RANSOM_RASOON.A

 Analysis by: Marcus Ma. Antonio Capistrano

 ALIASES:

Trojan-Ransom.MSIL.Agent.gpq (KASPERSKY), Ransom:MSIL/Rasoon.A (MICROSOFTRansom:MSIL/Rasoon.A), RDN/Ransom (NAI)

 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, 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 is capable of encrypting files in the affected system.

It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

29,184 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

01 Jan 2018

Payload:

Steals information, Connects to URLs/IPs, Encrypts files, Drops files, Displays message/message boxes

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 Temp%\ErrorLogAes.bin

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on 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.)

Information Theft

This Ransomware gathers the following data:

  • Public IP address
  • Computer Name
  • Encryption routine duration
  • Number and size of files encrypted

Stolen Information

This Ransomware sends the data it gathers to the following email addresses via SMTP:

  • pulpy2@{BLOCKED}k.li

Other Details

This Ransomware does the following:

  • After its encryption routine it opens the dropped ransom note file using the following commands:
    %System%\NOTEPAD.EXE %Desktop%\Instruction.txt
  • If the running ransomware is located at %System Root%, it deletes itself after its execution

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

It is capable of encrypting files in the affected system.

Ransomware Routine

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

  • .aes
  • .sys
  • .SYS
  • bootmgr
  • BOOTNXT
  • .ani
  • .cpl
  • .cur
  • .dat
  • .deskthemepack
  • .diagcab
  • .diagpkg
  • .dmp
  • .drv
  • .hlp
  • .icl
  • .msp
  • .msstyles
  • .ocx
  • .rtp
  • .themepack
  • .CAB
  • .settingcontent-ms
  • .lnk
  • Instruction.txt
  • {malware file}

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

  • C:\Drivers
  • Program Files
  • Windows
  • ProgramData
  • C:\Users\All Users\Microsoft
  • C:\Users\Default\AppData\Roaming\Microsoft
  • AppData\Local\Packages
  • AppData
  • WINDOWS
  • Desctop

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

  • .aes

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

  • {all directories*}\Instruction.txt

It leaves text files that serve as ransom notes containing the following text:

  • Hi, all your files have been encrypted. You can decipher if you write to me on the mail: pulpy2@{BLOCKED}k.li Otherwise, all your files will be deleted within 2 days without any problems!

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.880.02

FIRST VSAPI PATTERN DATE:

02 Jan 2018

VSAPI OPR PATTERN File:

13.881.00

VSAPI OPR PATTERN Date:

03 Jan 2018

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

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.  
  • {all directories*}\Instruction.txt
  • %User Temp%\ErrorLogAes.bin

Step 4

Scan your computer with your Trend Micro product to delete files detected as RANSOM_RASOON.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 5

Restore encrypted files from backup.


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