Ransom.Win32.CRYPTESLA.B

 Analysis by: Jay Bradley Nebre

 ALIASES:

Ransom:Win32/Tescrypt.H(Microsoft); Trojan.Win32.Shifu.aya(Kaspersky); Trojan-Ransom.TeslaCrypt(Ikarus)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware


This Ransomware 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 gathers information and reports it to its servers.

It encrypts files with specific file extensions.

  TECHNICAL DETAILS

File Size:

478,720 bytes

File Type:

EXE

File Compression:

Aspack

Memory Resident:

Yes

Initial Samples Received Date:

18 Mar 2019

Payload:

Modifies system registry, Collects system information, Connects to URLs/IPs, Steals information

Arrival Details

This Ransomware 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 Ransomware drops the following files:

  • %User Profile%\Documents\recover_file_{9 random letters}.txt
  • Recovery-{5random letters}.png - drops in every folder infected
  • Recovery-{5random letters}.txt - drops in every folder infected
  • Recovery-{5random letters}.html - drops in every folder infected

(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, 7, and 8.)

It drops and executes the following files:

  • %Windows%\{9 random letters}.exe; - copy of unpacked malware
  • %User Profile%\Documents\{5 random letters}.exe - contains delete shadows copies
  • %User Profile%\Documents\{5 random letters}.exe - a copy of the other drop file that deletes shadow copies

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.. %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, 7, and 8.)

It adds the following processes:

  • %System%\cmd.exe /c DEL {malware path\name}.exe;
  • %System%\vssadmin.exe delete shadows /all /Quiet
  • %System%\NOTEPAD.EXE %Desktop%\RECOVERY.TXT;

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.. %Desktop% is the current user's desktop, which is usually C:\Documents and Settings\{User Name}\Desktop on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\Desktop on Windows Vista, 7, and 8.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
v23-deadbeef = %Windows%\{9 random characters}.exe

Other System Modifications

This Ransomware adds the following registry keys:

HKEY_CURRENT_USER\Software\xxxsys
ID = {hex value}

HKEY_CURRENT_USER\Software\{installation id}
data = {hex value}

Process Termination

This Ransomware terminates processes or services that contain any of the following strings if found running in the affected system's memory:

  • askmg
  • rocex
  • egedi
  • sconfi
  • cmd

Other Details

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

  • http://{BLOCKED}t.ac.in/webcontrol/images/mzsys.php
  • http://{BLOCKED}ro.org/images/icons/mzsys.php
  • http://{BLOCKED}ationalists.org/mzsys.php
  • http://{BLOCKED}c.org.in/wp-content/uploads/mzsys.php
  • http://{BLOCKED}sa.com/wp-content/upgrade/mzsys.php

It opens the following files:

  • %Desktop%RECOVERY.HTM
  • %Desktop%RECOVERY.TXT
  • %Desktop%RECOVERY.PNG

It sets the attributes of the following file(s) to Hidden and System:

  • {drop copy of unpacked self}

It does the following:

  • Avoid encrypting files that have a size of
    • lower than 32bytes
    • greater than 312MB

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

  • Infection Status
  • Bitcoin Address
  • Total size of encrypted files
  • Malware Version
  • OS Information
  • Installation ID

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .r3d
  • .ptx
  • .pef
  • .srw
  • .x3f
  • .der
  • .cer
  • .crt
  • .pem
  • .odt
  • .ods
  • .odp
  • .odm
  • .odc
  • .odb
  • .doc
  • .docx
  • .kdc
  • .mef
  • .mrwref
  • .nrw
  • .orf
  • .raw
  • .rwl
  • .rw2
  • .mdf
  • .dbf
  • .psd
  • .pdd
  • .pdf
  • .eps
  • .jpg
  • .jpe
  • .dng
  • .3fr
  • .arw
  • .srf
  • .sr2
  • .bay
  • .crw
  • .cr2
  • .dcr
  • .ai
  • .indd
  • .cdr
  • .erf
  • .bar
  • .hkx
  • .raf
  • .rofl
  • .dba
  • .db0
  • .kdb
  • .mpqge
  • .vfs0
  • .mcmeta
  • .m2
  • .lrf
  • .vpp_pc
  • .ff
  • .cfr
  • .snx
  • .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
  • .kf
  • .mlx
  • .fpk
  • .dazip
  • .vtf
  • .vcf
  • .esm
  • .blob
  • .dmp
  • .layout
  • .menu
  • .ncf
  • .sid
  • .sis
  • .ztmp
  • .vdf
  • .mov
  • .fos
  • .sb
  • .itm
  • .wmo
  • .itm
  • .map
  • .wmo
  • .sb
  • .svg
  • .cas
  • .gho
  • .syncdb
  • .mdbackup
  • .hkdb
  • .hplg
  • .hvpl
  • .icxs
  • .docm
  • .wps
  • .xls
  • .xlsx
  • .xlsm
  • .xlsb
  • .xlk
  • .ppt
  • .pptx
  • .pptm
  • .mdb
  • .accdb
  • .pst
  • .dwg
  • .xf
  • .dxg
  • .wpd
  • .rtf
  • .wb2
  • .pfx
  • .p12
  • .p7b
  • .p7c
  • .txt
  • .jpeg
  • .png
  • .rb
  • .css
  • .js
  • .flv
  • .m3u
  • .py
  • .desc
  • .xxx
  • .wotreplay
  • wallet
  • .big
  • .pak
  • .rgss3a
  • .epk
  • .bik
  • .slm
  • .lbf
  • .sav
  • .re4
  • .apk
  • .bsa
  • .ltx
  • .forge
  • .asset
  • .litemod
  • .iwi
  • .das
  • .upk
  • .d3dbsp
  • .csv
  • .wmv
  • .avi
  • .wma
  • .m4a
  • .rar
  • .7z
  • .mp4
  • .sql

It avoids encrypting files with the following strings in their file name:

  • ecove
  • .mp3

It avoids encrypting files found in the following folders:

  • %Windows%
  • %Program Files%
  • %ProgramData%

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), 7 (32-bit), and 8 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), 7 (64-bit), and 8 (64-bit).. %ProgramData% is a version of the Program Files folder where any user on a multi-user computer can make changes to programs. This contains application data for all users. This is usually C:\ProgramData in Windows Vista, 7, and 8.)

It appends the following extension to the file name of the encrypted files:

  • .mp3

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.878.07

FIRST VSAPI PATTERN DATE:

18 Mar 2019

VSAPI OPR PATTERN File:

14.879.00

VSAPI OPR PATTERN Date:

19 Mar 2019

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 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

Restart in Safe Mode

[ Learn More ]

Step 4

Identify and terminate files detected as Ransom.Win32.CRYPTESLA.B

[ 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 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
    • v23-deadbeef = %Windows%\{name of drop copy}.exe;

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.

  • HKEY_CURRENT_USER\Software\xxxsys
  • HKEY_CURRENT_USER\Software\{installation id}

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.
  • %Windows%\{9 random letters}.exe
  • %User Profile%\Documents\{5 random letters}.exe
  • %User Profile%\Documents\{5 random letters}.exe
  • %Documents\recover_file_{9 random letters}.txt
  • Recovery-{5random letters}.png - find all in encrypted folders
  • Recovery-{5random letters}.txt - find all in encrypted folders
  • Recovery-{5random letters}.html - find all in encrypted folders
  • %Desktop%\RECOVERY.HTM
  • %Desktop%\RECOVERY.TXT
  • %Desktop%\RECOVERY.PNG

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win32.CRYPTESLA.B. 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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