ALIASES:

Win32/TrojanDownloader.Agent.AWN (ESET)

 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

Infection Channel: Dropped by other malware

This Trojan may be dropped by other malware.

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

However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size: 17,408 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 04 Nov 2014
Payload: Downloads files

Arrival Details

This Trojan may be dropped by the following malware:

  • TROJ_MDROP.EXT

Installation

This Trojan drops the following copies of itself into the affected system and executes them:

  • %Program Files%\Windows NT\Accessories\PrivacIE\mtset.exe (If user is Administrator)
  • "%User Profile%\Applications\PrivacIE\mtset.exe (If user is not Administrator)

(Note: %Program Files% is the Program Files folder, where it usually is C:\Program Files on all Windows operating system versions; C:\Program Files (x86) for 32-bit applications running on Windows 64-bit operating systems.. %User Profile% is a user's profile folder, where it usually is C:\Documents and Settings\{user name} on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name} 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.)

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\Software\Microsoft\
CurrentVersion\Run
PHIME2012ASync = "%Program Files%\Windows NT\Accessories\PrivacIE\mtset.exe" (If user is Administrator)

HKEY_LOCAL_MACHINE\Software\Microsoft\
CurrentVersion\Run
PHIME2012ASync = "%User Profile%\Applications\PrivacIE\mtset.exe" (If user is not Administrator)

Download Routine

This Trojan accesses the following websites to download files:

  • http://www.{BLOCKED}c.or.jp/css/js/csj.php?page_id=55

It saves the files it downloads using the following names:

  • %User Temp%\msupdata.exe

(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.

Other Details

However, as of this writing, the said sites are inaccessible.

  SOLUTION

Minimum Scan Engine: 9.700

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

Remove the malware/grayware file that dropped/downloaded TROJ_DLOADER.EXT. (Note: Please skip this step if the threat(s) listed below have already been removed.)

     
    • TROJ_MDROP.EXT

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

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_LOCAL_MACHINE\Software\Microsoft\CurrentVersion\Run
    • PHIME2012ASync = "%Program Files%\Windows NT\Accessories\PrivacIE\mtset.exe" (If user is Administrator)
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\CurrentVersion\Run
    • PHIME2012ASync = "%User Profile%\Applications\PrivacIE\mtset.exe" (If user is not Administrator)

Step 5

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