Threat Encyclopedia

TROJ_MDROP.ZD

Publish date: October 09, 2012

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: Yes

  • In the wild: Yes

OVERVIEW

Infection Channel:

Spammed via email


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:

207,338 bytes

File Type:

Other

Memory Resident:

No

Initial Samples Received Date:

26 Apr 2012

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 non-malicious file:

  • %User Temp%\AAAA

(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.)

Dropping Routine

This Trojan drops the following files:

  • %Windows%\Temp\s{random}.dat - detected as BKDR_VISEL.FO

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

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

NOTES:

Upon execution, this Trojan opens its dropped non-malicious .HWP file %User Temp%\AAAA in order to hide its malicious routines from the user.

SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

8.942.04

FIRST VSAPI PATTERN DATE:

26 Apr 2012

VSAPI OPR PATTERN File:

8.943.00

VSAPI OPR PATTERN Date:

26 Apr 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

Remove malware files dropped/downloaded by TROJ_MDROP.ZD

Step 3

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.
%User Temp%\AAAA

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_MDROP.ZD. 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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