How to remove Sigma virus and restore encrypted files

Sigma ransomware virus

Sigma ransomware already infected many machines around the world via easiest manner: fraud e-mails with viral attachments. Virus adds README.html file on the desktop, where victim can find how-to-pay instruction. In addition, virus changes desktop background to the picture with info message. Ransomware requires 1000$ for data restoration and double this sum after seven days. Fraudsters use exploits to penetrate the computer, but well-known program vendors promptly fix them. After the infection, ransomware scans the hard drive to find the files for encryption and their approximate worth. Nowadays, any modern ransomware is able to cypher text, video, audio and image files in all popular formats. Sigma cyphers all folders, but the ones that might be business documents go first. All software in the system will be unaffected since scammers want only information. Encryption is made with the help of well-known encryption algorithms, and it is so complex that that it cannot be bruteforced. This is the basis for unbelievable success of this type of viruses in recent years: common customer, even if he has a fairly good knowledge of the PC, won't ever recover the files, and will have no choice except paying to scammers. The sole manner to restore the information is to crack the fraudster's website and obtain the encryption keys. Some experienced hackers can retrieve encryption keys through defects in viruse's program code.

That item is about Sigma virus that infects machines around the world, and cyphers their files. In this page you can find complete info on what is Sigma, and the removal of Sigma from your machine. Besides, we'll tell you how to restore the cyphered files and is it possible.

Sigma ransomware virus

For all types of computer viruses, one thing is true: it's much easier to dodge it than to get rid of its fruits. Statistically, 90% of users see the significance of computer knowledge just after ransomware infection. It's very easy to reduce the chances to get ransomware if you'll follow these rules:

    • Do not ignore the red flags that your laptop shows. Information encrypting is a complicated operation that consumes a considerable amount of system resources. If you mention a noticeable drop in workstation power or detect a unknown process in the Process Manager, you should switch off the laptop, start it in safe mode, and run the AV-tool. These measures, if the laptop is really infected, will protect some of your data.
    • Be careful with the messages which contain files. The #1 template of fraud messages is the notification about prize gaining or parcel obtaining. You also should be attentive with business-related messages, particularly if the sender's address and the content is unknown. lawsuits, Bills for products and services, summaries, claims and similar sensitive files do not be sent without warning, and the receiver should know the sender. Otherwise, it is a scam.
    • Don't admit any alterations to the system, originating from strange software. One of the simplest methods of data restoration is the restoration via Shadow Copies, and hackers have added the deletion of those copies in the primary functionality of ransomware. The deleting of copies requires admin rights and verification from the user. So, if you do not confirm changes from a strange software at the proper moment, you will save the chances to decrypt all lost information for free.

You should understand that deleting Sigma is only the first and obligatory turn for the safe work of the system. To get back the data you should familiarize with the tips in the following section of our article. In case of ransomware we do not give the manual deletion guide, because its complication and the probability of failing is extremely high for regular user. We don't advise anyone to eliminate ransomware manually, because it has numerous protection mechanics that will interfere you. The most common viral protection technique is the removal of data in case of file decryption or ransomware removal attempt. To avoid this, follow the advices below.

Removal instruction

Step 1. Boot into Safe mode

Safe mode

Start -> Msconfig.exe

Safe mode. Step 1

On the tab Boot select Safe boot

Safe mode. Step 2

Step 2. Check Startup folder

Start -> Msconfig.exe ->Disable unknown programs in the Startup tab


Step 3. Check hosts file

Modify hosts file, that located in C:\Windows\System32\drivers\etc\ .

Hosts file.Step 1

Open the file with Notepad and delete suspicious strings.

Hosts file.Step 2

It has to look like this:

Hosts file.Step 3

Step 4. Scan the system with antiviral scanner


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Step 5. Disable Safe mode

Start -> Msconfig.exe ->Disable Safe boot in the Boot tab

Deactivate Safe mode

If you performed all actions, described in above paragraph - it's time to restore the data. We won't try to reverse the encryption, but we'll recover them using OS features and the additional programs. Usually, to get back the data, the victim has to ask for assistance on specialized forums or from famous malware researchers and antiviral software manufacturers. If you can't linger and are going to restore the data manually - here's the complete article on that topic: article about files decryption.



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