Home Guides Decrypt and remove CrypMIC/CryptMIC ransomware

Decrypt and remove CrypMIC/CryptMIC ransomware

3 min read
Find out how to get around the data encryption by CrypMIC / CryptMIC ransomware, learn what other infection it resembles and get the attack workflow details.

When the CrypMIC ransomware campaign broke out in late July 2016, it instantly drew the attention of security experts. Also dubbed CryptMIC, this computer threat bears a resemblance to an older file-encrypting Trojan known as CryptXXX. A striking similarity can be observed in the distribution technique, the contents and design of ransom instructions, as well as the ransom size. Both of these offending programs are being deposited on PCs via the Neutrino exploit kit. The amount of money that victims are required to pay for recovering their personal data is 1.2 Bitcoins in either case, and it becomes twice as big if the user fails to submit it during 100 hours since the attack commenced. Meanwhile, the attributes that aren’t shared between these samples include the encryption algorithm applied, the names of recovery notes, and the way CrypMIC handles filenames of encoded items.

HTML warning by CrypMIC
HTML warning by CrypMIC

More specifically, CryptMIC leverages the symmetric AES-256 algorithm to lock one’s data, although it deceptively states in the warning messages that the cipher is asymmetric RSA-4096. The difference being drastic, both AES and RSA are virtually uncrackable if deployed properly. One way or another, the files locked by this ransomware cannot be completely restored without the master key owned by the attackers. Regarding the documents that contain restoration directions, they are named Readme.html, Readme.txt and Readme.bmp. The corresponding icons are added to the infected computer’s desktop and all folders with corrupted files. The main message therein is as follows, “All of your files were protected by a strong encryption with RSA4096,” which is partly a bluff as far as the actual cryptosystem is concerned.

README.txt providing decryption steps
README.txt providing decryption steps

As opposed to CryptXXX, CrypMIC does not alter the names of encrypted entries. This means that no specific extension is appended, nor are the filenames scrambled either. This approach makes it problematic for a victim to figure out what exactly has been affected on the hard drive and network shares – the only way to find out is by trying to open a specific item, which will return an error. In order to get the data back to its accessible state, the infected user is supposed to install Tor Browser and visit one of the two .onion pages listed in the Readme.html (.txt, .bmp) files. The site titled “Decryption service” then tells the person to enter their personal identification code, which is also provided in the ransom notes. It is a string consisting of 4 blocks of 8 hexadecimal characters separated by colons.

Having thus logged into the service, the victim will see how much time they have left before the ransom goes from 1.2 BTC to 2.4 BTC, their operating system and IP address details, as well as the information on the Bitcoin wallet that the digital cash should be sent to. Interestingly enough, CrypMIC claims to upsell a product called the “Microsoft decryptor”, which is the alleged restoration tool. Whereas there is currently no free decrypt solution for files skewed by this threat, a couple of techniques may come in handy to revive some information.

Automated removal of CrypMIC / CryptMIC virus

Owing to an up-to-date database of malware signatures and intelligent behavioral detection, the recommended software can quickly locate the infection, eradicate it and remediate all harmful changes. So go ahead and do the following:

1. Download and install the antimalware tool. Open the solution and have it check your PC for PUPs and other types of malicious software by clicking the Start Computer Scan button

Download CrypMIC / CryptMIC virus remover

2. Rest assured the scan report will list all items that may harm your operating system. Select the detected entries and click Fix Threats to get the troubleshooting completed.

Ways of non-ransom recovery of CrypMIC encrypted 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.

Backups can make your day

Not only are you a lucky person in case you’ve been backing up your most important files, but you’re also a wise and prudent user. This isn’t necessarily a resource-heavy activity these days – in fact, some providers of online services are allocating a sufficient size of cloud storage space for free so that every customer can easily upload their critical data without paying a penny. Having removed the ransomware, therefore, all you have to do is download your stuff from the remote server or transfer it all from an external piece of hardware if that’s the case.

Restore previous versions of encrypted files

A positive upshot of using this technique depends on whether or not the ransomware has erased the Volume Shadow Copies of the files on your PC. This is a Windows feature that automatically makes and keeps the backups of data elements on the hard drive as long as System Restore is enabled. The cryptoware in question is programmed to switch off the Volume Shadow Copy Service (VSS), but it has reportedly failed to in some cases. Checking one’s options regarding this workaround is doable in two ways: through the Properties menu of each file or by means of the remarkable open-source tool called Shadow Explorer. We recommend the software-based way because it’s automated, hence faster and easier. Just install the app and use its intuitive controls to get previous versions of the encrypted objects reinstated.
Shadow Explorer

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 Data Recovery Pro by ParetoLogic features this type of capability therefore it can be applied in ransom attack scenarios to at least get the most important files back. So download and install the program, run a scan and let it do its job.

Download Data Recovery Pro

Data Recovery Pro

Ransomware Prevention Tips

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

  • Toggle your email provider’s anti-spam settings to filter out all the potentially harmful incoming messages. Raising the bar beyond the default protection is an important countermeasure for ransom Trojans

  • Define specific file extension restrictions in your email system. Make sure that attachments with the following extensions are blacklisted: .js, .vbs, .docm, .hta, .exe, .cmd, .scr, and .bat. Also, treat ZIP archives in received messages with extreme caution

  • Rename the vssadmin.exe process so that ransomware is unable to obliterate all Shadow Volume Copies of your files in one shot

  • Keep your Firewall active at all times. It can prevent crypto ransomware from communicating with its C&C server. This way, the threat won’t be able to obtain cryptographic keys and lock your files

  • Back up your files regularly, at least the most important ones. This recommendation is self-explanatory. A ransomware attack isn’t an issue as long as you keep unaffected copies of your data in a safe place

  • Use an effective antimalware suite. There are security tools that identify ransomware-specific behavior and block the infection before it can do any harm.
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.

Download CrypMIC ransomware removal tool

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