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Worm:Win32/Mothyfil.B

First posted on 09 November 2015.
Source: Microsoft

Aliases :

There are no other names known for Worm:Win32/Mothyfil.B.

Explanation :

Threat behavior

Installation
This threat can create files on your PC, including:

• %SystemRoot%\2b6c0.exe
• %SystemRoot%\b6e69.exe
• %SystemRoot%\x1ac5.exe

It modifies the registry so that it runs each time you start your PC. For example:

In subkey: HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
Sets value: "Shell"
With data: "explorer.exe , b6e69.exe"
In subkey: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
Sets value: "63648"
With data: "x1ac5.exe"

This threat tries to bypass your firewall by modifying the registry. For example:

HKLM\system\currentcontrolset\services\sharedaccess\parameters\firewallpolicy

The malware uses code injection to make it harder to detect and remove. It can inject code into running processes.



Payload


Bypasses firewall



This threat can modify, bypass, or disable your firewall. It can do this by changing your firewall allowed list, or by adding a new rule so that it, or other applications, aren't detected.

You might need to restore your Windows Firewall settings.



This malware description was published using automated analysis of file SHA1 ad43205f7256d44b9eb8d83bbc40f340e380a609.

Symptoms

The following can indicate that you have this threat on your PC:

• You see a file similar to:
  • %SystemRoot%\2b6c0.exe
  • %SystemRoot%\b6e69.exe
  • %SystemRoot%\x1ac5.exe

• You see registry modifications such as:
  
  • In subkey: HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    Sets value: "Shell"
    With data: "explorer.exe , b6e69.exe"
    
    
  • In subkey: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    Sets value: "63648"
    With data: "x1ac5.exe"
    
    
  • In subkey: HKLM\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    Sets value: "\winlogon.exe"
    With data: "\winlogon.exe:*:enabled:@shell32.dll,-1"
    
    

Last update 09 November 2015

 

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