED}.{BLOCKED}.224.128/24

It does the following:

  • It encrypt files with the following filenames:
    • ibdata0
    • ibdata1
    • ibdata2
    • ibdata3
    • ibdata4
    • ibdata5
    • ibdata6
    • ibdata7
    • ibdata8
    • ibdata9
    • ib_logfile0
    • ib_logfile1
    • ib_logfile2
    • ib_logfile3
    • ib_logfile4
    • ib_logfile5
    • ib_logfile6
    • ib_logfile7
    • ib_logfile8
    • ib_logfile9
  • It creates a CRON task to automatically execute itself every hour:
    • /etc/cron.hourly/96anacron
  • It creates a fake Bluetooth service to automatically execute itself every start-up:
    • /etc/rc.d/init.d/bluetooth
    • /etc/rc.d/rc2.d/S25bluetooth
    • /etc/rc.d/rc3.d/S25bluetooth
    • /etc/rc.d/rc4.d/S25bluetooth
    • /etc/rc.d/rc5.d/S25bluetooth
  • It gathers the following information which it sends to its remote server:
    • Private Key
    • Public Key
    • Malware install path
    • Operating System
    • Operating System version and architecture
    • Timezone
    • Language
    • Network Adapter
    • IP Address
    • MAC Address

It deletes itself after execution.

