Remove MW_ IN FILES.txt or KK_ IN YOUR DOCUMENTS.txt virus (Guide)

If your pictures, videos and documents have an MW_ or KK_ prefix at the end and have a MW_ IN FILES.txt or KK_ IN YOUR DOCUMENTS.txt document on your desktop, then your computer has been infected with the Trojan-Ransom.NSIS.ONION.air ransomware.
Trojan-Ransom.NSIS.ONION.air is a file-encrypting ransomware, which will encrypt the personal documents found on victim’s computer using RSA-2048 key (AES CBC 256-bit encryption algorithm). Trojan-Ransom.NSIS.ONION.air then displays a message which offers to decrypt the data if a payment of 1 BTC (Bitcoins) is made within 96 hours, otherwise the data will be destroyed.

1. How did the MW_ or KK_ prefix virus got on my computer?
2. What is MW_ or KK_ prefix Ransomware?
3. Is my computer infected with MW_ or KK_ prefix virus?
4. Is it possible to decrypt files encrypted by MW_ or KK_ prefix?
5. How to remove the MW_ IN FILES.txt or KK_ IN YOUR DOCUMENTS.txt and MW_ or KK_ prefix ransomware (Virus Removal Guide)

1. How did the MW_ or KK_ prefixvirus got on my computer?

The MW_ or KK_ ransomware is distributed through several means. Malicious websites, or legitimate websites that have been hacked, can infect your machine through exploit kits that use vulnerabilities on your computer to install this Trojan without your permission of knowledge.

Another method used to propagate this type of malware is spam email containing infected attachments or links to malicious websites. Cyber-criminals spam out an email, with forged header information, tricking you into believing that it is from a shipping company like DHL or FedEx. The email tells you that they tried to deliver a package to you, but failed for some reason. Sometimes the emails claim to be notifications of a shipment you have made. Either way, you can’t resist being curious as to what the email is referring to – and open the attached file (or click on a link embedded inside the email). And with that, your computer is infected with the MW_ or KK_ (Trojan-Ransom.NSIS.ONION.air) ransowmare

The threat may also be downloaded manually by tricking the user into thinking they are installing a useful piece of software, for instance a bogus update for Adobe Flash Player or another piece of software.

2. What is MW_ or KK_ prefix Ransomware?

The MW_ or KK_ prefix is part of the Trojan-Ransom.NSIS.ONION.air ransomware program which targets all versions of Windows including Windows XP, Windows Vista, Windows 7, and Windows 8. This infection is notable due to how it encrypts the user’s files – namely, it uses AES-265 and RSA encryption method – in order to ensure that the affected user has no choice but to purchase the private key.

When MW_ or KK_ prefix ransomware is first installed on your computer it will create a random named executable in the %AppData% or %LocalAppData% folder. This executable will be launched and begin to scan all the drive letters on your computer for data files to encrypt.
Trojan-Ransom.NSIS.ONION.air ransomware searches for files with certain file prefixs to encrypt. The files it encrypts include important productivity documents and files such as .doc, .docx, .xls, .pdf, among others. When these files are detected, this infection will append a new MW_ or KK_ prefix to the file name.
Files targeted are those commonly found on most PCs today; a list of file prefixs for targeted files include:

.sql, .mp4, .7z, .rar, .m4a, .wma, .avi, .wmv, .csv, .d3dbsp, .zip, .sie, .sum, .ibank, .t13, .t12, .qdf, .gdb, .tax, .pkpass, .bc6, .bc7, .bkp, .qic, .bkf, .sidn, .sidd, .mddata, .itl, .itdb, .icxs, .hvpl, .hplg, .hkdb, .mdbackup, .syncdb, .gho, .cas, .svg, .map, .wmo, .itm, .sb, .fos, .mov, .vdf, .ztmp, .sis, .sid, .ncf, .menu, .layout, .dmp, .blob, .esm, .vcf, .vtf, .dazip, .fpk, .mlx, .kf, .iwd, .vpk, .tor, .psk, .rim, .w3x, .fsh, .ntl, .arch00, .lvl, .snx, .cfr, .ff, .vpp_pc, .lrf, .m2, .mcmeta, .vfs0, .mpqge, .kdb, .db0, .dba, .rofl, .hkx, .bar, .upk, .das, .iwi, .litemod, .asset, .forge, .ltx, .bsa, .apk, .re4, .sav, .lbf, .slm, .bik, .epk, .rgss3a, .pak, .big, wallet, .wotreplay, .xxx, .desc, .py, .m3u, .flv, .js, .css, .rb, .png, .jpeg, .txt, .p7c, .p7b, .p12, .pfx, .pem, .crt, .cer, .der, .x3f, .srw, .pef, .ptx, .r3d, .rw2, .rwl, .raw, .raf, .orf, .nrw, .mrwref, .mef, .erf, .kdc, .dcr, .cr2, .crw, .bay, .sr2, .srf, .arw, .3fr, .dng, .jpe, .jpg, .cdr, .indd, .ai, .eps, .pdf, .pdd, .psd, .dbf, .mdf, .wb2, .rtf, .wpd, .dxg, .xf, .dwg, .pst, .accdb, .mdb, .pptm, .pptx, .ppt, .xlk, .xlsb, .xlsm, .xlsx, .xls, .wps, .docm, .docx, .doc, .odb, .odc, .odm, .odp, .ods, .odt

