.Koti file extension ransomware (Koti File Recovery Guide)

What is Koti file extension

.Koti file extension is a file extension that is used by the 226th version of the STOP ransomware to mark files that have been encrypted. Koti ransomware is a malware that is created to encrypt the victim’s files, and then demand a ransom for decrypting them. Fortunately, there is a free Koti File Decrypt Tool called STOP Djvu Decryptor that can decrypt encrypted files in some cases. In addition to this decryptor, there are several more methods that can help restore the contents of encrypted files. Read more about Koti File Decrypt Tool, as well as how to remove Koti ransomware, how to recover .Koti files and how to protect the computer from such ransomware below.

Screenshot of files encrypted by Koti ransomware (‘.koti’ file extension)

What is Koti ransomware

Koti ransomware is new version of STOP (Djvu) ransomware. According to security researchers, this version is not much different from previous versions of the STOP ransomware, such as Mzlq and Sqpc, which were discovered earlier. The Koti ransomware is spread by websites offering to download freeware, key generators, activators, cracked games, torrents and so on.

Upon execution, Koti creates a folder in the Windows system directory where it places a copy of itself and changes some Windows settings so that it starts up every time the computer is restarted or turned on. The virus collects information about the victim’s computer and then tries to establish a connection with its command server (C&C). If the connection has been established, then it sends information about the infected computer to the server, and in response receives the encryption key (the so-called ‘online key’) and additional commands and malware that must be executed on the victim’s computer. If the virus could not establish a connection with its command server, then it uses a fixed key (the so-called ‘offline key’).

The Koti ransomware encrypts files using a strong encryption algorithm and a key (‘offline key’ or ‘online key’, as described above). The virus tries to encrypt as many files as possible, for this it only encrypts the first 154kb of the contents of each file and thus significantly speeds up the encryption process. Koti has the ability to encrypt files on all drives connected to the computer: internal hard drives, flash USB disks, network storage, and so on. It skips without encryption: files located in the Windows system directories, files with the extension .ini, .bat, .dll, .lnk, .sys and files with the name ‘_readme.txt’. The remaining files located on the victim’s computer can be encrypted. For example, the following file types may be the target of ransomware attack:

.xlsm, .cas, .dba, .wps, .xlsx, .ppt, .iwi, .wbc, .xxx, .mef, .wm, .dazip, .kdb, .y, .hplg, .wbm, .wp6, .jpe, .wp5, .forge, .qic, .sidd, .mov, .wdb, .zabw, .txt, .xdb, .zif, .itdb, .wmd, .vcf, .p7c, .m3u, .wpg, .pef, wallet, .qdf, .3fr, .zip, .xyw, .eps, .hkdb, .zip, .srf, .m2, .jpg, .cr2, .zi, .xar, .mdf, .wpd, .xf, .wp, .orf, .wgz, .map, .itl, .dng, .wb2, .sav, .0, .sql, .rgss3a, .xwp, .cer, .wbk, .vpk, .3ds, .mpqge, .xls, .wma, .t12, .xbplate, .sb, .wbz, .pptm, .csv, .cdr, .sr2, .mcmeta, .wpb, .blob, .esm, .fsh, .xx, .xlsm, .hkx, .x, .lrf, .avi, .gho, .mlx, .dcr, .wri, .mdb, .jpeg, .docm, .odc, .7z, .slm, .indd, .psd, .xlsx, .odp, .odt, .yal, .x3f, .zdb, .lbf, .webp, .dxg, .ff, .ods, .vdf, .epk, .xmind, .ltx, .rtf, .wma, .wire, .wsh, .pptx, .accdb, .dbf, .docx, .lvl, .ibank, .wot, .x3d, .p7b, .flv, .bik, .crw, .sis, .z3d, .hvpl, .xbdoc, .pfx, .syncdb, .wotreplay, .gdb, .wmf, .yml, .cfr, .pkpass, .raf, .mrwref, .wcf, .psk, .bay, .itm, .pdf, .icxs, .w3x, .bsa, .ptx, .rb, .rar, .pst, .sie, .ai, .mdbackup, .wp4, .wp7, .svg, .kdc, .d3dbsp, .nrw, .ncf, .db0, .arch00, .xlsb, .rwl, .menu, .ws, .wsc, .dwg, .srw, .wmv, .zw, .zdc, .vtf, .rw2, .wmo, .xml, .upk, .css, .wpd, .wpl, .xy3, .erf, .ysp, .xld, .pak, .wpw, .xpm, .3dm, .litemod, .py, .wbd, .desc

Koti encrypts file-by-file. Each file that has been encrypted will be renamed, the .koti extension will be added at the end of its name. Thus, it marks all encrypted files. In every directory where there is at least one encrypted file, the virus places a file named ‘_readme.txt’. The file contains a message from the Koti authors. An example of the contents of this file is given below.

