How to decrypt .ykcol virus files – Ykcol/Locky ransomware

A fresh update of the Locky ransomware has brought about several changes, including the .ykcol extension being affixed to files, and ykcol.htm/ykcol.bmp rescue notes.

Locky, one of the heavyweights on the online extortion arena, has undergone another major tweak. Its latest edition is referred to as Ykcol based on the new file extension token and the names of data decryption how-to manuals added to a contaminated system. Meanwhile, this variant shares most of its properties with the predecessor dubbed Lukitus. In particular, it is being distributed via malicious spam carrying a trojanized file on board. These emails may be camouflaged as invoice notifications and are typically titled “Status of invoice”. Note that this is merely one of the spam waves reportedly involved in Locky distribution at this point, so other phishing themes are most likely to surface as well. Regardless of the subject, the attached ZIP archive has a malicious VBS file inside. When opened, this entity automatically downloads the Ykcol binary onto the target computer behind the scenes.

As soon as the payload has been executed, it traverses the host for potentially important data. To this end, it scans hard drive partitions, removable repositories such as USB memory sticks, and network drives in search of files with specific extensions matching popular formats. Every spotted item is subject to rock-solid encryption. The Ykcol/Locky ransomware leverages a combination of two ciphers, RSA-2048 and AES-128, to render victims’ valuable data inaccessible. The aftermath of this skewing routine is a severe modification of filenames. They turn into long strings consisting of 36 hexadecimal characters followed by the above-mentioned .ykcol string. For instance, a file originally named Cat.jpg will morph into something like this: IZ7FDG12-KQ76-ITX5-AF3819CF-55DCDC930421.ykcol.

To let the victim know what’s going on and how to act, the Ykcol virus creates recovery how-to manuals named ykcol.htm and ykcol.bmp. These may assume an alternate shape like ykcol-[4 chars].htm/bmp. The former is dropped on the desktop and sprinkled across folders with hostage data. The latter edition (BMP file) is used to replaces the user-defined desktop background with some warning text conveying basic restoration steps. Both say the following, “!!! IMPORTANT INFORMATION !!!! All of your files are encrypted with RSA-2048 and AES-128 ciphers.” Then goes a part reading, “Decrypting of your files is only possible with the private key and decrypt program, which is on our secret server.”

Ultimately, the victim is pressured into visiting a specially crafted Tor resource titled the Locky Decryptor Page. This page, incidentally, has been invariable throughout Locky’s existence, with the only volatile part being the size of the ransom. In the case of the Ykcol ransomware, the amount is 0.25 Bitcoin. The page provides the Bitcoin wallet address to submit the ransom, and contains a field for the decryptor download link which will supposedly become available once the payment has been verified. A huge caveat in fighting all iterations of Locky is that the crypto is too strong to brute force or otherwise get around. So backups pose the best response to such attacks. If there are none, it’s worthwhile trying a few forensic techniques listed below.

Ykcol ransomware automated removal and data recovery

When faced with ransomware like Ykcol, 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 Ykcol 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.

Ykcol 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 Ykcol 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.

Ways of non-ransom recovery of .ykcol extension files

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 Ykcol 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 Ykcol removal tool