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RANSOM_ELFACRYPT.A

June 25, 2016
 Analysis by: Jennifer Gumban
 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Spammed via email, Downloaded from the Internet, Dropped by other malware


This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It adds certain registry entries to disable the Task Manager. This action prevents users from terminating the malware process, which can usually be done via the Task Manager.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

72,201 bytes

Memory Resident:

Yes

Payload:

Drops files, Encrypts files

Arrival Details

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

It 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 Trojan drops the following files:

  • {folders containing encrypted files}\Read Me (How Decrypt) !!!!.txt

It drops the following copies of itself into the affected system:

  • %Application Data%\Windows\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 leaves text files that serve as ransom notes containing the following:

  • Greetings, We'd like to apologize for the inconveniences, however, your computer has been locked. In order to unlock it, you have to complete the following steps: 1. Buy iTunes Gift Cards for a total amount of $400.00 2. Send the gift codes to the indicated e-mail address 3. Receive a code and a file that will unlock your computer. Please note:, - The nominal amount of the particular gift card doesn't matter, yet the total amount have to be as listed above. - You can buy the iTunes Gift Cards online or in any shop. The codes must be correct, otherwise, you won't receive anything. - After receiving the code and the security file, your computer will be unlocked and will never be locked again. Sorry for the inconveniences caused.

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Microsoft = %Application Data%\Windows\svchost.exe

Other System Modifications

This Trojan adds the following registry entries to disable the Task Manager:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableTaskMgr = "1"

Other Details

This Trojan encrypts files with the following extensions:

  • .3ds
  • .3fr
  • .3pr
  • .ab4
  • .ac2
  • .accdb
  • .accde
  • .accdr
  • .accdt
  • .acr
  • .adb
  • .agd1
  • .ai
  • .ait
  • .al
  • .apj
  • .arw
  • .asm
  • .asp
  • .aspx
  • .awg
  • .backup
  • .backupdb
  • .bak
  • .bat
  • .bdb
  • .bgt
  • .bik
  • .bkp
  • .blend
  • .bmp
  • .bpw
  • .c
  • .c
  • .cdf
  • .cdr
  • .cdr3
  • .cdr4
  • .cdr5
  • .cdr6
  • .cdrw
  • .cdx
  • .ce1
  • .ce2
  • .cer
  • .cfp
  • .cgm
  • .cib
  • .class
  • .cls
  • .cmd
  • .cmt
  • .cpi
  • .cpp
  • .cr2
  • .craw
  • .crt
  • .crw
  • .cs
  • .csh
  • .csl
  • .css
  • .csv
  • .dac
  • .db
  • .db3
  • .dbf
  • .db-journal
  • .dc2
  • .dcr
  • .dcs
  • .ddd
  • .ddoc
  • .ddrw
  • .der
  • .design
  • .dgc
  • .djvu
  • .dng
  • .doc
  • .docm
  • .docx
  • .dot
  • .dotm
  • .dotx
  • .drf
  • .drw
  • .dwg
  • .dxb
  • .erbsql
  • .erf
  • .exf
  • .fdb
  • .ffd
  • .fff
  • .fh
  • .fhd
  • .fpx
  • .fxg
  • .gif
  • .gray
  • .grey
  • .gry
  • .h
  • .h
  • .hbk
  • .hpp
  • .html
  • .ibank
  • .ibd
  • .ibz
  • .idx
  • .iiq
  • .incpas
  • .jar
  • .java
  • .jpeg
  • .jpg
  • .js
  • .kc2
  • .kdbx
  • .kdc
  • .kpdx
  • .lua
  • .mdb
  • .mdc
  • .mef
  • .mfw
  • .mmw
  • .moneywell
  • .mos
  • .mpg
  • .mrw
  • .myd
  • .ndd
  • .nef
  • .nop
  • .nrw
  • .ns2
  • .ns3
  • .ns4
  • .nsd
  • .nsf
  • .nsg
  • .nsh
  • .nwb
  • .nx1
  • .nx2
  • .nyf
  • .odb
  • .odf
  • .odg
  • .odm
  • .odp
  • .ods
  • .odt
  • .orf
  • .otg
  • .oth
  • .otp
  • .ots
  • .ott
  • .p12
  • .p7b
  • .p7c
  • .pat
  • .pcd
  • .pdf
  • .pef
  • .pem
  • .pfx
  • .php
  • .pl
  • .png
  • .pot
  • .potm
  • .potx
  • .ppam
  • .pps
  • .ppsm
  • .ppsx
  • .ppt
  • .pptm
  • .pptx
  • .ps
  • .psafe3
  • .psd
  • .ptx
  • .py
  • .ra2
  • .raf
  • .raw
  • .rdb
  • .rtf
  • .rw2
  • .rwl
  • .rwz
  • .s3db
  • .sas7bdat
  • .sav
  • .sd0
  • .sd1
  • .sda
  • .sdf
  • .sldm
  • .sldx
  • .sln
  • .sql
  • .sqlite
  • .sqlite3
  • .sqlitedb
  • .sr2
  • .srf
  • .srw
  • .st4
  • .st5
  • .st6
  • .st7
  • .st8
  • .stc
  • .std
  • .sti
  • .stw
  • .stx
  • .svg
  • .sxc
  • .sxd
  • .sxg
  • .sxi
  • .sxm
  • .sxw
  • .txt
  • .vb .vbs
  • .wb2
  • .x3f
  • .xla
  • .xlam
  • .xll
  • .xlm
  • .xls
  • .xlsb
  • .xlsm
  • .xlsx
  • .xlt
  • .xltm
  • .xltx
  • .xlw
  • .xml
  • .ycbcra

It renames encrypted files using the following names:

  • {original file name and extension}.encrypt

It does the following:

  • It encrypts files in the ff folders:
    • Desktop
    • Programs
    • Personal
    • MyDocuments
    • Favorites
    • Startup
    • Recent
    • SendTo
    • StartMenu
    • MyMusic
    • DesktopDirectory
    • MyComputer
    • Templates
    • ApplicationData
    • LocalApplicationData
    • InternetCache
    • Cookies
    • History
    • CommonApplicationData
    • System
    • ProgramFiles
    • MyPictures
    • CommonProgramFiles

It deletes itself after execution.

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

12.546.08

FIRST VSAPI PATTERN DATE:

24 May 2016

VSAPI OPR PATTERN File:

12.547.00

VSAPI OPR PATTERN Date:

25 May 2016

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

Search and delete this file

[ 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. DATA_GENERIC
  • In the Look In drop-down list, select My Computer then press Enter.
  • Once located, select the file then press SHIFT+DELETE to delete it.
    *Note: The file name input box title varies depending on the Windows version (e.g. Search for files or folders named or All or part of the file name.).

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

    1. Open a Windows Explorer window.
      • For Windows Vista, 7, and Server 2008 users, click Start>Computer.
      • For Windows 8, 8.1, and Server 2012 users, right-click on the lower left corner of the screen, then click File Explorer.
    2. In the Search Computer/This PC input box, type:
      DATA_GENERIC
    3. Once located, select the file then press SHIFT+DELETE to delete it.
      *Note: Read the following Microsoft page if these steps do not work on Windows 7.

    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
      • Microsoft = "%Application Data%\Windows\svchost.exe"
    • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System
      • DisableTaskMgr = "1"

    Step 5

    Scan your computer with your Trend Micro product to delete files detected as RANSOM_ELFACRYPT.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 6

    Restore encrypted files from backup.


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