TROJ_DROPR.NS

October 09, 2012
 Analysis by: Abraham Latimer Camba
 PLATFORM:

Windows 2000, Windows XP, Windows 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 arrives as an attachment to email messages spammed by other malware/grayware or malicious users. 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 executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

140,288 bytes

File Type:

EXE, Other

Memory Resident:

No

Initial Samples Received Date:

18 Sep 2012

Arrival Details

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

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 Trojan creates the following folders:

  • %User Profile%\Application Data\Locations

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

Autostart Technique

This Trojan creates the following registry entries to enable automatic execution of dropped component at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
CurrentVersion\Run
WindowsUpdate = "%User Profile%\Application Data\Locations\WindowsUpdate.exe"

Dropping Routine

This Trojan drops the following files:

  • %User Profile%\Application Data\Locations\WindowsUpdate.exe
  • %User Temp%\~DF4E74.doc

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.)

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

Other Details

This Trojan deletes itself after execution.

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

9.406.03

FIRST VSAPI PATTERN DATE:

19 Sep 2012

VSAPI OPR PATTERN File:

9.407.00

VSAPI OPR PATTERN Date:

19 Sep 2012

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

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\CurrentVersion\Run
    • WindowsUpdate = "%User Profile%\Application Data\Locations\WindowsUpdate.exe"

Step 3

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.  
  • %User Profile%\Application Data\Locations

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_DROPR.NS. 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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