WORM_AINSLOT.VTR


 ALIASES:

Worm:Win32/Ainslot.K (Microsoft); Worm.Win32.AutoRun.avuf (Kaspersky); W32/AutoRun.AVUF!worm (Fortinet)

 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This worm arrives via removable drives. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

  TECHNICAL DETAILS

File Size:

40,960 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

15 Jun 2016

Arrival Details

This worm arrives via removable drives.

It 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 worm drops the following files:

  • {removable drive letter}:\RECYCLER\desktop.ini

It drops the following copies of itself into the affected system:

  • %Windows%\igfxsrvc.exe

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

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
lgxfsrvc = "%Windows%\igfxsrvc.exe"

Propagation

This worm creates the following folders in all removable drives:

  • {removable drive letter}:\RECYCLER

It drops the following copy(ies) of itself in all removable drives:

  • {removable drive letter}:\RECYCLER\S-1-5-21-3441485041-918478196-174860263-1004\run.exe

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

The said .INF file contains the following strings:

[autorun]
open=.\RECYCLER\S-1-5-21-3441485041-918478196-174860263-1004\run.exe
icon=%SystemRoot%\system32\SHELL32.dll,4
action=.\RECYCLER\S-1-5-21-3441485041-918478196-174860263-1004\run.exe
shell\open=.\RECYCLER\S-1-5-21-3441485041-918478196-174860263-1004\run.exe
shell\open\command=.\RECYCLER\S-1-5-21-3441485041-918478196-174860263-1004\run.exe
shell\open\default=1

Other Details

This worm connects to the following possibly malicious URL:

  • http://{BLOCKED}.{BLOCKED}.229.85/naver.php?naver={filename.file extension}
  • http://{BLOCKED}.{BLOCKED}.229.85/naver.php

  SOLUTION

Minimum Scan Engine:

9.8

FIRST VSAPI PATTERN FILE:

12.592.03

FIRST VSAPI PATTERN DATE:

15 Jun 2016

VSAPI OPR PATTERN File:

12.593.80

VSAPI OPR PATTERN Date:

16 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

Identify and terminate files detected as WORM_AINSLOT.VTR

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 3

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • lgxfsrvc = "%Windows%\igfxsrvc.exe"

Step 4

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • {removable drive letter}:\RECYCLER

Step 5

Search and delete AUTORUN.INF files created by WORM_AINSLOT.VTR that contain these strings

[ Learn More ]

[autorun]
open=.\RECYCLER\S-1-5-21-3441485041-918478196-174860263-1004\run.exe
icon=%SystemRoot%\system32\SHELL32.dll,4
action=.\RECYCLER\S-1-5-21-3441485041-918478196-174860263-1004\run.exe
shell\open=.\RECYCLER\S-1-5-21-3441485041-918478196-174860263-1004\run.exe
shell\open\command=.\RECYCLER\S-1-5-21-3441485041-918478196-174860263-1004\run.exe
shell\open\default=1

 

Step 6

Scan your computer with your Trend Micro product to delete files detected as WORM_AINSLOT.VTR. 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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