RANSOM_EXTRACTOR.B

July 09, 2018
 Analysis by: Kiyoshi Obuchi
 ALIASES:

a variant of Win32/Filecoder.CJ trojan (NOD32); Trojan.GenericKD.4970845 (BitDefender))

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: Yes

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet

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

  TECHNICAL DETAILS

File Size:

1001704 bytes

File Type:

EXE

Initial Samples Received Date:

02 Jul 2018

Payload:

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.

Autostart Technique

This Ransomware modifies the following registry entry(ies) to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
Explorer\Run
System = "{MALWARE PATH}\{MALWARE NAME}.exe"

Other Details

This Ransomware does the following:

  • The following commands are executed to stop services:
    • %System%\net1 STOP IISADMIN /Y -> stops ISSADMIN
    • %System%\net1 STOP MSEXCHANGEADTOPOLOGY /Y -> stops MSEXCHANGEADTOPOLOGY
    • %System%\net1 STOP MSEXCHANGEIS /Y -> stops MSEXCHANGEIS
    • %System%\net1 STOP MSEXCHANGESA /Y -> stops MSEXCHANGESA
    • %System%\net1 STOP MSFTESQL-EXCHANGE /Y -> stops MSFTESQL-EXCHANGE
    • %System%\net1 STOP MSSQLSERVER /Y -> stops MSSQLSERVER
    • %System%\net1 STOP SQLSERVERAGENT /Y -> stops SQLSERVERAGENT
    • %System%\sc.exe CONFIG "IISADMIN" START= DISABLED -> stops ISSADMIN
    • %System%\sc.exe CONFIG "MSEXCHANGEADTOPOLOGY" START= DISABLED -> stops MSEXCHANGEADTOPOLOGY
    • %System%\sc.exe CONFIG "MSEXCHANGEIS" START= DISABLED -> stops MSEXCHANGEIS
    • %System%\sc.exe CONFIG "MSEXCHANGESA " START= DISABLED -> stops MSEXCHANGESA
    • %System%\sc.exe CONFIG "MSFTESQL-EXCHANGE" START= DISABLED -> stops MSFTESQL-EXCHANGE
    • %System%\sc.exe CONFIG "MSSQLSERVER" START= DISABLED -> stops MSSQLSERVER
    • %System%\sc.exe CONFIG "SQLSERVERAGENT" START= DISABLED -> stops ISSADMIN
  • The following command creates the scheduled task:
    • %System%\schtasks.exe /CREATE /TN "System Update" /TR "{Malware Directory}\{Malware Filename}.exe" /SC ONSTART /RL HIGHEST /RU "System"

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

It adds the following scheduled tasks:

    • TaskName: System Update
    • Triggers: ON STARTUP
    • Executes: {MALWARE PATH}\{MALWARE NAME}.exe