While encrypting your files, this ransomware also create a MW_ IN FILES.txt or KK_ IN YOUR DOCUMENTS.txt text file ransom note in each folder that a file has been encrypted and on the Windows desktop. The ransomware will also change your Windows desktop wallpaper to MW_ IN FILES.bmp.
Both the wallpaper and the text ransom note will contain the same information on how to access the payment site and get your files back.
When you go to the URLs listed in the ransom note you will be taken to a TOR site where you can learn how much your ransom is and how to make the payment.

The MW_ or KK_ ransomware will also hijack your .EXE prefixs so that when you launch an executable it will attempt to delete the Shadow Volume Copies that are on the affected computer. It does this because you can use shadow volume copies to restore your encrypted files. Once the infection has successfully deleted your shadow volume copies, it will restore your exe prefixs back to the Windows defaults.

When it has finished encrypting your data files it will then show the MW_ or KK_ prefix at the end of your personal documents, and a screen demanding a ransom of 0.7 BTC in order to decrypt your files. It also states that you must pay this ransom within 96 hours or the private encryption key will be destroyed on the developer’s servers.

3. Is my computer infected with MW_ or KK_ prefix virus?

If your computer is infected with the MW_ or KK_ ransomware will display a black MW_ IN FILES.bmp wallpaper that covers the entire desktop. A MW_ IN FILES.txt or KK_ IN YOUR DOCUMENTS.txt text file will be placed on your desktop. Both files contain instruction on how or recover the encrypted files.

The messages displayed by this ransomware infection can be localized depending on the user’s location, with text written in the appropriate language.
This the message that the MW_ or KK_ ransomware may display:

Good day. Your computer has been locked by ransomware, your personal files are encrypted and you have unfortunately “lost” all your pictures,
files and documents on the computer. Your important files encryption produced on this computer: videos, photos, documents, etc.
Encryption was produced using unique public key RSA-1024 generated for this computer. To decrypt files you need to obtain the private key.
All encrypted files contain MW_
Your number: [removed] To obtain the program for this computer, which will decrypt all files, you need to pay
3 bitcoins on our bitcoin address [removed] (today 1 bitcoin was 260 USA dollars). Only we and you know about this bitcoin address.
You can check bitcoin balanse here – https://www.blockchain.info/address/[removed] After payment send us your number on our mail ttk@ruggedinbox.com and we will send you decryption tool (you need only run it and all files will be decrypted during 1…3 hours)
Before payment you can send us one small file (100..500 kilobytes) and we will decrypt it – it’s your garantee that we have decryption tool. And send us your number with attached file
We dont know who are you. All what we need – it’s some money.
Don’t panic if we don’t answer you during 24 hours. It means that we didn’t received your letter (for example if you use hotmail.com or outlook.com
it can block letter, SO DON’T USE HOTMAIL.COM AND OUTLOOK.COM. You need register your mail account in www. ruggedinbox .com (it will takes 1..2 minutes) and write us again)
You can use one of that bitcoin exchangers for transfering bitcoin.

4. Is it possible to decrypt files encrypted by MW_ or KK_ ransomware?

No, at this time it’s not possible.

The MW_ or KK_ ransomware is notable due to how it encrypts the user’s files – namely, it uses AES-265 and RSA encryption method – in order to ensure that the affected user has no choice but to purchase the private key. The RSA public key can only be decrypted with its corresponding private key. Since the AES key is hidden using RSA encryption and the RSA private key is not available, decrypting the files is not feasible as of this writing.
Brute forcing the decryption key is not realistic due to the length of time required to break an AES encryption key.

Because the needed private key to unlock the encrypted file is only available through the cyber criminals, victims may be tempted to purchase it and pay the exorbitant fee. However, doing so may encourage these bad guys to continue and even expand their operations. We strongly suggest that you do not send any money to these cyber criminals, and instead adress to the law enforcement agency in your country to report this attack.

5. How to remove the MW_ or KK_ ransomware (Virus Removal Guide)

This page is a comprehensive guide, which will remove the MW_ or KK_ prefix infection from your computer, however we cannot guarantee that your personal files will be recovered. We cannot be held responsible for losing the documents during this removal process.

A. Remove MW_ IN FILES.txt or KK_ IN YOUR DOCUMENTS.txt and MW_ or KK_ prefix ransomware from your computer

Malwarebytes and HitmanPro can detect and remove this infection, but these programs cannot recover your encrypted files due to the nature of asymmetric encryption, which requires a private key to decrypt files encrypted with the public key.

