Analysis by: Kathleen Notario
ALIASES:

n/a

 PLATFORM:

Windows 2000, XP, Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

This Trojan checks the drives from A to Z. If the said drive is removable, it will list all the files on the said drive on certain files.

It does not have backdoor capabilities.

It does not have network propagation capabilities.

It does not have rootkit capabilities.

It does not update itself.

It does not have information theft capabilities.

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.

  TECHNICAL DETAILS

File Size: Varies
File Type: PE
Memory Resident: Yes
Initial Samples Received Date: 10 Nov 2010
Payload: Drops 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.

Installation

This Trojan creates the following folders:

  • %Current%\{A070B132-UBB6-40A9-A24D-D5B909B5F864}

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
DEFAULT = {malware path and filename}

It modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = Explorer.exe, {malware path and filename}

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

Other System Modifications

This Trojan adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
CabinetState
FullPath = 1

Dropping Routine

This Trojan drops the following files:

  • %Current%\{A070B132-UBB6-40A9-A24D-D5B909B5F864}\20101112_u\~dbthdu.db - non-malicious file
  • %Current%\{A070B132-UBB6-40A9-A24D-D5B909B5F864}\20101112_a\~dbthda.db - non-malicious file

NOTES:

Other Details

Based on analysis of the codes, it has the following capabilities:

It may arrive on a system as the following files:

  • startup.exe - creates the autostart registry entries
  • svchost.exe - performs the main routine

This Trojan checks the drives from A to Z. If the said drive is removable, it will list all the files on the said drive on the following files:

  • %Current%\{A070B132-UBB6-40A9-A24D-D5B909B5F864}\20101112_u\~dbthdu.db
  • %Current%\{A070B132-UBB6-40A9-A24D-D5B909B5F864}\20101112_a\~dbthda.db

The contents of ~dbthda.db is the list files if the drive is A, if any other letter the list of files will be written on ~dbthdu.db.

  SOLUTION

Minimum Scan Engine: 8.900
VSAPI PATTERN File: 7.610.02
VSAPI PATTERN Date: 10 Nov 2010
VSAPI PATTERN Date: 11/10/2010 12:00:00 AM

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

Identify and terminate files detected as TROJ_SMALL.LIC

[ Learn More ]
  1. 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.
  2. 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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • DEFAULT = {malware path and filename}
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\CabinetState
    • FullPath = 1

Step 4

Restore this modified 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 NT\CurrentVersion\Winlogon
    • From: Shell = Explorer.exe, {malware path and filename}
      To: Explorer.exe

Step 5

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.
 %Current%\{A070B132-UBB6-40A9-A24D-D5B909B5F864}

Step 6

Scan your computer with your Trend Micro product to delete files detected as TROJ_SMALL.LIC. 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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