ALIASES:

Worm:Win32/Folstart.A (Microsoft); W32/Rotinom (McAfee); Trojan Horse (Symantec); Trojan.Win32.Agent2.ldt (Kaspersky); Trojan.Win32.Rotinom.b (v) (Sunbelt); Worm.Generic.311224 (FSecure)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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

  TECHNICAL DETAILS

File Size: 178,440 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 04 Nov 2011

Arrival Details

This worm 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 copies of itself into the affected system:

  • %Application Data%\Start\update.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.)

It creates the following folders:

  • %Application Data%\S-1-5-31-1286970278978-5713669491-166975984-320
  • %Application Data%\S-1-5-31-1286970278978-5713669491-166975984-320\dmc
  • %Application Data%\S-1-5-31-1286970278978-5713669491-166975984-320\tlsr
  • %Application Data%\S-1-5-31-1286970278978-5713669491-166975984-320\Rotinom
  • %Application Data%\Start
  • %System Root%\1747c0ad1ded0fd7f4f3cfbbc18ab5c3ab1e5ed6_0c78fc7ee2416d642ed66279e236\

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.. %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

Other System Modifications

This worm modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = 2

(Note: The default value data of the said registry entry is 2.)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
HideFileExt = 1

(Note: The default value data of the said registry entry is 1.)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Shell Folders
Startup = "%Application Data%\Start"

(Note: The default value data of the said registry entry is %User Startup%.)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
User Shell Folders
Startup = "%Application Data%\Start"

(Note: The default value data of the said registry entry is %USERPROFILE%\Start Menu\Programs\Startup.)

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.200

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

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: Hidden=2
      To: Hidden=2
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: HideFileExt=1
      To: HideFileExt=1
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders
    • From: Startup="%Application Data%\Start"
      To: Startup=%User Startup%
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders
    • From: Startup="%Application Data%\Start"
      To: Startup=%USERPROFILE%\Start Menu\Programs\Startup

Step 3

Search and delete these folders

[ 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.
  • %Application Data%\S-1-5-31-1286970278978-5713669491-166975984-320
  • %Application Data%\S-1-5-31-1286970278978-5713669491-166975984-320\dmc
  • %Application Data%\S-1-5-31-1286970278978-5713669491-166975984-320\tlsr
  • %Application Data%\S-1-5-31-1286970278978-5713669491-166975984-320\Rotinom
  • %Application Data%\Start
  • %System Root%\1747c0ad1ded0fd7f4f3cfbbc18ab5c3ab1e5ed6_0c78fc7ee2416d642ed66279e236\

Step 4

Scan your computer with your Trend Micro product to delete files detected as WORM_AUTORUN.SMI. 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.


Did this description help? Tell us how we did.