STEP 1: Remove MW_ IN FILES.txt or KK_ IN YOUR DOCUMENTS.txt and MW_ or KK_ prefix virus with Malwarebytes Anti-Malware Free

Malwarebytes Anti-Malware Free uses industry-leading technology to detect and remove all traces of malware, including worms, Trojans, rootkits, rogues, dialers, spyware, and more.
It is important to note that Malwarebytes Anti-Malware works well and should run alongside antivirus software without conflicts.

1. You can download download Malwarebytes Anti-Malware from the below link.
   MALWAREBYTES ANTI-MALWARE DOWNLOAD LINK (This link will open a new web page from where you can download “Malwarebytes Anti-Malware Free”)
2. Once downloaded, close all programs, then double-click on the icon on your desktop named “mbam-setup” to start the installation of Malwarebytes Anti-Malware.
   
   You may be presented with a User Account Control dialog asking you if you want to run this file. If this happens, you should click “Yes” to continue with the installation.
3. When the installation begins, you will see the Malwarebytes Anti-Malware Setup Wizard which will guide you through the installation process.
   
   To install Malwarebytes Anti-Malware on your machine, keep following the prompts by clicking the “Next” button.
   
4. Once installed, Malwarebytes Anti-Malware will automatically start and you will see a message stating that you should update the program, and that a scan has never been run on your system. To start a system scan you can click on the “Scan Now” button.
   
5. Malwarebytes Anti-Malware will now start scanning your computer for the MW_ or KK_ virus. When Malwarebytes Anti-Malware is scanning it will look like the image below.
   
6. When the scan has completed, you will now be presented with a screen showing you the malware infections that Malwarebytes Anti-Malware has detected. To remove the malicious programs that Malwarebytes Anti-malware has found, click on the “Remove Seletected” button.
   
   Please note that the infections found may be different than what is shown in the image.
7. Malwarebytes Anti-Malware will now quarantine all the malicious files and registry keys that it has found. When removing the files, Malwarebytes Anti-Malware may require a reboot in order to remove some of them. If it displays a message stating that it needs to reboot your computer, please allow it to do so.
   
   After your computer will restart, you should open Malwarebytes Anti-Malware and perform another “Threat Scan” scan to verify that there are no remaining threats

STEP 2: Double-check for the MW_ IN FILES.txt or KK_ IN YOUR DOCUMENTS.txt and MW_ or KK_ prefix malware infection with HitmanPro

HitmanPro is a second opinion scanner, designed to rescue your computer from malware (viruses, trojans, rootkits, etc.) that have infected your computer despite all the security measures you have taken (such as anti-virus software, firewalls, etc.). HitmanPro is designed to work alongside existing security programs without any conflicts. It scans the computer quickly (less than 5 minutes) and does not slow down the computer.

1. You can download HitmanPro from the below link:
   HITMANPRO DOWNLOAD LINK (This link will open a new web page from where you can download “HitmanPro”)
2. Double-click on the file named “HitmanPro.exe” (for 32-bit versions of Windows) or “HitmanPro_x64.exe” (for 64-bit versions of Windows). When the program starts you will be presented with the start screen as shown below.
   
   Click on the “Next” button, to install HitmanPro on your computer.
   
3. HitmanPro will now begin to scan your computer for MW_ or KK_ malicious files.
   
4. When it has finished it will display a list of all the malware that the program found as shown in the image below. Click on the “Next” button, to remove MW_ or KK_ prefix virus.
   
5. Click on the “Activate free license” button to begin the free 30 days trial, and remove all the malicious files from your computer.
   

B. How (try) to restore your files encrypted by MW_ or KK_ prefix ransomware

In some cases, it may be possible to recover previous versions of the encrypted files using System Restore or other recovery software used to obtain “shadow copies” of files.

Option 1: Restore your files encrypted by MW_ or KK_ ransomware with ShadowExplorer

The MW_ or KK_ ransomware will attempt to delete all shadow copies when you first start any executable on your computer after becoming infected. Thankfully, the infection is not always able to remove the shadow copies, so you should continue to try restoring your files using this method.

1. You can download ShadowExplorer from the below link:
   SHADOW EXPLORER DOWNLOAD LINK (This link will open a new web page from where you can download “ShadowExplorer”)
2. Once you have downloaded and installed ShadowExplorer, you can follow the below video guide on how to restore your files while using this program.
   

Alternatively, you can use the System Restore to try to recover the encrypted documents.

Option 2: Restore your files encrypted by MW_ or KK_ ransomware with File Recovery Software

When MW_ or KK_ malware encrypts a file it first makes a copy of it, encrypts the copy, and then deletes the original. Due to this you can use file recovery software such as:

• Recuva
  You can follow the below guide on how to use Recuva:
  
• EaseUS Data Recovery Wizard Free
• R-Studio