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You have been re-routed to the Trojan:Win32/Loktrom.B write up because Trojan%3aWin32%2fLoktrom.B has been renamed to Trojan:Win32/Loktrom.B
 

Trojan:Win32/Loktrom.B


Microsoft security software detects and removes this threat.

If this threat asks you to pay a fee or fine, do not pay it. The message is a fraud.

This family of ransomware locks your PC and displays a full-screen message (commonly called a "lock screen").

It pretends to be from 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 onto your PC from a drive-by download attack. It might also have installed itself on your PC if you visit a compromised webpage.

You can read more on our ransomware page.



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

The following free Microsoft software detects and removes this threat:

However, because this threat can lock your screen, you might not be able to download or run antivirus or antimalware software. If that happens, you will need to use the free tool Windows Defender Offline:

The following articles may help if you're having trouble getting the tool to work:

After you've used Windows Defender Offline, you should update your security software and run a full scan:

Even if we've already detected and removed this particular threat, running a full scan might find other malware that is hiding on your PC.

You can also visit the Microsoft virus and malware community for more help.

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

Trojan:Win32/Loktrom.B 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

Trojan:Win32/Loktrom.B 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: 1.171.46.0 and higher
First detected on: Nov 12, 2012
This entry was first published on: Nov 12, 2012
This entry was updated on: Mar 14, 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)