What is Ransom:Win32/StopCrypt.AK!MTB?

Ransom:Win32/StopCrypt.AK!MTB is a computer virus that blocks user from accessing their data. This threat is notorious in encrypting the target files with sophisticated method to make it unusable. The objective is to entice victims to pay the ransom demand to hackers. If remain unpaid within the given period, Ransom:Win32/StopCrypt.AK!MTB threatens to delete the unique private key that will make the encrypted files permanently useless.

Threat Behavior

Ransom:Win32/StopCrypt.AK!MTB virus normally reach its target user via spam email messages, infected software installer, botnets, drive-by-download, malicious ads, and fake software updates. Hence, it is through mass-mailing campaign that Ransom:Win32/StopCrypt.AK!MTB was able to spread quickly and more efficiently. Technically, this is called phishing email because the attackers are masquerading as legitimate company or brands and the email was designed to appear as common business messages usually related to deliveries, invoice, payment, tax, product inquiry, and other business-related matters.

The attached files where Ransom:Win32/StopCrypt.AK!MTB is embedded are often in the form of Doc, Xls, Pdf, Zip, or Html. This social engineering tactic was found to be highly effective in distributing malware due to clever used of online communication and contact references.

Once Ransom:Win32/StopCrypt.AK!MTB is inside the computer, it drops copies of itself on System folder and different directories depending on which variant is infecting the computer. As of today, there are more than 250 variants of this ransomware and here are the list of just a few.

Lyli, Copa, Kolz, Npph, Geno, Ogdo, Kasp, Boop, Vari, Oonn, Nile, Kook, Erif, Kuus, Maas, Zida, Pykw, Moba, Vawe, Usam, Tabe, Nypd, Zwer, Kkll, Nlah, Zipe, Pezi, Covm, Koti, Mzlq, Sqpc, Mpal, Qewe, Lezp, Lalo, Mpaj


The main objective of Ransom:Win32/StopCrypt.AK!MTB is to extort money from computer user and to accomplish this goal, it will execute the following task.

  • Infects the computer by exploiting different vulnerabilities especially RDP.
  • Encrypts the target files with complex algorithm using RSA Salsa20 technology.
  • Appends the virus filename to all encrypted files.
  • Generate the ransom note containing the instructions in obtaining the decryption tool.
  • Virus remains active on the computer to encrypt newer files.
Technical Details
Virus Name:Ransom:Win32/StopCrypt.AK!MTB
Threat Type:STOP/DJVU Ransomware, Crypto-Virus
Similar Detections:Alibaba : Ransom:Win32/StopCrypt.6e81788d
Avast : Win32:DropperX-gen
Avira : TR/AD.VidarStealer.fjimx
BitDefender : Trojan.GenericKD.43929738
ClamAV : Win.Trojan.Tofsee-9770082-1
DrWeb : Trojan.Siggen10.32818
F-Secure : Trojan.TR/AD.VidarStealer.fjimx
Fortinet : W32/Kryptik.HGNJ!tr
Ikarus : Trojan.Win32.Crypt
Kaspersky : HEUR:Trojan.Win32.Chapak.gen
Malwarebytes : Trojan.MalPack.GS
McAfee : Trojan-FSUC!6463FA6A18BF
NANO-Antivirus : Trojan.Win32.Chapak.hxpnhf
Panda : Trj/GdSda.A
Rising : Ransom.StopCrypt!8.11C05 (TFE:5:xfgOqVjWH2N)
Sophos AV : Mal/Generic-S
Symantec : ML.Attribute.HighConfidence
TrendMicro : Trojan.Win32.WACATAC.THICOBO
Webroot : W32.InfoStealer.Zeus

How to remove Ransom:Win32/StopCrypt.AK!MTB?

To totally remove Ransom:Win32/StopCrypt.AK!MTB from the computer and get rid of relevant virus and trojan, please execute the procedures as stated on this page. Make sure that you have completely scan the system with suggested malware removal tools and virus scanners.

Quick Fix - Scan the PC with Combo Cleaner for Windows

Combo Cleaner is a trusted PC security and optimization tool equipped with powerful virus and malware detection engine. This program can get rid of hazardous virus like Ransom:Win32/StopCrypt.AK!MTB through this procedure.

1. Download the application from the following page:

2. Save the file to your preferred location.

3. Double-click the downloaded file CCSetup.exe and install with the default settings.

CC for Windows Installation

4. At the end of the setup process, click Finish to run Combo Cleaner.

5. The tool will update the signature file, please wait for this process to complete.

6. To begin checking for threats like Ransom:Win32/StopCrypt.AK!MTB, click on the Start Scan button. Wait for this scan to finish.

CC for Windows Start Scan

7. At the end of the scan process, click on Remove all threats to delete Ransom:Win32/StopCrypt.AK!MTB virus including all malicious objects from the computer.

Free features of Combo Cleaner for Windows include Disk Cleaner, Big Files finder, Duplicate files finder, and Uninstaller. To use antivirus, privacy scanner, and to delete identified threats, users have to upgrade to a premium version.

Please continue with the succeeding removal procedures if your are comfortable to manually get rid of the virus and malicious items linked with it.

Stage 1 : Start Windows in Safe Mode With Networking

Windows 10 Guide

1. Click on Windows logo and select Power icon when options pop-ups.
2. Select Restart from the options while pressing Shift key on the keyboard.
3. Choose an Option window will appear, select the Troubleshoot button.
4. On next window, please choose Advanced Option.
5. On Advanced Option window, click on Startup Settings and then, click Restart button to reboot the computer.
6. When Windows boot on Startup Settings, press function key F5 or number 5 on keyboard.

A simpler alternative for Windows 10 users is to scan the computer with Microsoft Defender Offline. This will run a virus scan in the recovery environment.

