Arena virus: how to recover .arena extension files (Dec. 2017)

New persona of the Crysis ransomware has been released that appends the .arena extension to encrypted data and still implements encryption securely.

The crypto ransomware breed known as Crysis, or Dharma, appears to be gearing up for a rise. It has been spawning malicious descendants almost on a weekly basis since early August 2017, having been in an idle state for months on end. The latest offshoot has introduced the .arena file extension token to the digital extortion environment. After encrypting a victim’s personal data, this Crysis mod appends original filenames with a variant-specific string in the following format: id-{victim ID}.[chivas@aolonline.top].arena. The variable part is a unique identifier assigned to the infected user. It consists of eight hexadecimal characters. Ultimately, the ransomware turns a file named Sample.docx into something like Sample.docx.id-CFABE140.[chivas@aolonline.top].arena.

The email address provided in square brackets may vary too as it matches a specific attacker’s contact details. The thing is, the Crysis/Dharma ransomware is being distributed by several cybercriminal rings that run independent campaigns, hence different contact information of each group. Some of the most widely reported emails, aside from the one mentioned above, include:

• m.heisenberg@aol.com
• macgregor@aolonline.top
• black.mirror@qq.com
• btc2017@india.com
• gladius_rectus@aol.com
• sindragosa@bigmir.net
• sir.dragcsa@bigmir.net
• mandanos@foxmail.com

Anyone confronted with this file-encrypting malware strain therefore gets some clues on what to do next, at least in terms of contacting the threat actors via email.

Victim interaction through filename components alone, though, is definitely scarce. So the Arena ransomware also sprinkles rescue notes across the contaminated system. These are files with detailed instructions on paying the ransom and restoring the skewed data. The Crysis version in question uses the following combo for this purpose: Info.hta and FILES ENCRYPTED.txt. The latter says, literally, “All your data has been locked us. You want to return? Write email chivas@aolonline.top,” or whatever the address is. The latter file, the HTA one, gets displayed automatically due to an autorun task and includes much more information than the TXT counterpart. It reads, “All your files have been encrypted due to a security problem with your PC. If you want to restore them, write us to the email.” At the end of the day, the victim is instructed to shoot a message to the crooks, indicating their personal ID in the email title. The felons will then get back to the user with the size of the ransom and the Bitcoin wallet address to submit it.

The .arena file variant of the Crysis ransomware most commonly propagates via hacked remote desktop services. A lot of people use default or ridiculously easy-to-guess RDP credentials, and online perpetrators definitely know it. Having landed onto a system, the infection attempts to delete shadow copies of the victim’s files in order to prevent this vector of recovery. To top it off, the pest leverages best practices of data encryption, so there is no way to decrypt files for free at this point. However, in case the Arena virus fails to disable VSS, chances are some files can be restored to their normal state. See below for additional details.

Arena ransomware automated removal and data recovery

When faced with ransomware like Arena, 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 Arena 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.

Arena 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 Arena 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 .arena 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 Arena 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 Arena removal tool