WORM_DROPPER.TPD

 Analysis by: Cris Nowell Pantanilla

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This worm arrives via removable drives.

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

It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size:

580,833 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

23 Dec 2011

Arrival Details

This worm arrives via removable drives.

Installation

This worm drops the following files:

  • %Windows%\encoder.txt
  • %Windows%\lock.rar
  • %Windows%\mouse.exe
  • %Windows%\run.vbs
  • %Windows%\unlock.exe
  • %Windows%\wscntfy32.exe

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

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

  • %Windows%\my_facebook_photo.exe

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

Autostart Technique

This worm modifies the following entry(ies) to allow itself to run on safe mode:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = "%System%\userinit.exe,%Windows%\wscntfy32.exe,%Windows%\help\svchost.exe"

(Note: The default value data of the said registry entry is %System%\userinit.exe,.)

Propagation

This worm 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=facebook_photo.exe
shellexecute=facebook_photo.exe
shell\Auto\command=facebook_photo.exe

Dropping Routine

This worm executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

Other Details

This worm connects to the following possibly malicious URL:

  • http://{BLOCKED}s.3322.org/encoder.txt?67678

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

8.662.08

FIRST VSAPI PATTERN DATE:

24 Dec 2011

VSAPI OPR PATTERN File:

8.663.00

VSAPI OPR PATTERN Date:

24 Dec 2011

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Scan your computer with your Trend Micro product and note files detected as WORM_DROPPER.TPD

Step 3

Identify and delete files detected as WORM_DROPPER.TPD using either the Startup Disk or Recovery Console

[ Learn More ]

Step 4

Restore this modified registry value

[ 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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Userinit = "%System%\userinit.exe,%Windows%\wscntfy32.exe,%Windows%\help\svchost.exe"
      To: Userinit = "%System%\userinit.exe,"

Step 5

Search and delete these files

[ Learn More ]
There may be some component files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files and folders in the search result.
  • %Windows%\encoder.txt
  • %Windows%\lock.rar
  • %Windows%\mouse.exe
  • %Windows%\run.vbs
  • %Windows%\unlock.exe
  • %Windows%\wscntfy32.exe

Step 6

Search and delete AUTORUN.INF files created by WORM_DROPPER.TPD that contain these strings

[ Learn More ]


[AutoRun]
open=facebook_photo.exe
shellexecute=facebook_photo.exe
shell\Auto\command=facebook_photo.exe

Step 7

Scan your computer with your Trend Micro product to delete files detected as WORM_DROPPER.TPD. 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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