RANSOM_AESBAT.A

February 09, 2018
 Analysis by: Christian Noel Olalia
 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:

Dropped by other malware

This Ransomware may arrive bundled with malware packages as a malware component.

It deletes itself after execution.

It encrypts files with specific file extensions. It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

41,434 bytes

File Type:

BAT

Memory Resident:

No

Initial Samples Received Date:

11 Oct 2017

Payload:

Displays message/message boxes, Encrypts files

Arrival Details

This Ransomware may arrive bundled with malware packages as a malware component.

Process Termination

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

  • postgres.exe
  • sqlwriter.exe
  • sqlbrowser.exe
  • sqlagent.exe
  • sqlservr.exe

Other Details

This Ransomware requires the following additional components to properly run:

  • aescrypt.exe
  • eraser1.exe
  • eraser.dll

It does the following:

  • Execute the following commands:
    • vssadmin.exe Delete Shadows /All /Quiet
    • bcdedit /set recoveryenabled No
    • bcdedit /set bootstatuspolicy ignoreallfailures
  • DECRYPT_INSTRUCTIONS.html displays the following:

It deletes itself after execution.

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .docx
  • .doc
  • .pdf
  • .xlsx
  • .xls
  • .csv
  • .txt
  • .dcm
  • .dicom
  • .zip
  • .rar
  • .tgz
  • .jpg
  • .jpeg
  • .avi
  • .mp4
  • .mpeg
  • .ppt
  • .pptx
  • .cfg
  • .db
  • .accdb
  • .mdb
  • .fdb
  • .xml
  • .myd
  • .dbf
  • .sql
  • .mdf
  • .accdt
  • .accdc
  • .crt
  • .p7b
  • .cer
  • .crt
  • .pfx
  • .p12
  • .pem
  • .bak
  • .bkf
  • .tsbak
  • .sav
  • .cat
  • .abd
  • .abf
  • .cfx
  • .prproj

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

  • {Encrypted file path}\DECRYPT_INSTRUCTIONS.html

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.712.08

FIRST VSAPI PATTERN DATE:

11 Oct 2017

VSAPI OPR PATTERN File:

13.713.00

VSAPI OPR PATTERN Date:

12 Oct 2017

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_AESBAT.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 these files

[ 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.
  • {Malware Path}\aescrypt.exe
  • {Malware Path}\eraser1.exe
  • {Malware Path}\eraser.dll
  • {Encrypted file path}\DECRYPT_INSTRUCTIONS.html

Step 5

Scan your computer with your Trend Micro product to delete files detected as RANSOM_AESBAT.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 the following Trend Micro Support pages for more information:

Step 6

Restore encrypted files from backup.


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