Koti ransomware removal instructions
What is Koti?
Koti is a piece of malicious software, which is part of the Djvu ransomware family. It is designed to encrypt the files of infected systems in order to make ransom demands. As this ransomware encrypts, all of the affected files are appended with the ".koti" extension. For example, a file originally titled something like "1.jpg" would appear as "1.jpg.koti" - after encryption. Following the end of this process, a text file - "_readme.txt" - is created dropped into every compromised folder.
The ransom note in "_readme.txt" reassures victims that it is possible to recover their data. Users are informed that their files have been encrypted with strongest encryption and unique key. The sole method of restoring them is by purchasing decryption keys and software from the cyber criminals behind Koti. Before paying, victims can test decryption by sending one encrypted non-valuable file via email. The decryption of said file will serve as proof that recovery is viable. The size of the ransom is listed as 980 USD. If contact with the criminals is established within the first 72 hours, a 50% percent discount will be available - thereby, halving the price to 490 USD. Should no response arrive within 6 hours, users are instructed to inspect their "Spam/Junk" email folders, as the reply may have gotten sent to this part of their inbox. Unfortunately, in most cases of ransomware infections, without involving the cyber criminals responsible - decryption is impossible. It might be, if the malware has significant flaws and/or is still in development. Regardless, it is expressly advised against meeting the ransom demands. There no guarantees that the criminals will hold true to their word, and often - they do not. Therefore, despite paying - it is common for victims not to receive the necessary tools to decrypt their data. To prevent Koti ransomware from encrypting more files - it must be removed from the operating system. However, removal will not restore already compromised data. The only solution is recovering the files from a backup, if one was made before the infection and was stored in a different location.
Screenshot of a message encouraging users to pay a ransom to decrypt their compromised data:
Ransomware operates by encrypting data and demanding payment for the decryption tools/software. ZoNiSoNaL, QolkuzNbVcG and Zeronine are a few examples of malicious programs within this category. These programs/infections are not identical, the main differences between them are: the cryptographic algorithm they use (symmetric or asymmetric) and the ransom size. The demanded sums typically range from three to four digits in USD. Digital currencies (primarily, cryptocurrencies) are used for the payments, due to transactions of them being difficult/impossible to trace. To protect data safety, it is recommended to keep backups in remote servers and/or unplugged storage devices (ideally, in multiple separate locations).
How did ransomware infect my computer?
|Threat Type||Ransomware, Crypto Virus, Files locker|
|Encrypted Files Extension||.koti|
|Ransom Demanding Message||_readme.txt|
|Ransom Amount||$980 or $490|
|Cyber Criminal Contactemail@example.com and firstname.lastname@example.org|
|Detection Names||Avast (Win32:CoinminerX-gen [Trj]), BitDefender (Trojan.GenericKDZ.67221), ESET-NOD32 (A Variant Of Win32/Kryptik.HDKV), Kaspersky (Hoax.Win32.ArchSMS.cqrgr), Full List Of Detections (VirusTotal)|
|Rogue Process Name||5.exe (process name may vary)|
|Symptoms||Cannot open files stored on your computer, previously functional files now have a different extension (for example, my.docx.locked). A ransom demand message is displayed on your desktop. Cyber criminals demand payment of a ransom (usually in bitcoins) to unlock your files.|
|Additional Information||This malware is designed to show a fake Windows Update window and modify the Windows "hosts" file to prevent users from accessing cyber security websites (more information below).|
|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.|
|Malware Removal (Windows)||
To eliminate possible malware infections, scan your computer with legitimate antivirus software. Our security researchers recommend using Malwarebytes.
How to protect yourself from ransomware infections?
To avoid infectious content proliferated via spam mail, it is advised not to open suspicious and/or irrelevant emails - especially and attachments or links found in them. Additionally, it is important to only use official and verified download sources. It is strongly recommended to activate and update programs with tools/functions, provided by legitimate developers. Illegal activation tools ("cracks") and third party updaters should not be used, as they are often employed to distribute malware. To ensure device integrity and user safety, it is paramount to have a dependable anti-virus/anti-spyware suite installed. This software must be kept up-to-date, used to run regular system scans and to remove detected threats. If your computer is already infected with Koti, we recommend running a scan with Malwarebytes for Windows to automatically eliminate this ransomware.
Text presented in Koti ransomware's text file ("_readme.txt"):
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:
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:
Reserve e-mail address to contact us:
Your personal ID:
Screenshot of files encrypted by Koti (".koti" extension):
Screenshot of Koti ransomware's process on Windows Task Manager ("5.exe"):
Screenshot of fake Windows update pop-up displayed during the encryption:
IMPORTANT NOTE! - As well as encrypting data, ransomware-type infections from the Djvu malware family also 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 done to prevent users from accessing malware security websites and seeking 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:
There are currently two versions of Djvu ransomware infections: old and new. The old versions were designed to encrypt data by using a hard-coded "offline key" whenever the infected machine had no internet connection or the server was timing out/not responding. Therefore, some victims were able to decrypt data using a tool developed by cyber security researcher, Michael Gillespie, however, since the encryption mechanism has been slightly changed (hence the new version, released in August, 2019), the decrypter no longer works and it is not supported anymore. If your data has been encrypted by an older version, you might be able to restore it with the another tool developed by Emsisoft and Michael Gillespie. It supports a total of 148 Djvu's variants and you can find more information, as well as download link and decryption instructions in Emsisoft's official page.
Screenshot of Djvu decryption tool by Emsisoft and Michael Gillespie:
Additionally, Emsisoft is now providing a service that allows to decrypt data (again, only if it was encrypted by Djvu variants released before August, 2019) for those victims who have a pair of the same file before and after the encryption. All victims have to do is upload a pair of original and encrypted file to Emsisoft's Djvu decryption page and download the aforementioned decryption tool (the download link will be provided after uploading files). Note that the file processing may take some time so be patient. It is also worth mentioning that the system must have an Internet connection during the entire decryption process, otherwise it will fail.
Screenshot of Emsisoft's Djvu decryption service page:
Koti ransomware removal:
Instant automatic malware removal:
Manual threat removal might be a lengthy and complicated process that requires advanced computer skills. Malwarebytes is a professional automatic malware removal tool that is recommended to get rid of malware. Download it by clicking the button below:
- What is Koti?
- STEP 1. Koti virus removal using safe mode with networking.
- STEP 2. Koti ransomware removal using System Restore.
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.
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.
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.
Video showing how to start Windows 10 in "Safe Mode with Networking":
Log in to the account infected with the Koti 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.
2. When Command Prompt mode loads, enter the following line: cd restore and press ENTER.
3. Next, type this line: rstrui.exe and press ENTER.
4. In the opened window, click "Next".
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 Koti ransomware virus infiltrating your PC).
6. In the opened window, click "Yes".
7. After restoring your computer to a previous date, download and scan your PC with recommended malware removal software to eliminate any remaining Koti 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 Koti 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.
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 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 Koti ransomware.
Note that Windows 10 Fall Creators Update includes a "Controlled Folder Access" feature that blocks ransomware attempts to encrypt your files. By default, this feature automatically protects files stored in the Documents, Pictures, Videos, Music, Favorites, and Desktop folders.
Windows 10 users should install this update to protect their data from ransomware attacks. Here is more information on how to get this update and add an additional protection layer from ransomware infections.
HitmanPro.Alert CryptoGuard - detects encryption of files and neutralises any attempts without need for user-intervention:
Malwarebytes Anti-Ransomware Beta uses advanced proactive technology that monitors ransomware activity and terminates it immediately - before reaching users' files:
- 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 Koti ransomware: