Nesa is a DJVU family of ransomware-type infections. The ransomware encrypts your private files (video, photos, documents). The crypted files can be tracked by specific “.nesa” extension. So, you can’t use them at all.
In this tutorial I will try to help you remove Nesa virus without any payment. As bonus I will assist you in decoding your crypted files.
What is “Nesa”?
Nesa can be correctly identify as a ransomware infection.
Ransomware is a specific kind of virus that crypted your documents and then forces you to pay to restore them. Note that DJVU (aka STOP) ransomware family was first revealed and discovered by virus analyst Michael Gillespie1.
Nesa is basically similar to other representatives of the same family: Karl, Domm, Domn. It crypted all popular file types. Hence, you cannot work with the your documents . Nesa adds its particular “.nesa” extension into all files. For example, the file “video.avi”, will be amended into “video.avi.nesa”. As soon as the encryption is accomplished, Nesa generates a special file “_readme.txt” and puts it into all folders that contain the modified files.
This text asking payment is for get files back via decryption key:
The cryptography algorithm used by Nesa is AES-556. So, if your files got encrypted with a specific decryption key, which is totally unique and there are no other copies. The sad reality is that it is impossible to recover the information without the unique key available.
In case if Nesa worked in online mode, it is impossible for you to gain access to the AES-556 key. It is stored on a distant server owned by the criminals who distibute the Nesa ransomware.
For receiving decryption key the payment should be $980. To obtain the payment details the victims are encouraged by the message to contact the frauds by email (firstname.lastname@example.org), or via Telegram.
Do not pay for Nesa!
Please, try to use the available backups, or STOPDecrypter tool
_readme.txt file also indicates that the computer owners must get in touch with the Nesa representatives during 72 hours starting from the moment of files where crypted. On the condition of getting in touch within 72 hours users will be granted a 50% rebate, thus the ransom amount will be minimized down to $490). Yet, stay away from paying the ransom!
I certainly recommend that you do not contact these crooks and do not pay. The one of the most real working solution to recover the lost data – just using the available backups, or use STOPDecrypter tool.
The peculiarity of all such viruses apply a similar set of actions for generating the unique decryption key to recover the ciphered data.
Thus, unless the ransomware is still under the stage of development or possesses with some hard-to-track flaws, manually recovering the ciphered data is a thing you can’t really perform. The only solution to prevent the loss of your valuable data is to regularly make backups of your crucial files.
Note that even if you do maintain such backups regularly, they ought to be put into a specific location without loitering, not being connected to your main workstation.
For instance, the backup may be kept on the USB flash drive or some alternative external hard drive storage. Optionally, you may refer to the help of online (cloud) information storage.
Needless to mention, when you maintain your backup data on your common device, it may be similarly ciphered as well as other data.
For this reason, locating the backup on your main PC is surely not a good idea.
How I was infected?
Nesa has a various methods to built into your system. But it doesn’t really matter what method was used in your case.
Nesa ransomware attack following a successful phishing attempt.
Nevertheless, these are the common leaks through which it may be injected into your PC:
- hidden installation along with other apps, especially the utilities that work as freeware or shareware;
- dubious link in spam emails leading to the Nesa installer
- online free hosting resources;
- using illegal peer-to-peer (P2P) resources for downloading pirated software.
There were cases when the Nesa virus was disguised as some legitimate tool, for example, in the messages demanding to initiate some unwanted software or browser updates. This is typically the way how some online frauds aim to force you into installing the Nesa ransomware manually, by actually making you directly participate in this process.
Surely, the bogus update alert will not indicate that you are going to actually inject the Nesa ransomware. This installation will be concealed under some alert mentioning that allegedly you should update Adobe Flash Player or some other dubious program whatsoever.
Of course, the cracked apps represent the damage too. Using P2P is both illegal and may result in the injection of serious malware, including the Nesa ransomware.
To sum up, what can you do to avoid the injection of the Nesa ransomware into your device? Even though there is no 100% guarantee to prevent your PC from getting damaged, there are certain tips I want to give you to prevent the Nesa penetration. You must be cautious while installing free software today.
Make sure you always read what the installers offer in addition to the main free program. Stay away from opening dubious email attachments. Do not open files from the unknown addressees. Of course, your current security program must be always updated.
The malware does not speak openly about itself. It will not be mentioned in the list of your available programs. However, it will be masked under some malicious process running regularly in the background, starting from the moment when you launch your PC.
The message by the Nesa ransomware states the following frustrating information:
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-2P5WrE5b9f 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: email@example.com Reserve e-mail address to contact us: firstname.lastname@example.org Our Telegram account: @datarestore Mark Data Restore Your personal ID: XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
The image below gives a clear vision of how the files with “.nesa” extension look like:
How to remove Nesa virus?
In addition to encode a victim’s files, the Nesa infection has also started to install the Azorult Spyware on system to steal account credentials, cryptocurrency wallets, desktop files, and more.
Reasons why I would recommend GridinSoft2
There is no better way to recognize, remove and prevent ransomware than to use an anti-malware software from GridinSoft3.
Download Removal Tool.
You can download GridinSoft Anti-Malware by clicking the button below:
Run the setup file.
When setup file has finished downloading, double-click on the install-antimalware-fix.exe file to install GridinSoft Anti-Malware on your system.
An User Account Control asking you about to allow GridinSoft Anti-Malware to make changes to your device. So, you should click “Yes” to continue with the installation.
Press “Install” button.
Once installed, Anti-Malware will automatically run.
Wait for the Anti-Malware scan to complete.
GridinSoft Anti-Malware will automatically start scanning your PC for Nesa infections and other malicious programs. This process can take a 20-30 minutes, so I suggest you periodically check on the status of the scan process.
Click on “Clean Now”.
When the scan has finished, you will see the list of infections that GridinSoft Anti-Malware has detected. To remove them click on the “Clean Now” button in right corner.
How to decrypt .nesa files?
It work when the Nesa infection used an offline key for encryption.
You can download free decryption tool here: STOPDecrypter. This tool includes a BruteForcer only for variants which use XOR encryption, a simple symmetric cipher that is relatively easy to break. The decrypter tool requires victims to provide an encrypted and original file pair greater than 150KB.
Download STOPDecrypter tool:
Extract STOPDecrypter tool to your Desktop folder:
Run STOPDecrypter tool:
Remember: STOPDecrypter should be run as an Administrator from the Desktop.
Select your folder and press “Decrypt” button:
What the next?
If the guide doesn’t help you to remove Nesa infection, please download the GridinSoft Anti-Malware that I recommended. Also, you can always ask me in the comments for getting help. Good luck!
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