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Virus Profile: Medfos.b

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Virus Profile information details
Risk Assessment: Home Low | Corporate Low
Date Discovered: 4/28/2012
Date Added: 4/28/2012
Origin: N/A
Length: Varies
Type: Trojan
Subtype: Win32
DAT Required: 6695
Removal Instructions
   
 
 
   

Description

This is a Trojan detection. Unlike viruses, Trojans do not self-replicate. They are spread manually, often under the premise that they are beneficial or wanted. The most common installation methods involve system or security exploitation, and unsuspecting users manually executing unknown programs. Distribution channels include email, malicious or hacked web pages, Internet Relay Chat (IRC), peer-to-peer networks, etc.

Aliases

  • Kaspersky -  HEUR:Trojan.Win32.Generic
  • Microsoft -  Trojan:Win32/Medfos.A
  • Nod32     -  Win32/Medfos.S
  • Antivir      -  TR/Midhos.A 

Indication of Infection

Network activity with servers mentioned above.

Methods of Infection

Trojans do not self-replicate. They are spread manually, often under the premise that the executable is something beneficial. Distribution channels include IRC, peer-to-peer networks, newsgroup postings, email spam, etc.
   

Virus Characteristics

----------Updated on June 1st, 2012---------------------------------

Aliases

  • Kaspersky  - HEUR:Trojan.Win32.Generic
  • BitDefender- Gen:Variant.Zusy.7412
  • Ikarus     - Trojan.Win32.Medfos
  • Microsoft  - Trojan:Win32/Medfos.A

Upon execution, the Trojan connects to the site "11ikaod.cd[Removed]lp.com" through remote port 80 to download other malicious files.

The following registry value has been added.

  • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run\astfac = "rundll32.exe"C:\DOCUME~1\User\LOCALS~1\Temp\astfac.dll

Above mentioned registry ensures that, the Trojan registers itself with the compromised system and execute itself upon every boot.

The following file has been added to the system.

  • %Temp%\astfac.dll

After execution, the Trojan deletes itself from the compromised system.

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Medfos.b is detection for this Trojan that downloads other malicious files from malicious sites.

Upon execution the Trojan tries to connect the following sites:

  • d3lvr7[Removed]nt.net
  • 2.17.[Removed].239
  • 184.50.[Removed].239

When executed it may copies itself into the following location in random names:

  • %Temp%/[Random_name].dll

Communicates with a remote host

Medfos.b connects to various remote servers using HTTP protocol (port 80) and attempts to download the arbitrary files. The Trojan was observed to contact domains with the following suffixes:

  • [Removed].com
  • [Removed.com
  • [Removed].net
   

All Users:

Please use the following instructions for all supported versions of Windows to remove threats and other potential risks:

1.Disable System Restore .

2.Update to current engine and DAT files for detection and removal.

3.Run a complete system scan.

Modifications made to the system Registry and/or INI files for the purposes of hooking system startup, will be successfully removed if cleaning with the recommended engine and DAT combination (or higher).

1. Please go to the Microsoft Recovery Console and restore a clean MBR.

On windows XP:

Insert the Windows XP CD into the CD-ROM drive and restart the computer.
When the "Welcome to Setup" screen appears, press R to start the Recovery Console.
Select the Windows installation that is compromised and provide the administrator password
Issue 'fixmbr' command to restore the Master Boot Record
Follow onscreen instructions
Reset and remove the CD from CD-ROM drive.


On Windows Vista and 7:

Insert the Windows CD into the CD-ROM drive and restart the computer.
Click on "Repair Your Computer"
When the System Recovery Options dialog comes up, choose the Command Prompt.
Issue 'bootrec /fixmbr' command to restore the Master Boot Record
Follow onscreen instructions
Reset and remove the CD from CD-ROM drive.