BAT_CRYPTOR.SM01

 Analysis by: Rhena Inocencio

 ALIASES:

BAT/Filecoder.J trojan (ESET)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW


This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

  TECHNICAL DETAILS

File Size:

106,942 bytes

File Type:

BAT

Memory Resident:

No

Initial Samples Received Date:

26 Aug 2014

Payload:

Downloads files, Displays message/message boxes

Arrival Details

This Trojan 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:

  • %User Temp%\keybtccheck.bin
  • %User Temp%\sdel.cmd
  • %User Temp%\KEYBTC.txt
  • %User Temp%\genesis.btc
  • %User Temp%\1024key.btc
  • %Application Data%\KEY.PRIVATE
  • %User Temp%\PRIVATE\KEY{random}.PRIVATE
  • %User Temp%\secring.gpg

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.)

It drops and executes the following files:

  • %User Temp%\sampleautoreplicant.js - accesses sites to download malware components

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It creates the following folders:

  • %User Temp%\PRIVATE

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

Other System Modifications

This Trojan adds the following registry entries:

HKEY_CURRENT_USER\Software\Sysinternals\
SDelete
EulaAccepted = "1"

Download Routine

This Trojan accesses the following websites to download files:

  • http://{BLOCKED}lru.org/images/coherence.btc
  • http://{BLOCKED}lru.org/images/lsass.btc
  • http://{BLOCKED}lru.org/images/spool.btc
  • http://{BLOCKED}lru.org/images/spoolsv.btc
  • http://{BLOCKED}lru.org/images/sv.btc
  • http://{BLOCKED}lru.org/images/tobi.btc
  • http://{BLOCKED}lru.org/images/collapse.btc

It saves the files it downloads using the following names:

  • %User Temp%\coherence.btc
  • %User Temp%\lsass.btc
  • %User Temp%\%User Temp%\spool.btc
  • %User Temp%\spoolsv.btc
  • %User Temp%\sv.btc
  • %User Temp%\tobi.btc
  • %User Temp%\collapse.btc

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

Other Details

This Trojan encrypts files with the following extensions:

  • .xls
  • .xlsx
  • .doc
  • .docx
  • .xlsm
  • .cdr
  • .slddrw
  • .dwg
  • .ai
  • .svg
  • .mdb
  • .1cd
  • .pdf

It renames encrypted files using the following names:

  • {file name and extension}.keybtc@gmail_com

NOTES:

It encrypts files from drives B:\ to Z:\

It renames the following files as follows:

  • %Application Data%\gnupg %Application Data%\gnupg_backup{random number}
  • %User Temp%\day.btc to %User Temp%\iconv.dll
  • %User Temp%\sad.btc to %User Temp%\ sdelete.exe
  • %User Temp%\null.btc to %User Temp%\ taskmgr.exe
  • %User Temp%\secring.gpg.gpg to %User Temp%\ KEY.PRIVATE
  • %User Temp%\lsass.btc to %User Temp%\lsass.exe
  • %User Temp%\coherence.btc to %User Temp%\coherence.exe
  • %User Temp%\spoolsv.btc to %User Temp%\spoolsv.exe
  • %User Temp%\spool.btc to %User Temp%\blat.lib
  • %User Temp%\sv.btc to %User Temp%\blat.dll

It deletes the following folder:

  • %Application Data%\gnupg

This Trojan opens the user's default browser and accesses the following sites to display the ransom note:

  • http://bit.ly/{BLOCKED}ongi
  • http://apps.{BLOCKED}hev.com/2014/08/14/2829

It displays the following ransom note in the opened browser:

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

11.112.01

FIRST VSAPI PATTERN DATE:

26 Aug 2014

VSAPI OPR PATTERN File:

11.113.00

VSAPI OPR PATTERN Date:

27 Aug 2014

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

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\Sysinternals\SDelete
    • EulaAccepted = "1"

Step 4

Search and delete this folder

[ 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.
  • %User Temp%\KEYPRIVATE

Step 5

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.  
  • %User Temp%\keybtccheck.bin
  • %User Temp%\sdel.cmd
  • %User Temp%\KEYBTC.txt
  • %User Temp%\genesis.btc
  • %User Temp%\1024key.btc
  • %Application Data%\KEY.PRIVATE
  • %User Temp%\PRIVATE\KEY{random}.PRIVATE
  • %User Temp%\secring.gpg
  • %User Temp%\sampleautoreplicant.js
  • %User Temp%\iconv.dll
  • %User Temp%\sdelete.exe
  • %User Temp%\taskmgr.exe
  • %User Temp%\KEY.PRIVATE
  • %User Temp%\lsass.exe
  • %User Temp%\coherence.exe
  • %User Temp%\spoolsv.exe
  • %User Temp%\blat.lib
  • %User Temp%\blat.dll
  • %User Temp%\day.btc
  • %User Temp%\sad.btc
  • %User Temp%\null.btc
  • %User Temp%\secring.gpg
  • %User Temp%\lsass.btc
  • %User Temp%\coherence.btc
  • %User Temp%\spoolsv.btc
  • %User Temp%\spool.btc
  • %User Temp%\sv.btc

Step 6

Scan your computer with your Trend Micro product to delete files detected as BAT_CRYPTOR.SM01. 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.


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