Analysis by: Rhena Inocencio

 ALIASES:

JS/TrojanDropper.Agent.NCS (ESET), Trojan:JS/CryptoRa.A (F-Secure), JS/Ransom.RAA!tr (Fortinet)

 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: Via email

This ransomware is written in Jscript, a scripting language designed for Windows. Particularly, it is for Internet Explorer. Note that it requires Windows Script Host execution.

To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

This is the Trend Micro detection for files that exhibit certain behaviors.

  TECHNICAL DETAILS

File Size: 572,952 bytes
File Type: JS
Memory Resident: Yes
Initial Samples Received Date: 14 Jun 2016
Payload: Encrypts files, Displays message/message boxes

Arrival Details

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
(default) = "{malware path and filename}.js argument"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\RAA\Raa-fnl

It deletes the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\VSS

(Note: This is the Windows Volume Shadow Copy (VSS) Service)

Other Details

This Trojan encrypts files with the following extensions:

  • doc
  • xls
  • rft
  • pdf
  • dbf
  • jpg
  • dwg
  • cdr
  • psd
  • cd
  • mdb
  • png
  • lcd
  • zip
  • rar
  • csv

It drops the following file(s)/component(s):

  • %Desktop%\!!!README!!!{unique ID}.rtf - ransom note
  • %My Documents%\doc_attached_{5 random characters} - word document
  • %My Documents%\st.exe – detected as TSPY_FAREIT.RAA

    (Note: %My Documents% is usually C:\Documents and Settings\{user name}\My Documents on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\Documents on Windows Vista and 7.)

This is the Trend Micro detection for:

  • RAA ransomware

It does the following:

  • It encrypts files in all available drives and appends the extension .locked
  • It avoids encrypting files in folders/directories containing the following strings:
    • WINDOWS
    • RECYCLER
    • Program Files
    • Program Files (x86)
    • Windows
    • Recycle.Bin
    • RECYCLE.BIN
    • Recycler
    • TEMP
    • APPDATA
    • AppData
    • Temp
    • ProgramData
    • Microsoft

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 12.590.07
FIRST VSAPI PATTERN DATE: 14 Jun 2016
VSAPI OPR PATTERN File: 12.591.00
VSAPI OPR PATTERN Date: 15 Jun 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

Remove the malware/grayware file dropped/downloaded by RANSOM_JSRAA.A. (Note: Please skip this step if the threat(s) listed below have already been removed.)

Step 4

Scan your computer with your Trend Micro product and note files detected as RANSOM_JSRAA.A

Step 5

Restart in Safe Mode

[ Learn More ]

Step 6

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
    • (default) = "{malware path and filename}.js argument"

Step 7

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.

  • In HKEY_CURRENT_USER
    • RAA

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_JSRAA.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 9

Restore encrypted files from backup.


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