Analysis by: Rhena Inocencio
ALIASES:

Ransomware-FHE!E7E2891F1584 (McAfee), Mal/Ransom-EM (Sophos)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet

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.

It connects to certain websites to send and receive information. It deletes the initially executed copy of itself. It gathers information and reports it to its servers.

  TECHNICAL DETAILS

File Size: 192,512 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 02 Apr 2016
Payload: Connects to URLs/IPs, Encrypts files, Displays graphics/image

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 copies of itself into the affected system and executes them:

  • %My Documents%\{random filename}.exe

    (Note: %My Documents% is usually C:\Documents and Settings\{user name}\My Documents on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\Documents on Windows Vista and 7.)

It drops the following files:

  • {folders containing encrypted files}\+-HELP-RECOVER-+{random 5 characters}-+.html
  • {folders containing encrypted files}\+-HELP-RECOVER-+{random 5 characters}-+.png
  • {folders containing encrypted files}\+-HELP-RECOVER-+{random 5 characters}-+.txt
  • %Desktop%\+-HELP-RECOVER-+{random 5 characters}-+.html
  • %Desktop%\+-HELP-RECOVER-+{random 5 characters}-+.png
  • %Desktop%\+-HELP-RECOVER-+{random 5 characters}-+.txt
  • %My Documents%\+recover+file.txt

(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.)

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
+++{random characters} = "%System%\cmd.exe /c start %My Documents%\{random filename}.exe"

Other System Modifications

This Trojan adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
system
EnableLinkedConnections = "1"

HKEY_CURRENT_USER\Software\trueimg
ID = "{ID}"

It modifies the following registry key(s)/entry(ies) as part of its installation routine:

HKEY_CURRENT_USER\Software\trueimg

HKEY_CURRENT_USER\Software\{ID}

Other Details

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

  • http://{BLOCKED}ia.com/sysstr.php
  • http://{BLOCKED}2k15.in/sysstr.php
  • http://{BLOCKED}y.org/sysstr.php
  • http://{BLOCKED}l.com/sysstr.php
  • http://{BLOCKED}sports.info/sysstr.php
  • http://{BLOCKED}legue.com/sysstr.php

It encrypts files with the following extensions:

  • .lvl
  • .arch00
  • .ntl
  • .fsh
  • .itdb
  • .itl
  • .mddata
  • .sidd
  • .sidn
  • .bkf
  • .qic
  • .bkp
  • .bc7
  • .bc6
  • .pkpass
  • .tax
  • .gdb
  • .qdf
  • .t12
  • .t13
  • .ibank
  • .sum
  • .sie
  • .zip
  • .w3x
  • .rim
  • .psk
  • .tor
  • .vpk
  • .iwd
  • .mlx
  • .fpk
  • .dazip
  • .vtf
  • .vcf
  • .esm
  • .blob
  • .dmp
  • .layout
  • .menu
  • .kf
  • .ncf
  • .sid
  • .sis
  • .ztmp
  • .vdf
  • .mov
  • .fos
  • .itm
  • .wmo
  • .itm
  • .map
  • .wmo
  • .svg
  • .cas
  • .gho
  • .syncdb
  • .hkdb
  • .hplg
  • .hvpl
  • .icxs
  • .docm
  • .wps
  • .xls
  • .xlsx
  • .xlsm
  • .xlsb
  • .xlk
  • .ppt
  • .pptx
  • .pptm
  • .mdb
  • .accdb
  • .pst
  • .dwg
  • .dxg
  • .wpd
  • .rtf
  • .wb2
  • .pfx
  • .p12
  • .p7b
  • .sb
  • .mdbackup
  • .xf
  • .p7c
  • .txt
  • .jpeg
  • .png
  • .css
  • .flv
  • .m3u
  • .desc
  • .xxx
  • wallet
  • .big
  • .pak
  • .rgss3a
  • .epk
  • .bik
  • .slm
  • .lbf
  • .sav
  • .re4
  • .apk
  • .bsa
  • .ltx
  • .forge
  • .asset
  • .iwi
  • .das
  • .upk
  • .d3dbsp
  • .csv
  • .wmv
  • .avi
  • .wma
  • .m4a
  • .rar
  • .mp4
  • .sql
  • .bak
  • .tiff
  • .com
  • .py
  • .js
  • .rb
  • .litesql
  • .litemod
  • .7z
  • .x3f
  • .der
  • .cer
  • .crt
  • .pem
  • .odt
  • .ods
  • .odp
  • .odm
  • .odc
  • .odb
  • .doc
  • .docx

It deletes the initially executed copy of itself

It gathers the following information and reports it to its servers:

  • IP address
  • OS version
  • installation id (inst_id)
  • ID value from the registry HKEY_CURRENT_USER\Software\trueimg

NOTES:

This malware does not append an extension to the encrypted files.

It encrypts files in all fixed, removable, and network drives and shares.

It executes the following command to delete shadow copies:

vssadmin.exe Delete Shadows /All /Quiet

It opens the following ransom notes after encryption:

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 12.418.07
FIRST VSAPI PATTERN DATE: 22 Mar 2016
VSAPI OPR PATTERN File: 12.419.00
VSAPI OPR PATTERN Date: 23 Mar 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

Scan your computer with your Trend Micro product and note files detected as RANSOM_CRYPTESLA.YUYAJY

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

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
    • +++{random characters} = "%System%\cmd.exe /c start %My Documents%\{random filename}.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\system
    • EnableLinkedConnections = "1"

Step 6

Delete this registry key

[ 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
    • {ID}
  • In HKEY_CURRENT_USER\Software
    • trueimg

Step 7

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.
  • +-HELP-RECOVER-+{random 5 characters}-+.html
  • +-HELP-RECOVER-+{random 5 characters}-+.png
  • +-HELP-RECOVER-+{random 5 characters}-+.txt
  • %My Documents%\+recover+file.txt

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_CRYPTESLA.YUYAJY. 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 9

Restore encrypted files from backup.


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