Screenshot of the contents of ‘_readme.txt’ file (Koti ransom note)

This message says that all files on the computer are encrypted and the only way to decrypt them is to buy a key and a decryptor from the authors of the Koti ransomware. That is, criminals demand a ransom for unlocking the victim’s files. The size of the ransom is $980, but if the victim is ready to pay the ransom within 72 hours, then its size is halved to $490. Attackers offer victims to verify that encrypted files can be decrypted. To do this, the victim must send them a small file to one of the email addresses specified in the ‘_readme.txt’ file. Of course, it is obvious that a single decrypted file cannot guarantee that after paying the ransom, the criminals will provide the victim with a working key and decryptor.

The full text of the Koti ransom note is

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:
https://we.tl/t-EEHXgjySek
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:
helpmanager@mail.ch

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

Your personal ID:
0226yiuduy6S5dbQzou4YCQGWMhQnYUmmzNP6cr4msBmV2AwESnrt1

Threat Summary

How to remove Koti ransomware, Recover, Decrypt .koti files

Security researchers confirm the words of the authors of the Koti ransomware. All files with the extension ‘.Koti’ are encrypted and thus cannot be read and used. The only way to decrypt them is to use the key and the decryptor. Fortunately, there is some good news. As we already reported above, the Koti virus belongs to the STOP ransomware family, which means that you can use a Koti File Decrypt Tool called “STOP Djvu decryptor” that is created by Emsisoft to decrypt the encrypted files for free. Even if the decryptor does not help, there are some alternative ways that can help restore the contents of the encrypted files. To learn more about decrypting files, simply scroll down to section ‘How to decrypt .koti files’. Read the entire manual carefully. To make it easier for you to follow the instructions, we recommend that you print it or open it on your smartphone.

1. How to remove Koti ransomware
2. How to decrypt .koti files
3. How to restore .koti files
4. How to protect your personal computer from Koti ransomware

How to remove Koti ransomware

Finding and removing ransomware components manually is very difficult, so we recommend using free malware removal tools. Moreover, it is desirable to use not one, but several utilities. Even if it seems to you that there is no ransomware on the computer, it does not mean anything. The virus may start encrypting the files again the next time you turn on or restart the computer. You must be completely sure that Koti has been removed, and also that there is no other malware on the computer. Below we provide a list of recommended tools with brief instructions.

Remove Koti ransomware virus with Zemana Free

Zemana Anti-Malware (ZAM) is a program which is used for ransomware, spyware, trojans, malware, adware, worms and other security threats removal. This malwar removal tool is one of the most efficient anti-malware utilities. It helps in crypto virus removal and and defends all other types of malicious software. One of the biggest advantages of using Zemana Anti Malware is that is easy to use and is free. Also, it constantly keeps updating its virus/malware signatures DB. Let’s see how to install and scan your machine with Zemana Anti Malware in order to remove Koti ransomware virus from your computer.

Installing the Zemana is simple. First you’ll need to download Zemana by clicking on the link below.

Zemana AntiMalware
164029 downloads
Author: Zemana Ltd
Category: Security tools
Update: July 16, 2019

Once downloading is done, close all software and windows on your PC. Double-click the setup file called Zemana.AntiMalware.Setup. If the “User Account Control” prompt pops up as on the image below, click the “Yes” button.

It will open the “Setup wizard” that will help you install Zemana on your machine. Follow the prompts and do not make any changes to default settings.

Once install is complete successfully, Zemana Free will automatically start and you can see its main screen as shown below.

Now click the “Scan” button to begin checking your PC for the Koti ransomware related folders,files and registry keys. A scan can take anywhere from 10 to 30 minutes, depending on the number of files on your PC system and the speed of your machine. While the Zemana Anti Malware (ZAM) utility is checking, you can see number of objects it has identified as being affected by malware.

When Zemana AntiMalware (ZAM) has completed scanning, you can check all threats detected on your computer. You may remove items (move to Quarantine) by simply click “Next” button. The Zemana Anti-Malware will delete Koti ransomware, other malware, worms and trojans. Once the process is finished, you may be prompted to restart the computer.

Remove Koti ransomware with MalwareBytes

You can remove Koti automatically through the use of MalwareBytes Anti Malware (MBAM). We recommend this free malware removal utility because it may easily delete ransomware, adware software, malicious software and other unwanted software with all their components such as files, folders and registry entries.

Download MalwareBytes Free by clicking on the following link. Save it to your Desktop.

Malwarebytes Anti-malware
326382 downloads
Author: Malwarebytes
Category: Security tools
Update: April 15, 2020

Once downloading is done, run it and follow the prompts. Once installed, the MalwareBytes will try to update itself and when this procedure is done, click the “Scan” button to begin checking your computer for the Koti ransomware virus, other kinds of potential threats such as malware and trojans. This process can take some time, so please be patient. While the MalwareBytes Free program is scanning, you can see how many objects it has identified as threat. Next, you need to click “Quarantine” button.