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .1cd
  • .3dm
  • .3ds
  • .3fr
  • .3g2
  • .3gp
  • .3pr
  • .7z
  • .7zip
  • .aac
  • .ab4
  • .abd
  • .accdb
  • .accde
  • .accdr
  • .accdt
  • .ach
  • .acr
  • .act
  • .adb
  • .adp
  • .ads
  • .agdl
  • .ai
  • .aiff
  • .ait
  • .al
  • .aoi
  • .apj
  • .arw
  • .ascx
  • .asf
  • .asm
  • .asp
  • .aspx
  • .asx
  • .atb
  • .avi
  • .awg
  • .back
  • .backup
  • .backupdb
  • .bak
  • .bank
  • .bay
  • .bdb
  • .bgt
  • .bik
  • .bin
  • .bkp
  • .blend
  • .bmp
  • .bpw
  • .bz
  • .bz2
  • .c
  • .cdb
  • .cdf
  • .cdr
  • .cdr3
  • .cdr4
  • .cdr5
  • .cdr6
  • .cdrw
  • .cdx
  • .ce1
  • .ce2
  • .cer
  • .cfg
  • .cfn
  • .cgm
  • .cib
  • .class
  • .cls
  • .cmt
  • .config
  • .contact
  • .cpi
  • .cpp
  • .cr2
  • .craw
  • .crt
  • .crw
  • .cs
  • .csh
  • .csl
  • .css
  • .csv
  • .dac
  • .dat
  • .db
  • .db3
  • .db_journal
  • .dbf
  • .dbx
  • .dc2
  • .dcr
  • .dcs
  • .ddd
  • .ddoc
  • .ddrw
  • .dds
  • .def
  • .der
  • .des
  • .design
  • .dgc
  • .dit
  • .djvu
  • .dng
  • .doc
  • .docm
  • .docx
  • .dot
  • .dotm
  • .dotx
  • .drf
  • .drw
  • .dtd
  • .dwg
  • .dxb
  • .dxf
  • .dxg
  • .edb
  • .eml
  • .eps
  • .erbsql
  • .erf
  • .exf
  • .fdb
  • .ffd
  • .fff
  • .fh
  • .fhd
  • .fla
  • .flac
  • .flb
  • .flf
  • .flv
  • .flvv
  • .fpx
  • .fxg
  • .gif
  • .gray
  • .grey
  • .groups
  • .gry
  • .gz
  • .h
  • .hbk
  • .hdd
  • .hpp
  • .html
  • .ibank
  • .ibd
  • .ibz
  • .idx
  • .iif
  • .iiq
  • .incpas
  • .indd
  • .info
  • .info_
  • .ini
  • .jar
  • .java
  • .jnt
  • .jpe
  • .jpeg
  • .jpg
  • .js
  • .json
  • .kc2
  • .kdbx
  • .kdc
  • .key
  • .kpdx
  • .kwm
  • .laccdb
  • .lck
  • .ldf
  • .lit
  • .lock
  • .log
  • .lua
  • .lz
  • .lz4
  • .lzma
  • .m
  • .m2ts
  • .m3u
  • .m4p
  • .m4v
  • .mab
  • .mapimail
  • .max
  • .mbx
  • .md
  • .mdb
  • .mdc
  • .mdf
  • .mef
  • .mfw
  • .mid
  • .mkv
  • .mlb
  • .mmw
  • .mny
  • .moneywell
  • .mos
  • .mov
  • .mp3
  • .mp4
  • .mpeg
  • .mpg
  • .mrw
  • .msf
  • .msg
  • .myd
  • .nd
  • .ndd
  • .ndf
  • .nef
  • .nk2
  • .nop
  • .nrw
  • .ns2
  • .ns3
  • .ns4
  • .nsd
  • .nsf
  • .nsg
  • .nsh
  • .nvram
  • .nwb
  • .nx2
  • .nxl
  • .nyf
  • .oab
  • .obj
  • .odb
  • .odc
  • .odf
  • .odg
  • .odm
  • .odp
  • .ods
  • .odt
  • .ogg
  • .oil
  • .omg
  • .orf
  • .ost
  • .otg
  • .oth
  • .otp
  • .ots
  • .ott
  • .p12
  • .p7b
  • .p7c
  • .pab
  • .pages
  • .pas
  • .pat
  • .pbf
  • .pcd
  • .pct
  • .pdb
  • .pdd
  • .pdf
  • .pef
  • .pem
  • .pfx
  • .php
  • .pif
  • .pl
  • .plc
  • .plus_muhd
  • .pm
  • .pm!
  • .pmi
  • .pmj
  • .pml
  • .pmm
  • .pmo
  • .pmr
  • .pnc
  • .pnd
  • .png
  • .pnx
  • .pot
  • .potm
  • .potx
  • .ppam
  • .pps
  • .ppsm
  • .ppsm
  • .ppsx
  • .ppt
  • .pptm
  • .pptm
  • .pptx
  • .prf
  • .ps
  • .psafe3
  • .psd
  • .pspimage
  • .pst
  • .ptx
  • .pwm
  • .py
  • .qba
  • .qbb
  • .qbm
  • .qbr
  • .qbw
  • .qbx
  • .qby
  • .qcow
  • .qcow2
  • .qed
  • .qtb
  • .r3d
  • .raf
  • .rar
  • .rat
  • .raw
  • .rdb
  • .rm
  • .rtf
  • .rvt
  • .rw2
  • .rwl
  • .rwz
  • .s3db
  • .safe
  • .sas7bdat
  • .sav
  • .save
  • .say
  • .sd0
  • .sda
  • .sdb
  • .sdf
  • .sh
  • .sldm
  • .sldx
  • .sql
  • .sqlite
  • .sqlite-shm
  • .sqlite-wal
  • .sqlite3
  • .sqlitedb
  • .sr2
  • .srb
  • .srf
  • .srs
  • .srt
  • .srw
  • .st4
  • .st5
  • .st6
  • .st7
  • .st8
  • .stc
  • .std
  • .sti
  • .stm
  • .stw
  • .stx
  • .svg
  • .swf
  • .sxc
  • .sxd
  • .sxg
  • .sxi
  • .sxm
  • .sxw
  • .tar
  • .taz
  • .tbb
  • .tbn
  • .tbz
  • .tex
  • .tga
  • .tgz
  • .thm
  • .tif
  • .tlg
  • .tlx
  • .txt
  • .usr
  • .vbox
  • .vdi
  • .vhd
  • .vhdx
  • .vmdk
  • .vmsd
  • .vmx
  • .vmxf
  • .vob
  • .wab
  • .wad
  • .wallet
  • .war
  • .wav
  • .wb2
  • .wma
  • .wmf
  • .wmv
  • .wpd
  • .wps
  • .x11
  • .x3f
  • .xis
  • .xla
  • .xlam
  • .xlk
  • .xlm
  • .xlr
  • .xls
  • .xlsb
  • .xlsm
  • .xlsx
  • .xlt
  • .xltm
  • .xltx
  • .xlw
  • .xml
  • .ycbcra
  • .yuv
  • .zip

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

  • bin
  • boot
  • dev
  • etc
  • lib
  • lib64
  • proc
  • run
  • sbin
  • srv
  • sys
  • tmp
  • usr
  • var
  • .gem
  • .bundle
  • .nvm
  • .npm

It renames encrypted files using the following names:

  • {random filename}.ecrypt

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

  • {folder of encrypted files}\_DECRYPT_FILE.txt
  • {folder of encrypted files}\_DECRYPT_FILE.html
  • {folder of encrypted files}\index.html

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.470.08
FIRST VSAPI PATTERN DATE: 14 Jun 2017
VSAPI OPR PATTERN File: 13.471.00
VSAPI OPR PATTERN Date: 15 Jun 2017

Step 1

Scan your computer with your Trend Micro product to delete files detected as RANSOM_ELFEREBUS.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.

Step 2

Restore encrypted files from backup.


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