RANSOM_CRYPTESLA.YUYAJC


 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:

Downloaded from the Internet, Dropped by other malware

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 modifies the Internet Explorer Zone Settings.

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:

483,328 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

09 Mar 2016

Payload:

Corrupts hard disk, Encrypts files, Connects to URLs/IPs, Steals information

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:

  • %Windows%\{random filename}.exe (with Administrator Privileges)
  • %My Documents%\{random filename}.exe (with non-Administrator Privileges)

    (Note: %My Documents% is C:\Users\{user name}\Documents on Windows Vista and above.)

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

It drops the following files:

  • %My Documents%\recover_file_{random characters}.txt
  • Ransom Notes:
    • %Desktop%\_ReCoVeRy_.HTM
    • %Desktop%\_ReCoVeRy_.png
    • %Desktop%\_ReCoVeRy_.TXT
    • %User Profile%\_ReCoVeRy_+{random characters}.html
    • %User Profile%\_ReCoVeRy_+{random characters}.png
    • %User Profile%\_ReCoVeRy_+{random characters}.txt
    • {Folders containing encrypted files}\_ReCoVeRy_+{random characters}.html
    • {Folders containing encrypted files}\_ReCoVeRy_+{random characters}.png
    • {Folders containing encrypted files}\_ReCoVeRy_+{random characters}.txt

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

Autostart Technique

This Trojan creates the following registry entries to enable automatic execution of dropped component at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{4 random characters}-{8 random characters} = "%Windows%\{random filename}.exe" (with Administrator Privileges)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{4 random characters}-{8 random characters} = "%My Documents%\{random filename}.exe" (with non-Administrator Privileges)

Other System Modifications

This Trojan modifies the following file(s):

  • It encrypts files and appends the extension .mp3 to them

It adds the following registry keys:

HKEY_CURRENT_USER\Software\zzzsys

HKEY_CURRENT_USER\Software\{Installation ID}

It adds the following registry entries as part of its installation routine:

HKEY_CURRENT_USER\Software\zzzsys
ID = {Installation ID}

Web Browser Home Page and Search Page Modification

This Trojan modifies the Internet Explorer Zone Settings.

Other Details

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

  • http://{BLOCKED}edicalcentre.com/wp-content/uploads/wstr.php
  • http://{BLOCKED}lizedaccess.co.uk/wp-content/uploads/2015/09/wstr.php
  • http://{BLOCKED}stitut.org/wp-content/themes/bstr.php
  • http://www.{BLOCKED}aticauno.net/gamma/tmp/bstr.php
  • http://www.{BLOCKED}aticauno.net/gamma/tmp/wstr.php
  • http://{BLOCKED}our.info/users/28c4fe1/wstr.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\zzzsys

NOTES:

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

It executes the following command to delete shadow copies:

"C:\Windows\System32\wbem\WMIC.exe" shadowcopy delete /nointeractive

It opens the following ransom notes after encryption:

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

12.392.09

FIRST VSAPI PATTERN DATE:

09 Mar 2016

VSAPI OPR PATTERN File:

12.393.00

VSAPI OPR PATTERN Date:

10 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.YUYAJC

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
    • {4 random characters}-{8 random characters} = "%Windows%\{random filename}.exe" (with Administrator Privileges)
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {4 random characters}-{8 random characters} = "%My Documents%\{random filename}.exe" (with non-Administrator Privileges)

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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_CURRENT_USER\Software
    • zzzsys
  • In HKEY_CURRENT_USER\Software
    • {Installation ID}

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_CRYPTESLA.YUYAJC. 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 8

Restore encrypted files from backup.


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