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You have been re-routed to the Ransom:Win32/Loktrom.B write up because Trojan:Win32/Loktrom.B has been renamed to Ransom:Win32/Loktrom.B
 

Ransom:Win32/Loktrom.B


Microsoft security software detects and removes this threat.

This threat locks your PC and displays a full-screen message, commonly called a "lock screen".

It pretends to be from the FBI or a national police force and tries to scare you into paying a fine to unlock your PC.

See the Technical information tab for examples of the lock screen.

Typically, this threat gets on your PC when you visit a hacked webpage.

You can read more about this type on malware on our ransomware page.

Find out ways that malware can get on your PC.



What to do now

Microsoft doesn’t recommend you pay the fine. There is no guarantee that paying the ransom will give you access to your files.

If you've already paid, see our ransomware page for help on what to do now.

Run antivirus or antimalware software

Use the following free Microsoft software to detect and remove this threat:

You should also run a full scan. A full scan might find other, hidden malware.

Advanced troubleshooting

To restore your PC, you might need to download and run Windows Defender Offline. See our advanced troubleshooting page for more help.

Get more help

You can also visit our advanced troubleshooting page or search the Microsoft virus and malware community for more help.

If you’re using Windows XP, see our Windows XP end of support page.

Threat behavior

Installation

It changes the following registry entry so that it runs each time you start your PC:

In subkey: HKCU\Software\Microsoft\WindowsNT\CurrentVersion\Winlogon
Sets value: "Shell"
With data: "<malware file name>"

In subkey: HKLM\Software\Microsoft\Windows\CurrentVersion\Run
Sets value: "<random name>", for example "explorer"
With data: "<malware file name>"

Payload

Prevents you from accessing your desktop

This threat displays a full-screen message that covers all other windows, rendering your PC unusable (this full-screen message is also known as a "lock screen"). It is a fake warning pretending to be from a legitimate institution which claims an association with Windows and Microsoft Security Essentials. This is untrue and is another method the trojan's authors are employing to make the threat seem legitimate.

The message states that illegal activity has been detected on your PC and that you must send a payment to a mobile phone account to regain access.

You shouldn't pay the "fine" because there is no guarantee that it will unlock your PC.

The screen might look like:

Stops processes

This threat stops the explorer.exe process by running the following command:

taskkill /F /IM explorer.exe

Analysis by Wei Li and Alden Pornasdoro


Symptoms

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

  • You might be unable to access your PC, and instead see the following message:

     

Prevention


Alert level: Severe
First detected by definition: 1.139.1882.0
Latest detected by definition: 1.191.347.0 and higher
First detected on: Nov 12, 2012
This entry was first published on: Nov 12, 2012
This entry was updated on: Aug 25, 2014

This threat is also detected as:
  • Spyware/Win32.Zbot (AhnLab)
  • TR/Ransom.EZ.577 (Avira)
  • Trojan.Ransomlock!g33 (Symantec)
  • Trojan.Winlock.6049 (Dr.Web)
  • Trojan-Dropper.Win32.Dapato (Ikarus)
  • Trojan-Ransom.Win32.Gimemo.attq (Kaspersky)