Windows 8 Guide

1. Click Windows Start icon at the lower left section of the screen.
2. Open Search window and type Advanced in the field. It will open General PC Settings.
3. Click on Advanced Startup and then, click on Restart Now button.
4. Once the computer starts in Advanced Startup option menu, select Troubleshoot.
5. Next, click on Advanced Options to reveal the next section.
6. Click Startup settings and then, click Restart button to boot the PC in Startup Settings.
7. Use function key F5 or number key 5 to Enable Safe Mode with Networking.

Stage 2 : Run a virus scanner

To remove Ransom:Win32/StopCrypt.AK!MTB, we suggest that you scan the infected computer with this powerful virus removal tool. It can detect and get rid of Trojans, viruses, malware, and adware from the infected computer. To fully protect the computer against Ransom:Win32/StopCrypt.AK!MTB or similar attack, you can activate Sophos to have real-time scanning and complete defense against all forms of threats.

1. Download Sophos Virus Removal Tool from the link below. Save the file on your computer where you can easily access it.

2. Once the download completes, browse the location of the file. Double-click to run the program and begin the install process.

3. On first windows of installation wizard, click Next to continue. Then, it will display the program’s License Agreement. You need to Accept the terms in order to proceed. If Windows prompts for User Account Control, please click Yes to proceed.

4. On succeeding windows, click Next or Continue to carry on with the installation. After completing the installation process, Launch Sophos Virus Removal Tool.

5. Internet connection is required when running this scanner in order to download important updates. Make sure that everything is up-to-date to effectively remove virus like Ransom:Win32/StopCrypt.AK!MTB.

6. Click the  button to  carry out the Scan. This will check the system for presence of malicious objects, malware, and viruses. The tool reveals items that were found linked to Ransom:Win32/StopCrypt.AK!MTB and other suspicious entities. Be sure to remove all identified threats.

Screenshot of Sophos Virus Scan

After executing the above instructions, Ransom:Win32/StopCrypt.AK!MTB should have been eliminated totally from the computer. If there are still signs of infection or computer is displaying unusual behaviors, please continue with the remaining procedures.

Stage 2 :Double Check with Microsoft Security Apps

Microsoft Windows has built-in security application that you can use to double-check if computer is still infected with Ransom:Win32/StopCrypt.AK!MTB. For Windows 8 and 10 users, please run Windows Defender. Users of Windows Vista and older versions can utilize Microsoft Security Essentials to remove Ransom:Win32/StopCrypt.AK!MTB virus.

Windows 8 / 10 Instructions:

Windows Defender is a free tool that was built help you remove Ransom:Win32/StopCrypt.AK!MTB, viruses, and other malicious items from Windows 8 or Windows 10 system. Follow these procedures to scan your computer with Windows Defender:

1. Tap or click the Search charm, search for defender, and then open Windows Defender.

If Windows Defender is not yet installed on the computer, please proceed to download page using the link below. It also contains detailed instruction to install and use the program effectively. Proper usage is required to totally remove Ransom:Win32/StopCrypt.AK!MTB


2. On the Home tab, click Full under Scan Options. Click Scan now to start scanning for presence of Ransom:Win32/StopCrypt.AK!MTB. The process may take a while to complete.


3. After the scan, delete/quarantine identified threats wether it is relevant to Ransom:Win32/StopCrypt.AK!MTB or not. You may now restart Windows to complete the virus removal process.

Windows XP, Windows Vista, and Windows 7 Instructions:

1. Open Microsoft Security Essentials by going to Windows Start > All Programs. If the tool is not yet installed on the computer, please download Microsoft Security Essentials from the link below. Save the file on your hard drive.

Complete installation guide and usage are also provided on the same link. It is essential in removing Ransom:Win32/StopCrypt.AK!MTB effectively. If Microsoft Security Essentials is already installed on the PC, please proceed with the steps below.

2. On Microsoft Security Essentials Home screen, please choose Full under Scan Options.

MSE Full Scan

3. Click on Scan Now button to start detecting Ransom:Win32/StopCrypt.AK!MTB items, viruses, and malware on the PC. Scan may take a while, please be patient and wait for the process to end.

How to protect the computer from Ransom:Win32/StopCrypt.AK!MTB?

The initial defense that comes to the mind of any computer users is to install an anti-virus or anti-malware program. This move is sensible and probably the most practical way to protect the computer against Ransom:Win32/StopCrypt.AK!MTB attack. Hence, keep in mind that having a security software do not give full guarantee of protection. The most part of the prevention still lies on being cautious of users and therefore we are providing the following information as guidelines to protect the computer from virus infection.

Avoid Malicious Websites

There are enormous numbers of websites that was made for the primary purpose of spreading Ransom:Win32/StopCrypt.AK!MTB. Normally, these sites are involved in integrating malicious pop-up and browser hijacker, that will eventually cause further virus infection. Avoid such kind of websites.

Delete Phishing Emails

The mass-mailing of computer viruses gives the attackers the luxury of spreading their malicious code in just one send off. This will arrive in the inbox as email that appears to be from a legitimate organization. So, if you receive an unexpected email with a link or an attached file, better delete it immediately.

Do Not Click a Suspicious Link

Links from social media, forums, and blog sites are sometimes being utilized by attackers to drive web users to a malicious page that contains malicious code. Therefore, do not just click on any link especially if it looks suspicious. Accidental access to the destination site may lead to Ransom:Win32/StopCrypt.AK!MTB infection.

Be Careful When Downloading Files

Cracked software, serial key generators, and several freeware are seen as another method that spreads the Ransom:Win32/StopCrypt.AK!MTB virus. Avoid acquiring these types of application and if there is a need to download a freeware or shareware, be sure to obtain it from the official website or trusted providers.

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