Analysis by: Karl Dominguez
 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

This Trojan may be downloaded by other malware/grayware/spyware from remote sites. It may be unknowingly downloaded by a user while visiting malicious websites.

As of this writing, the said sites are inaccessible.

It terminates itself if it detects it is being run in a virtual environment.

  TECHNICAL DETAILS

File Size: Varies
File Type: PE
Memory Resident: Yes
Initial Samples Received Date: 26 Feb 2011
Payload: Terminates itself if it detects it is being run in a virtual environment., Downloads files

Arrival Details

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

It may be unknowingly downloaded by a user while visiting malicious websites.

Installation

This Trojan 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

Autostart Technique

This Trojan drops the following file(s) in the Windows User Startup folder to enable its automatic execution at every system startup:

  • {random characters}.exe

Download Routine

This Trojan accesses the following websites to download files:

  • {BLOCKED}ok.com
  • {BLOCKED}eh.com
  • {BLOCKED}hs.com
  • {BLOCKED}de.com
  • {BLOCKED}ij.com
  • {BLOCKED}uh.com

As of this writing, the said sites are inaccessible.

Other Details

This Trojan terminates itself if it detects it is being run in a virtual environment.

  SOLUTION

Minimum Scan Engine: 8.900
VSAPI PATTERN File: 7.859.00
VSAPI PATTERN Date: 26 Feb 2011
VSAPI PATTERN Date: 2/26/2011 12:00:00 AM

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

Scan your computer with your Trend Micro product and note files detected as TROJ_REFROSO.SMG

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Search and delete the file detected as TROJ_REFROSO.SMG

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files in the search result.

Step 5

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