How to Remove Nosu Ransomware Virus (.nosu Files)

An infection with the dangerous Nosu ransomware virus leads to serious security issues. With our removal guide victims can try to restore and protect their computers.

The Nosu ransomware is a new malware threat that aims to process certain user files with a strong cipher in order to render them inaccessible. The associated extension will be applied to the victim data and a ransomware note will be crafted in order to blackmail the users into paying the victims a ransomware decryption fee.

When the infection has been triggered the Nosu ransomware will begin the malicious sequence. It can run different services and components depending on the built-in instructions by the hackers. In most cases, this will harvest information that can reveal information about the victims and infected computers. This data is collected and sent to the hacker operators. If instructed so this can be done via a Trojan connection that will establish a secure connection to the operators making it possible for them to take over control of the Nosu ransomware infected hosts.

Other behavior can be included in the main engine such as the Windows Registry manipulations. It can create entries for itself and modify existing ones in order to cause performance issues, data loss and unexpected errors. As soon as all modules have completed running the ransomware engine will be called. It will start to process sensitive user data with the .nosu extension. A lock-screen instance will be started in order to blackmail the users into paying the hackers a decryption fee. Lockscreen instances in some cases can block the ordinary interaction with the computer until the threat is completely removed.

Manual Removal Guide
Files Recovery Approaches
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Note for Mac users!
In case that your Mac has been affected by Nosu or you suspect that other threats are running on it you can follow detailed instructions on how to detect and remove Mac viruses so you can keep the device clean and secure.

Distribution of Nosu Ransomware Virus

Nosu virus is a new data locker ransomware that has been released in active attack campaigns against computer users worldwide. The threat could be utilizing common tactics of distribution to infect computer systems.

One of the easiest ways for the criminals to spread the payload of Nosu ransomware is by attaching it to email messages that are later released in active attack campaigns. The method allows hackers to send the virus to large lists of potential victims. The attachments to malicious email spam messages usually have Word documents or other types of files which users open without hesitation. Once opened on a target host these compromised files trigger the ransomware payload and infect the device with Nosu crypto virus. Another infection tactic related to emails is hyperlink inserted in the content of the messages. The links are usually labeled as leading to a familiar website or a file of user interest.

Computer criminals behind this new ransomware can be using malicious sites or download portals to distribute malware of different kinds, including Nosu virus. A popular option is the use of infected documents which may be of different types ‒ spreadsheets, rich text documents, presentations and databases. They are modified to initiate the virus once the built-in scripts are run. Usually when the files are opened a notification will ask the users to run the macros (scripts). If this is done the infection follows.

The hacker-controlled sites are specialist portals that have been created either manually or automatically by the criminals behind Nosu virus. They can either directly distribute the threat by initiating various scripts or automated operations or link to such instances. Redirects are usually caused by email interaction, ad networks or other browsing activity. However one of the main sources is the availability of browser hijackers. They are malicious add-ons made for the most popular web browsers ‒ Mozilla Firefox, Google Chrome, Internet Explorer, Opera, Microsoft Edge and Safari. Once installed they not only infect the users with the malware but also redirect the victims to a hacker-controlled site. Depending on the configuration the browser hijackers can also steal sensitive information such as any stored passwords, account credentials, history, bookmarks, form data and settings.

Impact of Nosu Ransomware Virus

The Nosu is a new ransomware sample that has just been announced in a security report. It is based on the code of the infamous STOP ransomware and distributed by an unknown hacker collective or an individual malicious actor.

The ransomware samples may begin the infection process by calling a data collection command. It has the ability to harvest data into that can be grouped into two categories:

  • Anonymous Data — The engine can collect various information that in the end is used to create a unique machine ID. This value is used to differentiate infected computers from each other. The ID is made up of values associated with the installed hardware components, certain user settings and operating system variables. Using a special algorithm part of all of these data is computed and the resulting ID is made.
  • Private Data — Information that can reveal the identity of the users is also collected by the engine. This may include strings such as their full name and personal details like their interests, phone numbers, email accounts and even stored passwords for online services. There is a serious risk of abuse as such pieces of information can be used to perform identity theft and financial abuse.

This information can then be used by the next module that is run during the behavior pattern — security bypass. It will scan the system for any running security software that can interfere with the virus payload. Common forms include anti-virus programs, virtual machine hosts and debug environments. When they are disabled the main ransomware engine will be able to infect all parts of the operating system.

Usually the Windows Registry changes will follow next. The engine can modify values belonging to the operating system and third-party applications. Depending on the type of Registry entries the resulting effects may be different — from troubles starting certain functions to serious performance issues.

The Nosu virus can also be instructed into creating registry values for itself. This is done in combination with other modifications and is related to the persistent installation of the ransomware. The engine will be started automatically when the computer is powered on. An additional effect of this change is that the victims may not be able to able to boot into the recovery boot menu.