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • ._lg
  • ._ms
  • .3fr
  • .4db
  • .4dd
  • .4dl
  • .4mp
  • .7z
  • .7z
  • .abs
  • .accdb
  • .accdc
  • .accde
  • .accdr
  • .accdt
  • .accdu
  • .accdw
  • .accft
  • .ace
  • .ade
  • .adp
  • .aft
  • .ahd
  • .ai
  • .alf
  • .alz
  • .arc
  • .arj
  • .arw
  • .ask
  • .asp
  • .aspx
  • .awdb
  • .azz
  • .backup
  • .bak
  • .bay
  • .bdb
  • .bib
  • .bkf
  • .bnd
  • .bok
  • .btr
  • .bz
  • .bz
  • .bz2
  • .bz2
  • .cab
  • .caj
  • .cat
  • .cdb
  • .cdr
  • .cdx
  • .cer
  • .ckz
  • .clkw
  • .conf
  • .cpio
  • .cpp
  • .cr2
  • .crd
  • .crt
  • .crw
  • .ctf
  • .cur
  • .daf
  • .dat
  • .db
  • .db2
  • .db3
  • .db5
  • .dbc
  • .dbf
  • .db-journal
  • .dbk
  • .dbs
  • .dbt
  • .dbv
  • .dbx
  • .dcr
  • .dct
  • .dcx
  • .deb
  • .deploy
  • .der
  • .df1
  • .dmg
  • .dmo
  • .dnc
  • .dng
  • .doc
  • .docm
  • .docx
  • .dp1
  • .dqy
  • .dsk
  • .dsn
  • .dta
  • .dtsx
  • .dwg
  • .dxf
  • .dxl
  • .eco
  • .ecx
  • .edb
  • .emd
  • .emf
  • .eml
  • .eql
  • .erf
  • .fcd
  • .fdb
  • .fic
  • .fid
  • .fil
  • .fm5
  • .fmp
  • .fods
  • .fodt
  • .fol
  • .fp3
  • .fp4
  • .fp5
  • .fp7
  • .fpt
  • .fzb
  • .fzv
  • .gdb
  • .gho
  • .ghs
  • .gif
  • .gwi
  • .gz
  • .gz
  • .hdb
  • .his
  • .ib
  • .ibd
  • .idc
  • .ihx
  • .ii
  • .img
  • .indd
  • .iso
  • .itdb
  • .itw
  • .ix
  • .jar
  • .jpe
  • .jpg
  • .jtx
  • .kdb
  • .kdc
  • .lck
  • .ldf
  • .lgc
  • .lha
  • .log
  • .lz
  • .lzma
  • .lzo
  • .lzo
  • .maq
  • .mar
  • .marshal
  • .mas
  • .mav
  • .maw
  • .mdb
  • .mdbhtml
  • .mdf
  • .mdn
  • .mdt
  • .mef
  • .mf
  • .mod
  • .mox
  • .mp4
  • .mud
  • .mwb
  • .myd
  • .nbf
  • .ndf
  • .nef
  • .nrw
  • .ns2
  • .ns3
  • .ns4
  • .nsf
  • .nyf
  • .oce
  • .odb
  • .odc
  • .odm
  • .odp
  • .ods
  • .odt
  • .opts
  • .oqy
  • .ora
  • .orf
  • .orx
  • .out
  • .owc
  • .owg
  • .oyx
  • .p12
  • .p7b
  • .p7c
  • .p96
  • .p97
  • .pan
  • .par
  • .pdb
  • .pdd
  • .pdf
  • .pdm
  • .pef
  • .pfx
  • .phm
  • .php
  • .pid
  • .pkz
  • .png
  • .pnz
  • .pptm
  • .pptx
  • .psd
  • .pst
  • .pth
  • .ptx
  • .pwa
  • .qf1
  • .qpx
  • .qvd
  • .raf
  • .rar
  • .raw
  • .rdb
  • .rpd
  • .rpm
  • .rsa
  • .rsd
  • .rtf
  • .rw2
  • .rwl
  • .rwm
  • .rz
  • .sbf
  • .scx
  • .sdb
  • .sdf
  • .sf
  • .spq
  • .sqb
  • .sql
  • .sqlite
  • .sqlite3
  • .sqlitedb
  • .srf
  • .srw
  • .stm
  • .str
  • .sxdat
  • .sxhli
  • .sxptz
  • .tar
  • .tar
  • .tar
  • .tar
  • .tar
  • .tar
  • .tar
  • .tar
  • .tbz
  • .tbz2
  • .tcx
  • .tdt
  • .te
  • .teacher
  • .tgz
  • .tib
  • .tmd
  • .trc
  • .txt
  • .tz
  • .tzo
  • .udb
  • .udl
  • .usr
  • .v12
  • .vdb
  • .vhd
  • .vsx
  • .wb2
  • .wdb
  • .wmdb
  • .wmf
  • .wpd
  • .wps
  • .wrx
  • .x3f
  • .xdb
  • .xg3
  • .xgo
  • .xld
  • .xlgc
  • .xlk
  • .xls
  • .xlsb
  • .xlsm
  • .xlsx
  • .xml
  • .xz
  • .xz
  • .z
  • .z
  • .zdb
  • .zdc
  • .zip
  • .zpd

It avoids encrypting files found in the following folders:

  • %Windows%

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)

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

  • .xxx

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

  • {Encrypted Drive}\ReadMe_XXX.txt

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.354.05

FIRST VSAPI PATTERN DATE:

02 Jul 2018

VSAPI OPR PATTERN File:

14.355.00

VSAPI OPR PATTERN Date:

03 Jul 2018

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

Identify and terminate files detected as RANSOM_EXTRACTOR.B

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Explorer\Run
    • System = "{MALWARE PATH}\{MALWARE NAME}.exe"

Step 5

Deleting Scheduled Tasks

The following {Task Name} - {Task to be run} listed should be used in the steps identified below:

  • System Update - {MALWARE PATH}\{MALWARE NAME}.exe

For Windows 2000, Windows XP, and Windows Server 2003:

  1. Open the Windows Scheduled Tasks. Click Start>Programs>Accessories>
    System Tools>Scheduled Tasks.
  2. Locate each {Task Name} values listed above in the Name column.
  3. Right-click on the said file(s) with the aforementioned value.
  4. Click on Properties. In the Run field, check for the listed {Task to be run}.
  5. If the strings match the list above, delete the task.

For Windows Vista, Windows 7, Windows Server 2008, Windows 8, Windows 8.1, and Windows Server 2012:

  1. Open the Windows Task Scheduler. To do this:
    • On Windows Vista, Windows 7, and Windows Server 2008, click Start, type taskschd.msc in the Search input field, then press Enter.
    • On Windows 8, Windows 8.1, and Windows Server 2012, right-click on the lower left corner of the screen, click Run, type taskschd.msc, then press Enter.
  2. In the left panel, click Task Scheduler Library.
  3. In the upper-middle panel, locate each {Task Name} values listed above in the Name column.
  4. In the lower-middle panel, click the Actions tab. In the Details column, check for the {Task to be run} string.
  5. If the said string is found, delete the task.

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.
  • D:\ReadMe_XXX.txt
  • F:\ReadMe_XXX.txt

Step 7

Scan your computer with your Trend Micro product to delete files detected as RANSOM_EXTRACTOR.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 8

Restore encrypted files from backup.

NOTES:

To restart the service open command prompt and execute the following commands:

  • net1 START IISADMIN /Y
  • net1 START MSEXCHANGEADTOPOLOGY /Y
  • net1 START MSEXCHANGEIS /Y
  • net1 START MSEXCHANGESA /Y
  • net1 START MSFTESQL-EXCHANGE /Y
  • net1 START MSSQLSERVER /Y
  • net1 START SQLSERVERAGENT /Y


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