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WORM_AINSLOT.SMK

September 16, 2016
 ALIASES:

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

 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

Initial Samples Received Date:

20 Aug 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

NOTES:

Trend customers:

    Keep your pattern and scan engine files updated. Trend Micro antivirus software can clean or remove most types of computer threats. Malware, though, such as Trojans, scripts, overwriting viruses and joke programs which are identified as uncleanable, should simply be deleted.

All Internet users:

  • Use HouseCall - the Trend Micro online threat scanner to check for malware that may already be on your PC.
  • Catch malware/grayware before they affect your PC or network. Secure your Web world with Trend Micro products that offer the best anti-threat and content security solutions for home users, corporate users, and ISPs. Go here for more information on Trend Micro products that fit your needs.


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