Home Guides GandCrab v5.1 ransomware decryptor and removal [Feb 19 upd.]

GandCrab v5.1 ransomware decryptor and removal [Feb 19 upd.]

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GandCrab 5.1 continues the evolution of the major ransomware plague, now accommodating faster encryption and still posing an extremely high risk to victims.

[Feb 19, 2019 update – decryptor released!]

  1. What is Gandcrab v5.1 ransomware?
  2. GandCrab 5.1 ransomware automated decryption and data recovery
  3. GandCrab 5.1 ransomware manual removal and file recovery
  4. Ransomware Prevention Tips


What is GandCrab 5.1 ransomware?

GandCrab v5.1 is both a run-of-the-mill and exceptional ransomware strain at the same time. Like mainstream crypto viruses out there, it propagates behind a victim’s back, encrypts all valuable data on the infected host, and then demands a certain amount of cryptocurrency for decryption. This is a common practice that’s been feeding cybercriminals for many years on end. What makes this particular malady one of a kind, though, is that it represents a family operated by high-profile attackers boasting outstanding competence in malware distribution, cryptography, and self-anonymization. Having been launched in early 2018, GandCrab has suffered a seizure of Command and Control servers, and recently a release of a free decryptor by a renowned antimalware lab. Yet, it’s still afloat and keeps producing spinoffs.

GandCrab 5.1 can be identified by a number of hallmarks. Similarly to its forerunner GandCrab v5.0.4, it appends a random-looking extension to every encrypted item without changing the filename itself. The length of this suffix varies, but it’s mainly a string of 6-10 characters. Therefore, a spreadsheet Test.xlsx will be renamed to Test.xlsx.hbenfmdmca or something like that. Also, the infection leaves a ransom message whose name includes an uppercase variant of the newly assigned victim-specific extension. It will therefore look similar to HBENFMDMCA-DECRYPT.txt.

GandCrab v5.1 decryption instructions file
GandCrab v5.1 decryption instructions file

The offending code also changes the desktop wallpaper to a warning message as shown in the screenshot.

GandCrab 5.1 replaces desktop wallpaper with an alert image
GandCrab 5.1 replaces desktop wallpaper with an alert image

Speaking of the above-mentioned decryption breakthrough, the tool supports ransomware versions up to GandCrab 5.1 (as of February 2019). The crooks, though, were quick enough to make an overhaul of their crypto implementation in the next ransomware build, eliminating the flaw that allowed the white hats to overcome the cipher in the first place. So, now the victims are face to face with the ruthless digital adversary. The following description of this infection’s modus operandi is, therefore, useful both for those attacked and for the users who want to keep their data safe.

GandCrab 5.1 is doing the rounds in several different ways. The dominating technique remains unaltered – it’s the tried-and-tested spam. The culprits engage the mass-mailing power of a botnet to send rogue emails to numerous users. While the messages proper are safe, the attachments aren’t. Those are typically booby-trapped documents that go with macros whose goal is to fire up a JavaScript code in a surreptitious fashion. This way, the ransomware binary and other components are downloaded onto the computer. One more spreading mechanism that’s gearing up for a rise endangers users who go the slippery slope of foul play with app activation. In this case, the contagion is a crack tool for popular software suites, such as Microsoft Office. The workflow is trivial: a person downloads and launches code masqueraded as a crack solution, which is actually the GandCrab 5.1 binary in disguise. A few seconds elapse, and the ransomware is on board.

Having spotted the bulk of valuable data on the contaminated machine’s HDD and network drives, the perpetrating program locks it down using its enhanced crypto algorithms. A big tweak that took effect in GandCrab 5.1 variant is that the encryption speed has increased. The next thing you know, the names of all personal documents, databases, videos, photos and other important files are stained with a new extension. Again, it’s a random string of characters that’s unique to the specific victim. The frightening desktop wallpaper says, “Encrypted by GandCrab 5.1” and includes a reference to the TXT ransom note. The latter, in its turn, contains a Tor link for the victim to follow, which leads to the payment page. It lists two payment options (via Bitcoin or Dash cryptocurrency), provides the criminals’ BTC wallet address, and additionally displays information on the deadline before the ransom size doubles.

