Removal of Krusop ransomware infection

Also Known As: Krusop virus
Distribution: Low
Damage level: Severe

Krusop ransomware removal instructions

What is Krusop?

Belonging to Djvu ransomware family, Krusop is a high-risk ransomware infection discovered by Michael Gillespie. The purpose of this ransomware is to stealthily infiltrate computers and encrypt data (thereby making it unusable) so that developers could make ransom demands by offering a paid recovery. While encrypting, Krusop adds ".krusop" appendix to each filename (e.g., it would rename "sample.jpg" to "sample.jpg.krusop" and so forth). Additionally, Krusop drops a ransom note ("_readme.txt") in almost all existing folders.

Almost all infections from Djvu family deliver the exact same ransom-demanding message and Krusop is no exception. The message says that files are encrypted and that a unique decryption key is necessary to restore it. These claims are unfortunately true. Krusop compromises data by using an algorithm that generates unique decryption key individually for each victim. For this reason, decryption requires a key. The problem is that all keys are stored in a server which belongs to Krusop's developers and, thus, they demand for a ransom in exchange for each key. In order to decrypt data each victim has to pay a ransom of $980. However, crooks offer a 50% discount for victims who'll contact them within first 72 hours after the encryption. Additionally, these persons promise to decrypt one file for free as a proof that they're actually capable of doing so. However, even if you can afford paying the price, you should never do so. That's because ransomware developers in general are notorious for ignoring victims after they submit payments. In other words, vast majority of ransomware victims submit payments and get nothing in return. They merely support cyber criminals' businesses. Hence, all encouragements to contact these persons and especially submit payments should be ignored. Now we should mention that Krusop encrypts data by using a so-called "offline key" (which is hard-coded) whenever the system has no Internet connection or the aforementioned server is not responding. For this reason, we highly recommend to try Michael Gillespie's decryption tool. If that doesn't work, the only possible solution is to restore everything from a backup.

Screenshot of a message encouraging users to pay a ransom to decrypt their compromised data:

Krusop decrypt instructions

There are many ransomware-type infections that share similarities with Krusop. BORISHORSE, ERIS RANSOMWARE v2, Syrk - the list goes on and on. Although the developers are different, all of these infections behave virtually the same - encrypt data and make ransom demands. There usually are only two major differences: 1) size of ransom, and; 2) type of encryption algorithm used. In most cases, unfortunately, encryptions are performed using RSA, AES, and other high-end cryptographies that generate unique decryption keys. Therefore, if the virus is fully developed and has no bugs/flaws, then restoring data manually (without developers interference) is virtually impossible. The only possible scenarios are ransomware not being fully developed and/or having certain bugs/flaws. Infections of this type present a strong case for maintaining regular data backups. However, it is important to note that locally stored backups will be compromised together with regular data. For this reason, you should store them in a remote server or either unplugged storage device. In fact, we recommend to have multiple backup copies stored in different locations, because there's always a chance that used server/storage device will be damaged.

How did ransomware infect my computer?

The way developers proliferate Krusop is currently unknown. However, ransomware-type infections are usually distributed using email spam campaigns, unofficial software download sources, trojans, and fake software updaters/cracks. Crooks send hundreds of thousands of spam emails consisting of deceptive messages encouraging recipients to open attached links/files which are malicious. In order to create the impression of legitimacy and increase the chance of tricking recipients crooks typically present attachments as invoices, bills, receipts, or other important documents. Peer-to-Peer (P2P) networks, free file hosting and freeware download websites, and other similar third party download sources are used to present malware as legitimate software. Users merely get tricked into downloading and installing malware manually. Trojans are malicious lightweight applications that stealthily infiltrate computers with the intention of injecting additional malware into the system. Fake software updaters and cracks are designed to download/install malicious applications rather than serving their actual purpose, which is updating and activating applications. To sum up, the main reasons for computer infections are poor knowledge and reckless behavior.

Threat Summary:
Name Krusop virus
Threat Type Ransomware, Crypto Virus, Files locker
Detection Names BitDefender (Trojan.GenericKD.32246250), ESET-NOD32 (A Variant Of Win32/Kryptik.GVKF), Emsisoft (Trojan.GenericKD.32246250 (B)), Kaspersky (Trojan-Ransom.Win32.Stop.cp), Full List Of Detections (VirusTotal)
Encrypted Files Extension .krusop
Ransom Demanding Message _readme.txt
Ransom Amount $980/$490
Cyber Criminal Contact gorentos@bitmessage.ch, gorentos2@firemail.cc
Symptoms Can't open files stored on your computer, previously functional files now have a different extension, for example my.docx.locked. A ransom demanding message is displayed on your desktop. Cyber criminals are asking to pay a ransom (usually in bitcoins) to unlock your files.
Additional Information This malware is designed to show fake Windows Update window, modify Windows "hosts" file (to prevent users from accessing cyber security websites) and inject AZORult trojan into the system.
Distribution methods Infected email attachments (macros), torrent websites, malicious ads, unofficial activation and updating tools.
Damage All files are encrypted and cannot be opened without paying a ransom. Additional password stealing trojans and malware infections can be installed together with a ransomware infection.
Removal

To eliminate Krusop virus our malware researchers recommend scanning your computer with Spyhunter.
▼ Download Spyhunter
Free scanner checks if your computer is infected. To remove malware, you have to purchase the full version of Spyhunter.

