TROJ_MDROP.EVL

August 16, 2012
 Analysis by: Jasen Sumalapao
 ALIASES:

Exploit:SWF/ShellCode.G (Microsoft), ARC:Embedded (Kaspersky), Trojan.Mdropper (Symantec), MSWord/SWFDropper.A!Camelot (Authentium)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Via email, Downloaded from the Internet

This Trojan exploits CVE-2012-1535, an Adobe vulnerability that is already patched before the release of this Trojan.

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

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users. It may be downloaded by other malware/grayware/spyware from remote sites. It may be manually installed by a user.

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

  TECHNICAL DETAILS

File Size:

298,496 bytes

File Type:

DOC

Initial Samples Received Date:

15 Aug 2012

Payload:

Drops files

Arrival Details

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

It may be downloaded by other malware/grayware/spyware from remote sites.

It may be manually installed by a user.

Installation

This Trojan drops and executes the following files:

  • %User Profile%\Local Settings\~WORDL.tmp - detected as BKDR_BRIBA.EVL
  • %User Profile%\Application Data\taskman.dll - detected as BKDR_BRIBA.EVL

(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 takes advantage of the following software vulnerabilities to drop malicious files:

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

NOTES:

This is the Trend Micro detection for a Microsoft Office Word document with an embedded malicious Flash file.

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

9.326.07

FIRST VSAPI PATTERN DATE:

15 Aug 2012

VSAPI OPR PATTERN File:

9.327.00

VSAPI OPR PATTERN Date:

16 Aug 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/grayware files dropped/downloaded by TROJ_MDROP.EVL

Step 3

Scan your computer with your Trend Micro product to delete files detected as TROJ_MDROP.EVL. 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 4

Download and apply this security patch Refrain from using these products until the appropriate patches have been installed. Trend Micro advises users to download critical patches upon release by vendors.


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