The MalwareBytes Anti-Malware is a free program that you can use to uninstall all detected folders, files, services, registry entries and so on. To learn more about this malicious software removal utility, we suggest you to read and follow the guidance or the video guide below.

If the problem with Koti virus is still remained

If you have already used some malware removal tools, they found and removed malicious software, then in order to be 100% sure that the computer no longer has Koti crypto virus, we recommend using the Kaspersky virus removal tool (KVRT). This utility, as its name suggests, is created by the Kaspersky lab and uses the core of the Kaspersky Antivirus. Unlike the Kaspersky Antivirus, KVRT has a smaller size and, most importantly, it can work together with an already installed antivirus software. This utility has great capabilities and therefore we recommend using KVRT in the last turn to be sure that the Koti crypto virus has been removed.

Download Kaspersky virus removal tool (KVRT) on your Windows Desktop from the link below.

Kaspersky virus removal tool
129055 downloads
Author: Kaspersky® lab
Category: Security tools
Update: March 5, 2018

After the download is done, double-click on the KVRT icon. Once initialization procedure is complete, you will see the KVRT screen as shown in the following example.

Click Change Parameters and set a check near all your drives. Click OK to close the Parameters window. Next click Start scan button . KVRT tool will start scanning the whole personal computer to find out Koti ransomware and other known infections. This process can take some time, so please be patient.

Once Kaspersky virus removal tool has completed scanning your computer, Kaspersky virus removal tool will open a screen which contains a list of malware that has been found like below.

In order to remove all threats, simply press on Continue to start a cleaning task.

How to decrypt .koti files

As we already reported above, files with .koti extension are files that have been encrypted by the Koti ransomware. Their contents will remain locked until decrypted using the decryptor and the key. Fortunately, there is a free Koti File Decrypt Tool that can decrypt .koti files. Below we provide instructions on where to download and how to use this decryptor.

Koti File Decrypt Tool (STOP Djvu decryptor)

To decrypt .koti files, use Koti File Decrypt Tool

• Download Koti File Decrypt Tool from the following link.
  STOP Djvu decryptor
• Scroll down to ‘New Djvu ransomware’ section.
• Click the download link and save the decrypt_STOPDjvu.exe file to your desktop.
• Run decrypt_STOPDjvu.exe, read the license terms and instructions.
• On the ‘Decryptor’ tab, using the ‘Add a folder’ button, add the directory or disk where the encrypted files are located.
• Click the ‘Decrypt’ button.

Koti File Decypt Tool is a free software that can decrypt files that were encrypted with an offline key, as Emsisoft found a way to determine this key. Unfortunately, files encrypted with an online key cannot yet be decrypted. The online key is unique to each infected computer, and at the moment there is no way to obtain this key. Of course, criminals have this key, but we do not think that paying a ransom is a way to decrypt .koti files. In the case when the files are encrypted with an online key, there is a chance to restore the encrypted files using alternative methods, which are described below.

How to find out which key was used to encrypt files

Below we will demonstrate how to find out the type of key with which files were encrypted. This is very important, since knowing the type of key you can understand if you can decrypt .koti files for free using the Koti File Decypt Tool. We recommend using the second method, as it is more accurate.

Personal ID is highlighted here

How to find out the type of a key using ‘_readme.txt’ file

• Open the ransom demand message (‘_readme.txt’ file).
• Scroll down to the end of the file.
• There you will see a line with the text ‘Your personal ID’.
• Below is a line of characters that starts with ‘0226’ – this is your personal id.

How to find out the type of a key using ‘PersonalID.txt’ file

• Open disk C.
• Open directory ‘SystemID’.
• Open file named ‘PersonalID.txt’. This file lists ‘Personal ID’s that match the keys that the virus used to encrypt files.

This video step-by-step guide will demonstrate How to find out the type of a key.

The ‘Personal ID’ is not a key, it is an identifier related to a key that was used to encrypt files. If the ID ends with ‘t1’, then the files are encrypted with an offline key. If the ID does not end with ‘t1’, Koti virus used an online key. If you could not figure out how to determine which key was used to encrypt files, then we can help. Just write a request here or in the comments below.

Koti File Decypt Tool : No key for New Variant online ID

If, when you try to decrypt .koti files, the Koti File Decypt Tool reports No key for New Variant online ID, then this means that your files are encrypted with an ‘online key’ and their decryption is impossible, since only the Koti authors have the key necessary for decryption. In this case, you need to use alternative methods listed below to restore the contents of encrypted files.

