Threat Encyclopedia

TROJ_DROPPER.TKD

Publish date: September 05, 2011

ANALYSIS BY

Sabrina Lei Sioting


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 is related to a possible targeted attack.

To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.

It uses legitimate program files in its attachments in order to hide its malicious routines.

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

It executes the files it drops, prompting the affected system to exhibit the malicious routines they contain.

TECHNICAL DETAILS

File Size:

61,440 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

02 Sep 2011

Payload:

Drops files

Arrival Details

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

Installation

This Trojan drops the following files:

  • %User Profile%Application Data\Locations\winhlps.exe - detected as BKDR_SMALL.NAE

(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.)

It drops the following non-malicious file:

  • %User Temp%\{random}.doc

(Note: %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 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.)

Dropping Routine

This Trojan executes the files it drops, prompting the affected system to exhibit the malicious routines they contain.

NOTES:
It drops a non-malicious Microsoft Word document in order to mask the malicious routines it performs.

SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

8.396.08

FIRST VSAPI PATTERN DATE:

02 Sep 2011

VSAPI OPR PATTERN File:

8.397.00

VSAPI OPR PATTERN Date:

03 Sep 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

Remove malware files dropped/downloaded by TROJ_DROPPER.TKD

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.
  • %User Profile%Application Data\Locations

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_DROPPER.TKD. 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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