W2KM_DRIDEX.YSO

October 26, 2015
 Analysis by: Mar Philip Elaurza
 ALIASES:

W97M.Downloader (Symantec), TrojanDownloader:W97M/Adnel (Microsoft), W97M/Downloader.apn (McAfee), Trojan-Downloader.MSWord.Agent.uc (Kaspersky), VBA/TrojanDownloader.Agent.AFO (ESET-NOD32)

 PLATFORM:

Windows

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

  • 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 executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size:

71,680 bytes

File Type:

DOC

Memory Resident:

Yes

Initial Samples Received Date:

26 Oct 2015

Arrival Details

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

Download Routine

This Trojan connects to the following website(s) to download and execute a malicious file:

  • http://www.{BLOCKED}ade.com/34563234g/32tg32vc.exe

It saves the files it downloads using the following names:

  • %User Temp%\etsbabk.exe - detected as TSPY_DRIDEX.YYSOP

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

  SOLUTION

Minimum Scan Engine:

9.8

FIRST VSAPI PATTERN FILE:

12.104.04

FIRST VSAPI PATTERN DATE:

23 Oct 2015

VSAPI OPR PATTERN File:

12.105.00

VSAPI OPR PATTERN Date:

24 Oct 2015

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Remove malware/grayware files dropped/downloaded by W2KM_DRIDEX.YSO. (Note: Please skip this step if the threats listed below have already been removed.)

     
    • TSPY_DRIDEX.YYSOP

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as W2KM_DRIDEX.YSO. 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.

Step 6

Enable the macro virus protection in Microsoft Office Applications

[ Learn More ]


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