Analysis by: Rhena Inocencio
ALIASES:

Trojan.Ransomcrypt.BA (Symantec), Ransom-O (McAfee), Win32/Filecoder.Bart.A (ESET)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Dropped by other malware

This Trojan may be downloaded by other malware/grayware/spyware from remote sites.

This is the Trend Micro detection for files that exhibit certain behaviors.

  TECHNICAL DETAILS

File Size: 350,208 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 27 Jun 2016
Payload: Displays message/message boxes, Encrypts files

Arrival Details

This Trojan may be downloaded by other malware/grayware/spyware from remote sites.

Installation

This Trojan drops the following files:

  • %Desktop%\recover.bmp - image used as wallpaper
  • %Desktop%\recover.txt - contains the ransom note
  • {folders containing the archived files}\recover.txt - contains the ransom note

(Note: %Desktop% is the desktop folder, where it usually is C:\Documents and Settings\{user name}\Desktop in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\Desktop in 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.)

Other System Modifications

This Trojan modifies the following file(s):

  • It archives the files into a password protected ZIP and names the archive as {original filename and extension}.bart.zip

It changes the desktop wallpaper by modifying the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = "%Desktop%\recover.bmp"

(Note: The default value data of the said registry entry is {user-defined}.)

It sets the system's desktop wallpaper to the following image:

Other Details

This Trojan encrypts files with the following extensions:

  • .mid
  • .wma
  • .flv
  • .mkv
  • .mov
  • .avi
  • .asf
  • .mpeg
  • .vob
  • .mpg
  • .wmv
  • .fla
  • .swf
  • .wav
  • .qcow2
  • .vdi
  • .vmdk
  • .vmx
  • .gpg
  • .aes
  • .ARC
  • .PAQ
  • .tar
  • .bz2
  • .tbk
  • .bak
  • .tar
  • .tgz
  • .rar
  • .zip
  • .djv
  • .djvu
  • .svg
  • .bmp
  • .png
  • .gif
  • .raw
  • .cgm
  • .jpeg
  • .jpg
  • .tif
  • .tiff
  • .NEF
  • .psd
  • .cmd
  • .bat
  • .class
  • .jar
  • .java
  • .asp
  • .brd
  • .sch
  • .dch
  • .dip
  • .vbs
  • .asm
  • .pas
  • .cpp
  • .php
  • .ldf
  • .mdf
  • .ibd
  • .MYI
  • .MYD
  • .frm
  • .odb
  • .dbf
  • .mdb
  • .SQLITEDB
  • .SQLITE3
  • .asc
  • .lay6
  • .lay
  • .ms11(Security copy)
  • .sldm
  • .sldx
  • .ppsm
  • .ppsx
  • .ppam
  • .docb
  • .sxm
  • .otg
  • .odg
  • .uop
  • .potx
  • .potm
  • .pptx
  • .pptm
  • .std
  • .sxd
  • .pot
  • .pps
  • .sti
  • .sxi
  • .otp
  • .odp
  • .wks
  • .xltx
  • .xltm
  • .xlsx
  • .xlsm
  • .xlsb
  • .slk
  • .xlw
  • .xlt
  • .xlm
  • .xlc
  • .dif
  • .stc
  • .sxc
  • .ots
  • .ods
  • .hwp
  • .dotm
  • .dotx
  • .docm
  • .docx
  • .DOT
  • .max
  • .txt
  • .CSV
  • .uot
  • .RTF
  • .pdf
  • .XLS
  • .PPT
  • .stw
  • .sxw
  • .ott
  • .odt
  • .DOC
  • .pem
  • .csr
  • .crt
  • .key

This is the Trend Micro detection for:

  • Bart Ransomware

It does the following:

  • It does not encrypt files in locations having the following strings:
    • tmp
    • winnt
    • Application Data
    • AppData
    • PerfLogs
    • Program Files (x86)
    • Program Files
    • ProgramData
    • temp
    • Recovery
    • $Recycle.Bin
    • System Volume Information
    • Boot
    • Windows

NOTES:

The dropped recover.txt contains the ransom note and instructions how to pay:

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 12.618.06
FIRST VSAPI PATTERN DATE: 28 Jun 2016
VSAPI OPR PATTERN File: 12.619.00
VSAPI OPR PATTERN Date: 29 Jun 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

Identify and terminate files detected as RANSOM_BARTZ.A

[ 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

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.
  • %Desktop%\recover.bmp
  • %Desktop%\recover.txt
  • {folders containing the archived files}\recover.txt

Step 5

Reset your Desktop properties

[ Learn More ]

Step 6

Scan your computer with your Trend Micro product to delete files detected as RANSOM_BARTZ.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 7

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • user's files archived by this ransomware


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