TROJ_REFROSO.AD

October 09, 2012
 Analysis by: Rhena Inocencio
 ALIASES:

VirTool:Win32/Injector.gen!AD (Microsoft)

 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

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It bears the file icons of certain applications to avoid easy detection and consequent removal.

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

  TECHNICAL DETAILS

File Size:

142,848 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

12 Oct 2010

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This Trojan bears the file icons of the following applications:

  • MSI Installer Package Icon

It injects itself into the following processes as part of its memory residency routine:

  • explorer.exe

It terminates itself if it finds the following processes in the affected system's memory:

  • The Wireshark Network Analyzer
  • Process Monitor - Sysinternals: www.sysinternals.com
  • File Monitor - Sysinternals: www.sysinternals.com
  • Registry Monitor - Sysinternals: www.sysinternals.com

Download Routine

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

NOTES:
It connects to a remote site to dowload a file. However, the URL where the malware connects to is not in the malware body.

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

7.532.10

FIRST VSAPI PATTERN DATE:

12 Oct 2010

VSAPI OPR PATTERN File:

7.533.00

VSAPI OPR PATTERN Date:

13 Oct 2010

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

Restart in Safe Mode

[ Learn More ]

Step 3

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • (Default) = "{Malware Path and File Name}"

Step 4

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