How to decrypt files encrypted by a virus

This write-up is intended to assist the users whose files have been encrypted by a ransomware virus in decrypting their personal files without paying a ransom.

Cybercriminals have become proficient in weaponizing benign technologies over time. For instance, it used to be hard to imagine malicious use cases involving cryptography – a field of science meant to secure sensitive communications even if it got intercepted by a third-party. Its exploitation has been going on for years, though. Back in 2013, black hats came up with a scheme where their perpetrating code could apply a cipher to lock down the victims’ valuable data and hold it for ransom. The infection called CryptoLocker is believed to be the progenitor of all mainstream file-encrypting ransomware. These blackmail attacks have considerably evolved ever since, now featuring diversified distribution channels, automated handling of encryption keys, antivirus evasion, sophisticated payment processing, and victim interaction modules some legit software vendors will envy.

A commonplace fully-fledged ransomware strain can reach target computers in a variety of ways. Malspam (malicious spam) is by far the most widespread vector. Its essence boils down to mass email campaigns that deliver trojanized attachments to thousands of users in one hit. The embedded files can be anything from Microsoft Office documents with harmful macros on board, to archives concealing malign JavaScript objects under layers of regular-looking extraction routine. The success rate of ransomware installs via this technique is fairly high due to the fact that these attachments are disguised as something eye-catching, such as an invoice, package delivery notice, job offer, resume, and the like.

One more method of depositing a file-encrypting virus onto a Windows PC is through compromised remote desktop services. This attack chain engages an instance of brute-forcing RDP credentials and then executing the dangerous binary manually. Some ransomware species are making the rounds by means of exploit kits, that is, offending entities that find and use a system’s software vulnerabilities once the user visits a hacked website with stealthy bad scripts on it. The latter mechanism appears to be gradually fading away in 2018, which may be caused by a high cost of renting turnkey exploit kits on the dark web.

No matter how exactly a ransom virus has infiltrated a computer, the subsequent logic of its activity is quite uniform. It tries to invoke a command that deletes all shadow copies of the victim’s files, although sometimes this attempt may fail, which is a favorable scenario for the plagued user. Next, the infection scans all HDD volumes, removable drives and network shares for items with specific extensions that correspond to the most popular types of data. This way, it spots all the documents, photos, videos, databases, and many other file formats that are most likely to matter to the user. Then, cryptography enters the game as the culprit encrypts all the objects found during the scan. It may leverage a symmetric cryptosystem, such as AES (Advanced Encryption Standard), or an asymmetric cipher, such as RSA, or both. As part of the data skewing activity, most of these pests will append a new extension to every encrypted file, while some may also completely scramble filenames.

Since the crooks are the ones who own the decryption key, these files may end up irrecoverable unless the victim follows the attackers’ recommendations. It all comes down to ransom, which is typically payable in Bitcoin or other cryptocurrencies, including Dash and Monero. The malefactors’ instructions are explicated in a ransom note, which is a TXT, HTML or HTA file that’s dropped on the contaminated computer’s desktop and inside folders with hostage data. Most of the time, the user is coerced to visit a specific page via Tor browser and follow the payment steps on it. Sometimes there is an option to decrypt a couple of files for free as a proof that the recovery does work. A deadline for submitting the ransom is one more standard attribute of the incursion – if you don’t pay on time, the amount will double.

Unfortunately, the majority of today’s dominating ransomware lineages cannot be decrypted for free, because the architects of these campaigns utilize cryptography competently enough. Meanwhile, there are quite a few specimens with encryption flaws, which has allowed researchers to create automatic decryptors. So, before you make a decision on how to sort things out if you’ve been hit by a file-encrypting virus, go to this one-stop recovery tutorial that encompasses a catalogue of all known free ransomware decryption tools and other useful resources. It will help you identify the sample you’ve come across and check whether it can be cracked without sending a ransom to the criminals. Otherwise, follow the tips below to try and restore your important data using the power of forensics.

Crypto ransomware automated removal and data recovery

When faced with ransomware like Crypto, one of the best shortcuts in terms of removal is to use Combo Cleaner, a lightweight and incredibly effective application with PC security and optimization features under the hood. It detects and thoroughly deletes threats while giving you insights into the overall health of your computer.

This program’s protection power spans modules that forestall all known types of malware, including ransomware and browser hijackers, and take your online security to the next level by blocking phishing sites and other suspicious web pages. Follow these simple steps to eliminate the infection for good:

1. Download Combo Cleaner installer.

Download Crypto remover

^{Combo Cleaner scans your PC with no strings attached, but you’ll have to buy its fully functional version to remove the threats it detects. The disk optimization tools that find large files and duplicates are free to use.}

2. Open the CCSetup.exe file to get started. Several subsequent screens will allow you to make initial customizations so that the program works exactly as you need from the get-go.

3. The installation will be followed by an update of malware signatures. Once this process is through, click the Start Scan button in the left-hand sidebar.

4. Combo Cleaner will then check system locations that are most often polluted by Windows malware. The first scan can take a while to finish.

5. Combo Cleaner will display a system tray notification as soon as the scan is over. Click the Resolve found threats button to view the results.

6. The scan summary shows the names and types of the detected threats as well as their statuses and locations. Click the Remove all threats button and follow further on-screen prompts to get rid of these items.

Data recovery toolkit to the rescue

Some strains of ransomware are known to delete the original files after the encryption routine has been completed. As hostile as this activity appears, it can play into your hands. There are applications designed to revive the information that was obliterated because of malfunctioning hardware or due to accidental removal. The tool called Stellar Data Recovery features this type of a capability and therefore it can be applied in ransom attack scenarios to at least get the most important files back. So use the app to get an idea of what data can be restored and let it do the recovery job. Here is a step-by-step walkthrough:

1. Download and install Stellar Data Recovery.

Download Stellar Data Recovery

2. Open the application, select the types of recoverable files to look for, and click Next.

3. Choose the areas you want the tool to recover from and click the Scan button.

4. Having scanned the specified locations, the program will display a notification about the total amount of recoverable data. Close the dialog and click the Recover button. This will hopefully help you get some of your valuable files back.

Crypto ransomware manual removal and file recovery

Some ransomware strains terminate themselves after completing the encryption job on a computer, but some don’t. Furthermore, the Crypto virus may prevent victims from using popular antimalware tools in order to stay on board for as long as possible. Under the circumstances, it may be necessary to utilize the Safe Mode with Networking or System Restore functionality.

Be advised that even after the ransomware is removed, files will still be encrypted and inaccessible. The malicious code cleanup part, however, is important because it keeps a relapse of the infection from occurring further on and eliminates all opportunistic malware.

Decrypt files encrypted by a virus

Cracking the crypto used by this ransom Trojan is more of a science fiction thing rather than an attainable prospect for the masses. This is why the troubleshooting in predicaments of this sort is a matter of two approaches: one is to pay the ransom, which isn’t an option for many victims; and the other is to apply instruments that take advantage of the ransomware’s possible weaknesses. If the latter is your pick, the advice below is a must-try.

Ransomware Prevention Tips

To avoid Crypto ransomware and other file-encrypting infections in the future, follow several simple recommendations:

These techniques are certainly not a cure-all, but they will add an extra layer of ransomware protection to your security setup.

Revise your security status

Post-factum assessment of the accuracy component in malware removal scenarios is a great habit that prevents the comeback of harmful code or replication of its unattended fractions. Make sure you are good to go by running an additional safety checkup. Another benefit of using the antimalware tool is that it will keep ransomware threats from intruding on your computer further on.

Download Crypto removal tool