Ransom.Win32.EGREGOR.A

 Analysis by: Bren Matthew Ebriega

 ALIASES:

Ransom:Win32/EregorCrypt.G!MSR (MICROSOFT); W32/Kryptik.HGHT!tr (FORTINET)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware, Downloaded from the Internet


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 drops files as ransom note. It avoids encrypting files with the following file extensions.

  TECHNICAL DETAILS

File Size:

806,912 bytes

File Type:

DLL

Memory Resident:

Yes

Initial Samples Received Date:

08 Oct 2020

Payload:

Steals information, Drops files, Terminates processes, Encrypts files

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:

  • %Program Data%\dtb.dat → Contains machine generated RSA public key and encrypted RSA key.
  • {Encrypted Directory}\{CRC32 of Netbios Domain Name}.lnk → Deleted afterwards

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • Global\{Volume Serial Number + CRC32 Hash of Computer name}

Process Termination

This Ransomware terminates the following services if found on the affected system:

  • Services that contain the string:
    • sql
    • database
  • If --killRDP is enabled:
    • TermService
    • Teamviewer

It terminates the following processes if found running in the affected system's memory:

  • agntsvc.exe
  • dbeng50.exe
  • dbsnmp.exe
  • dumpcap.exe
  • encsvc.exe
  • excel.exe
  • firefoxconfig.exe
  • infopath.exe
  • ipython.exe
  • isqlplussvc.exe
  • msaccess.exe
  • msftesql.exe
  • mspub.exe
  • mydesktopqos.exe
  • mydesktopservice.exe
  • mysqld-nt.exe
  • mysqld-opt.exe
  • mysqld.exe
  • ocautoupds.exe
  • ocomm.exe
  • ocssd.exe
  • onenote.exe
  • oracle.exe
  • outlook.exe
  • powerpnt.exe
  • procexp.exe
  • procexp64.exe
  • procmon.exe
  • procmon64.exe
  • python.exe
  • QBW32.exe
  • QBW64.exe
  • sqbcoreservice.exe
  • sqlagent.exe
  • sqlbrowser.exe
  • sqlservr.exe
  • sqlwriter.exe
  • steam.exe
  • synctime.exe
  • tbirdconfig.exe
  • thebat.exe
  • thebat64.exe
  • thunderbird.exe
  • visio.exe
  • winword.exe
  • wordpad.exe
  • wpython.exe
  • xfssvccon.exe

Information Theft

This Ransomware gathers the following data:

  • Computer Name
  • User Name
  • NetBios Domain Name
  • Operating System Version
  • Drive Information (Drive Type and Available Disk Space)
  • Antivirus Product Installed
  • Volume Serial Number

Other Details

This Ransomware does the following:

  • It requires the argument -pass2police in order for it to continue with its ransomware routine
  • It is capable of accepting the following arguments:
    • --nop → Exit the malware without performing its routines
    • --greetings="{string}" → Set greetings in ransom note.
    • --append="{string}" → Set extension to append on encrypted files.
    • --path="{Folder Path}" → Specify path to only encrypt.
    • --norename → Does not append extension to encrypted files
    • --nonet → Do not encrypt network drives
    • --full → Encrypt both local and network drives
    • --target="{string}" → Target file extension to encrypt. (Will avoid files with other extension but will still encrypt files without extension)
    • --killrdp → Terminates Specified Services. Disable RDP
    • --samba → Created LNK files will not have "DELETE_ON_CLOSE" attribute
    • --multiproc → Avoid creating Mutex (to allow multiple instance of malware)
    • --fast="{size in MB}" → Specify file size limit for encryption in MB.
    • --nomimikatz
  • It checks for the computer's language and terminates itself if any the following language is detected:
    • Armenian
    • Azerbaijani
    • Azeri
    • Belarusian
    • Georgian
    • Kazakh
    • Kyrgyz
    • Romanian
    • Russian
    • Tajik
    • Tatar
    • Turkmen
    • Ukrainian
    • Uzbek
  • It is capable of encrypting local and network drives.
  • It deletes shadow copies.
  • Due to the nature of how it drops its ransom notes, it is capable of printing physical copies of its ransom note through printers it has found in the network.

Ransomware Routine

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

  • dtb.dat
  • autorun.inf
  • boot.ini
  • desktop.ini
  • ntuser.dat
  • iconcache.db
  • bootsect.bak
  • ntuser.dat.log
  • thumbs.db
  • Bootfont.bin
  • RECOVER-FILES.txt

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

  • \Windows
  • \Program Files
  • \Tor Browser
  • \ProgramData\
  • \cache2\entries\
  • \Low\Content.IE5\
  • \User Data\Default\Cache\
  • \All Users

It renames encrypted files using the following names:

  • {Original Filename}.{Original File Extension}.{Random Characters}

It drops the following file(s) as ransom note:

  • {Encrypted Directory}\RECOVER-FILES.txt

It avoids encrypting files with the following file extensions:

  • .lnk
  • .exe
  • .sys
  • .dll

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

16.274.04

FIRST VSAPI PATTERN DATE:

08 Oct 2020

VSAPI OPR PATTERN File:

16.275.00

VSAPI OPR PATTERN Date:

09 Oct 2020

Step 1

Trend Micro Predictive Machine Learning detects and blocks malware at the first sign of its existence, before it executes on your system. When enabled, your Trend Micro product detects this malware under the following machine learning name:

     
    • Troj.Win32.TRX.XXPE50FFF037

Step 2

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 3

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 4

Restart in Safe Mode

[ Learn More ]

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.
  • %Program Data%\dtb.dat
  • {Encrypted Directory}\RECOVER-FILES.txt

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win32.EGREGOR.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 encrypted files from backup.


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