Koti File Decypt Tool : No key for New Variant offline ID

If during decryption of .koti files the Koti File Decypt Tool reports No key for New Variant offline ID, then this means the following: your files are encrypted with an ‘offline key’, but the key itself has not yet been found by security researchers, in this case, you need to be patient and wait a while, in addition, you can also use alternative ways for recovering encrypted data. It is impossible to say exactly when the ‘offline key’ will be determined. Sometimes it takes several days, sometimes more. We recommend that you try to decrypt .koti files from time to time. You can also use alternative ways listed below for recovering encrypted data.

How to restore .koti files

As we mentioned above, in addition to using the free decryptor, there are several more methods for recovering encrypted files. These methods do not require the use of a decryptor and a key, and therefore are suitable for all cases when the virus used an online key, and for the case when the virus used an offline key. It is very important to check your computer for malware before you try to recover encrypted files. You must be 100% sure that Koti virus is completely removed. To scan your computer for ransomware, use free malware removal tools.

Run ShadowExplorer to recover .koti files

The Microsoft Windows has a feature called ‘Shadow Volume Copies’ that can help you to recover .koti files encrypted by the ransomware. A small tool called ShadowExplorer will allow you to easily access the Shadow copies and restore the encrypted files to their original state. Unfortunately, the ransomware can delete these Shadow copies before it starts encrypting files. Therefore, if ShadowExplorer did not help you, then try another method, which is given below.

Please go to the following link to download the latest version of ShadowExplorer for Microsoft Windows. Save it directly to your Windows Desktop.

ShadowExplorer
438662 downloads
Author: ShadowExplorer.com
Category: Security tools
Update: September 15, 2019

Once the download is done, open a directory in which you saved it. Right click to ShadowExplorer-0.9-portable and select Extract all. Follow the prompts. Next please open the ShadowExplorerPortable folder as on the image below.

Double click ShadowExplorerPortable to run it. You will see the a window as displayed in the figure below.

In top left corner, select a Drive where encrypted personal files are stored and a latest restore point as displayed in the figure below (1 – drive, 2 – restore point).

On right panel look for a file that you want to recover, right click to it and select Export as displayed in the following example.

This video step-by-step guide will demonstrate How to recover encrypted files using Shadow Explorer.

Run PhotoRec to restore .koti files

The last chance to restore encrypted files to their original state is using data recovery tools. We recommend a program called PhotoRec. It has all the necessary functions to restore the contents of encrypted files. It helped many victims recover data when it seemed like there was no more hope.

Download PhotoRec on your Microsoft Windows Desktop from the following link.

PhotoRec
220571 downloads
Author: CGSecurity
Category: Security tools
Update: March 1, 2018

Once the download is done, open a directory in which you saved it. Right click to testdisk-7.0.win and select Extract all. Follow the prompts. Next please open the testdisk-7.0 folder as displayed in the figure below.

Double click on qphotorec_win to run PhotoRec for MS Windows. It’ll show a screen as displayed below.

Choose a drive to recover as displayed in the following example.

You will see a list of available partitions. Select a partition that holds encrypted files as displayed on the screen below.

Click File Formats button and specify file types to restore. You can to enable or disable the restore of certain file types. When this is finished, press OK button.

Next, click Browse button to select where recovered documents, photos and music should be written, then press Search.

Count of restored files is updated in real time. All recovered files are written in a folder that you have selected on the previous step. You can to access the files even if the recovery process is not finished.

When the restore is done, click on Quit button. Next, open the directory where recovered personal files are stored. You will see a contents as shown in the following example.

All restored files are written in recup_dir.1, recup_dir.2 … sub-directories. If you’re looking for a specific file, then you can to sort your recovered files by extension and/or date/time.

This video step-by-step guide will demonstrate How to recover encrypted files using PhotoRec.

How to protect your personal computer from Koti ransomware

Most antivirus software already have built-in protection system against the crypto malware. Therefore, if your computer does not have an antivirus application, make sure you install it. As an extra protection, run the HitmanPro.Alert. HitmanPro.Alert is a small security tool. It can check the system integrity and alerts you when critical system functions are affected by malware. HitmanPro.Alert can detect, remove, and reverse ransomware effects.

Download HitmanPro Alert by clicking on the link below. Save it to your Desktop.

HitmanPro.Alert
6826 downloads
Author: Sophos
Category: Security tools
Update: March 6, 2019

When the download is finished, open the directory in which you saved it. You will see an icon like below.

Double click the HitmanPro Alert desktop icon. When the utility is started, you’ll be shown a window where you can select a level of protection, as displayed on the image below.

Now click the Install button to activate the protection.

To sum up

This guide was created to help all victims of Koti ransomware virus. We tried to give answers to the following questions: how to remove ransomware; how to decrypt .koti files; how to recover files, if Koti File Decrypt Tool does not help; what is an online key and what is an offline key. We hope that the information presented in this manual has helped you.

If you have questions, then write to us, leaving a comment below. If you need more help with Koti related issues, go to here.