How to protect yourself from ransomware infections?

In order to prevent PUAs from infiltrating computers users must be very cautious during the download/update/installation processes, as well as when browsing the Internet in general. It is very important to handle all email attachments with care. If the file/link is irrelevant, then do not open anything. Files/links received from suspicious/unrecognizable email addresses should be ignored as well. Moreover, be sure to download programs only from their official sources and, if possible, use direct download links. Same goes for software updates - perform this task only by using implemented functions or tools provided by the official developer. Third party downloaders/updaters/installers often include rogue app and, thus, such tools shouldn't be used. Now every user should be aware that software piracy is a cyber crime and, if that wasn't enough, the risk of infections is extremely high due to the fact that vast majority of cracking tools are fake. For this reason, activating installed software via third party/illegal tools should never be considered. Lastly, be sure to have a reputable Internet security suite installed and running at all times - such software is more than likely to detect and eliminate most of infections before they harm the system. The key to computer safety is caution. If your computer is already infected with Krusop, we recommend running a scan with Spyhunter for Windows to automatically eliminate this ransomware.

Text presented in Krusop ransomware's text file ("_readme.txt"):

ATTENTION!

Don't worry, you can return all your files!
All your files like photos, databases, documents and other important are encrypted with strongest encryption and unique key.
The only method of recovering files is to purchase decrypt tool and unique key for you.
This software will decrypt all your encrypted files.
What guarantees you have?
You can send one of your encrypted file from your PC and we decrypt it for free.
But we can decrypt only 1 file for free. File must not contain valuable information.
You can get and look video overview decrypt tool:
hxxps://we.tl/t-dIIHZji8hl
Price of private key and decrypt software is $980.
Discount 50% available if you contact us first 72 hours, that's price for you is $490.
Please note that you'll never restore your data without payment.
Check your e-mail "Spam" or "Junk" folder if you don't get answer more than 6 hours.


To get this software you need write on our e-mail:
gorentos@bitmessage.ch

Reserve e-mail address to contact us:
gorentos2@firemail.cc

Your personal ID:
-

Screenshot of files encrypted by Krusop (".krusop" extension):

Files encrypted by Krusop

Malware researcher Michael Gillespie has developed a decryption tool that might restore your data if it was encrypted using an "offline key". As we've already mentioned, each victim gets a unique decryption key and all of them are stored in remote servers controlled by cyber criminals. These are categorized as "online keys". However, there are cases when the infected machine has no Internet connection or the server is timing out/not responding. If that is the case, Krusop will use an "offline encryption key", which is hard-coded. Now it is worth mentioning that cyber criminals change offline keys every now and again. This is being done to prevent multiple encryptions with the same key. Meanwhile, Michael Gillespie continually gathers offline keys and updates the decrypter. However, the chances of successful decryption are still very low, since only a very small portion of "offline keys" has been gathered. You can download the decrypter by clicking this link (note that the download link remains the same, despite the fact that decrypter is being continually updated). Your files will be restored only if the list of gathered keys will include the one that was used to encrypt your data.

Screenshot of STOP/Djvu decrypter by Michael Gillespie:

STOP/Djvu ransomware decrypter by Michael Gillespie

As with most of ransomware from Djvu family, Krusop also displays a fake Windows update pop-up during the encryption:

Djvu ransomware family fake update

IMPORTANT NOTE! - Aside from encrypting data, ransomware-type infections from Djvu malware family also installs a trojan-type virus called AZORult, which is designed to steal various account credentials. Moreover, this malware family is designed to add a number of entries to the Windows hosts file. The entries contain URLs of various websites, most of which are related to malware removal. This is carried out with the intention of making users unable to access malware security websites and seek help. Our website (PCrisk.com) is also on the list. Removing these entries, however, is simple - you can find detailed instructions in this article (note that, although the steps are shown in the Windows 10 environment, the process is virtually identical on all versions of the Microsoft Windows operating system).

Screenshot of websites added to Windows hosts file:

Tro Ransomware adding websites to Windows Hosts file

Krusop ransomware removal:

Instant automatic removal of Krusop virus: Manual threat removal might be a lengthy and complicated process that requires advanced computer skills. Spyhunter is a professional automatic malware removal tool that is recommended to get rid of Krusop virus. Download it by clicking the button below:
▼ DOWNLOAD Spyhunter By downloading any software listed on this website you agree to our Privacy Policy and Terms of Use. Free scanner checks if your computer is infected. To remove malware, you have to purchase the full version of Spyhunter.

Quick menu:

Step 1

Windows XP and Windows 7 users: Start your computer in Safe Mode. Click Start, click Shut Down, click Restart, click OK. During your computer start process, press the F8 key on your keyboard multiple times until you see the Windows Advanced Option menu, and then select Safe Mode with Networking from the list.

Safe Mode with Networking

Video showing how to start Windows 7 in "Safe Mode with Networking":

Windows 8 users: Start Windows 8 is Safe Mode with Networking - Go to Windows 8 Start Screen, type Advanced, in the search results select Settings. Click Advanced startup options, in the opened "General PC Settings" window, select Advanced startup. Click the "Restart now" button. Your computer will now restart into the "Advanced Startup options menu". Click the "Troubleshoot" button, and then click the "Advanced options" button. In the advanced option screen, click "Startup settings". Click the "Restart" button. Your PC will restart into the Startup Settings screen. Press F5 to boot in Safe Mode with Networking.

Windows 8 Safe Mode with networking

Video showing how to start Windows 8 in "Safe Mode with Networking":

Windows 10 users: Click the Windows logo and select the Power icon. In the opened menu click "Restart" while holding "Shift" button on your keyboard. In the "choose an option" window click on the "Troubleshoot", next select "Advanced options". In the advanced options menu select "Startup Settings" and click on the "Restart" button. In the following window you should click the "F5" button on your keyboard. This will restart your operating system in safe mode with networking.

windows 10 safe mode with networking

Video showing how to start Windows 10 in "Safe Mode with Networking":

Step 2

Log in to the account infected with the Krusop virus. Start your Internet browser and download a legitimate anti-spyware program. Update the anti-spyware software and start a full system scan. Remove all entries detected.

If you cannot start your computer in Safe Mode with Networking, try performing a System Restore.

Video showing how to remove ransomware virus using "Safe Mode with Command Prompt" and "System Restore":

1. During your computer start process, press the F8 key on your keyboard multiple times until the Windows Advanced Options menu appears, and then select Safe Mode with Command Prompt from the list and press ENTER.

Boot your computer in Safe Mode with Command Prompt

2. When Command Prompt mode loads, enter the following line: cd restore and press ENTER.

system restore using command prompt type cd restore

3. Next, type this line: rstrui.exe and press ENTER.

system restore using command prompt rstrui.exe

4. In the opened window, click "Next".

restore system files and settings

5. Select one of the available Restore Points and click "Next" (this will restore your computer system to an earlier time and date, prior to the Krusop ransomware virus infiltrating your PC).

select a restore point

6. In the opened window, click "Yes".

run system restore

7. After restoring your computer to a previous date, download and scan your PC with recommended malware removal software to eliminate any remaining Krusop ransomware files.

To restore individual files encrypted by this ransomware, try using Windows Previous Versions feature. This method is only effective if the System Restore function was enabled on an infected operating system. Note that some variants of Krusop are known to remove Shadow Volume Copies of the files, so this method may not work on all computers.

To restore a file, right-click over it, go into Properties, and select the Previous Versions tab. If the relevant file has a Restore Point, select it and click the "Restore" button.

Restoring files encrypted by CryptoDefense

If you cannot start your computer in Safe Mode with Networking (or with Command Prompt), boot your computer using a rescue disk. Some variants of ransomware disable Safe Mode making its removal complicated. For this step, you require access to another computer.

To regain control of the files encrypted by Krusop, you can also try using a program called Shadow Explorer. More information on how to use this program is available here.

shadow explorer screenshot

To protect your computer from file encryption ransomware such as this, use reputable antivirus and anti-spyware programs. As an extra protection method, you can use programs called HitmanPro.Alert and EasySync CryptoMonitor, which artificially implant group policy objects into the registry to block rogue programs such as Krusop ransomware.

Note that Windows 10 Fall Creators Update includes "Controlled Folder Access" feature that blocks ransomware attempts to encrypt your files. By default this feature automatically protects files stored in Documents, Pictures, Videos, Music, Favorites as well as Desktop folders.

Controll Folder Access

Windows 10 users should install this update to protect their data from ransomware attacks. Here's more information on how to get this update and add additional protection layer from ransomware infections.

HitmanPro.Alert CryptoGuard - detects encryption of files and neutralises any attempts without need for user-intervention:

hitmanproalert ransomware prevention application

Malwarebytes Anti-Ransomware Beta uses advanced proactive technology that monitors ransomware activity and terminates it immediately - before reaching users' files:

malwarebytes anti-ransomware

  • The best way to avoid damage from ransomware infections is to maintain regular up-to-date backups. More information on online backup solutions and data recovery software Here.

Other tools known to remove Krusop ransomware:

About the author:

Tomas Meskauskas

Tomas Meskauskas - expert security researcher, professional malware analyst.

I am passionate about computer security and technology. I have an experience of over 10 years working in various companies related to computer technical issue solving and Internet security. I have been working as an author and editor for pcrisk.com since 2010. Follow me on Twitter and LinkedIn to stay informed about the latest online security threats. Contact Tomas Meskauskas.

PCrisk security portal is brought by a company RCS LT. Joined forces of security researchers help educate computer users about the latest online security threats. More information about the company RCS LT.

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Malware activity

Global virus and spyware activity level today:

Medium threat activity
Medium

Increased attack rate of infections detected within the last 24 hours.

QR Code
Krusop virus QR code
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Platform: Windows

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