To prevent effective recovery the engine can be programmed to delete important system data. Contents include Shadow Volume Copies and System Restore Points are deleted in order to make recovery much more difficult.

Some infections can also install a separate Trojan module. In most cases, this will set up an encrypted connection to a hacker-controlled server which will be maintained during the infection’s duration. It would allow the operators to spy on the victim users in real-time, steal their files and also deliver additional viruses.

When all of the devised steps have been executed the actual encryption process will be started. The Nosu like all previous versions will follow the typical infection pattern. This model will target specific user data according to a built-in list of target file type extensions that will be processed by a strong cipher. A typical list will feature the following file type extensions:

  • Backups
  • Databases
  • Archives
  • Videos
  • Music
  • Images

The resulting files will be renamed with the .nosu extension. A ransom note will be dropped to extort a ransom fee for the infected files.

Remove Nosu Ransomware Virus and Restore PC

Please note that paying the requested ransom fee to cyber criminals does not really solve your problem with Nosu crypto virus. In fact, you only encourage hackers to continue spreading ransomware of this kind. Instead, you must remove the threat immediately, and only then look for optional ways to recover your data.

WARNING! Manual removal of Nosu ransomware virus requires being familiar with system files and registries. Removing important data accidentally can lead to permanent system damage. If you don’t feel comfortable with manual instructions, download a powerful anti-malware tool that will scan your system for malware and clean it safely for you.

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Nosu Ransomware Virus – Manual Removal Steps

Start the PC in Safe Mode with Network

This will isolate all files and objects created by the ransomware so they will be removed efficiently. The steps below are applicable to all Windows versions.

1. Hit the WIN Key + R

2. A Run window will appear. In it, write msconfig and then press Enter

3. A Configuration box shall appear. In it Choose the tab named Boot

4. Mark Safe Boot option and then go to Network under it to tick it too

5. Apply -> OK

Show Hidden Files

Some ransomware threats are designed to hide their malicious files in the Windows so all files stored on the system should be visible.

1. Open My Computer/This PC

2. Windows 7

    – Click on Organize button
    – Select Folder and search options
    – Select the View tab
    – Go under Hidden files and folders and mark Show hidden files and folders option

3. Windows 8/ 10

    – Open View tab
    – Mark Hidden items option

how to make hidden files visible in Windows 8 10 bestsecuritysearch instructions

4. Click Apply and then OK button

Enter Windows Task Manager and Stop Malicious Processes

1. Hit the following key combination: CTRL+SHIFT+ESC

2. Get over to Processes

3. When you find suspicious process right click on it and select Open File Location

4. Go back to Task Manager and end the malicious process. Right click on it again and choose End Process

5. Next, you should go folder where the malicious file is located and delete it

Repair Windows Registry

1. Again type simultaneously the WIN Key + R key combination

2. In the box, write regedit and hit Enter

3. Type the CTRL+ F and then write the malicious name in the search type field to locate the malicious executable

4. In case you have discovered registry keys and values related to the name, you should delete them, but be careful not to delete legitimate keys

Click for more information about Windows Registry and further repair help

Recover Encrypted Files

WARNING! All files and objects associated with Nosu ransomware virus should be removed from the infected PC before any data recovery attempts. Otherwise the virus may encrypt restored files. Furthermore, a backup of all encrypted files stored on external media is highly recommendable.

DOWNLOAD SpyHunter Anti-Malware Tool

 
SpyHunter is a Windows application designed to scan for, identify, remove and block malware, potentially unwanted programs (PUPs) and other objects. By purchasing the full version, you will be able to remove detected malware instantly. Additional information about SpyHunter / Help to uninstall SpyHunter

1. Use present backups

2. Use professional data recovery software

Stellar Phoenix Data Recovery – a specialist tool that can restore partitions, data, documents, photos, and 300 more file types lost during various types of incidents and corruption.

3. Using System Restore Point

    – Hit WIN Key
    – Select “Open System Restore” and follow the steps

restore-files-using-windows-system-restore-point

4. Restore your personal files using File History

    – Hit WIN Key
    – Type restore your files in the search box
    – Select Restore your files with File History
    – Choose a folder or type the name of the file in the search bar
    – Hit the “Restore” button

Preventive Security Measures

  • Enable and properly configure your Firewall.
  • Install and maintain reliable anti-malware software.
  • Secure your web browser.
  • Check regularly for available software updates and apply them.
  • Disable macros in Office documents.
  • Use strong passwords.
  • Don’t open attachments or click on links unless you’re certain they’re safe.
  • Backup regularly your data.
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    Author : Gergana Ivanova

    Gergana Ivanova is a computer security enthusiast who enjoys presenting the latest issues related to cyber security. By doing thorough researches and sharing them on BestSecuritySearch, she hopes that more victims of malware infections will be able to secure their corrupted computer systems properly and eventually recover lost files.


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