GandCrab payment page contains a hidden discount code feature
GandCrab payment page contains a hidden discount code feature

So much for the tactic of GandCrab 5.1. What should the victims do? Unfortunately, a free decryption tool has yet to be released – at least, it’s not available at the time of this writing. Sending the ransom is definitely not in the user’s best interest, because it means the bad guys win. That’s a lot of money, too. The amount can be $800 worth of BTC or DSH, but it can as well reach sums multiple times more than that.

Interestingly, security analysts have recently unearthed the involvement of an intermediary link in the ransom-based file decryption procedures, and it’s not about the RaaS (Ransomware-as-a-Service) model alone. The operators of GandCrab turn out to have enhanced their revenue acquisition practices by adding unethical data recovery companies to the mix. Such firms have been negotiating with the extortionists in order to get “discount” codes for the ransoms, and the crooks are reportedly willing to collaborate.

In case the deal works out, a questionably unscrupulous “partner” will advertise the recovery service across multiple marketing channels, including YouTube and social media. GandCrab 5.1 victims who stumble upon one of such ads may get interested and opt for the assistance. The catch is, the dubious recovery company will ask for a higher ransom than the cybercriminals demand. Furthermore, they will enter the previously obtained “promo” code in an obfuscated section of the support chat available on the GandCrab Tor payment page in order to get an extra 5-20% off.

It means that the black hats sitting at the top of the ransomware food chain get their profit, and so do the unprincipled intermediary companies that charge the victims an additional fee while also benefiting from the discounted size of the ransom. The only losing party in this scenario is the infected user. Under the circumstances, it’s certainly recommended to try some of the best practices of forensic data recovery first without resorting for pseudo help of ne’er-do-wells.

GandCrab 5.1 ransomware automated removal and data recovery

Owing to an up-to-date database of malware signatures and intelligent behavioral detection, BitDefender decryption tool v1.1 can quickly locate the infection, eradicate it and remediate all harmful changes.

>Download Bitdefender ransomware decryption tool v1.1

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


GandCrab 5.1 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 GandCrab 5.1 blackmail 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.

Remove GandCrab 5.1 ransomware using Safe Mode with Networking

Remove GandCrab 5.1 ransomware using Safe Mode with Networking

Boot into Safe Mode with Networking. The method to do it depends on the version of the infected operating system. Follow the instructions below for your OS build.

  • Restart the machine. When the system begins loading back up, keep pressing the F8 key with short intervals. The Windows Advanced Options Menu (Advanced Boot Options) screen will appear.Boot into Safe Mode with Networking on Windows Vista and 7
  • Use arrow keys to select Safe Mode with Networking and hit Enter. Log on with the user account infected by the ransomware.
  • Click on the Search icon next to the Start menu button. Type msconfig in the search field and select the System Configuration option in the results. Go to the Boot tab in the upper part of the GUI.Boot options on Windows 8, 8.1 and 10
  • Under Boot options, select Safe boot and click the Apply button. A prompt will appear to reboot the computer so that the changes take effect. Select the Restart option and wait for the system to load into Safe Mode. Again, log on with the ransomware-stricken user account.

In Safe Mode, the ransom Trojan won’t keep security software from running or otherwise thwart troubleshooting. Open your preferred web browser, download and install an antimalware tool of choice and start a full system scan. Have all the detected ransomware components removed in a hassle-free way.

Get rid of GandCrab 5.1 ransomware using System Restore

Get rid of GandCrab 5.1 ransomware using System Restore

System Restore enables Windows users to roll back all changes made to the OS since the latest restore point creation time. This feature can help eliminate the most persistent ransomware. Before going this route, though, make sure System Restore had been enabled prior to the breach, otherwise the method will be inefficient.

  • Open Windows Advanced Options Menu as described in the previous section: hit F8 repeatedly when the PC is starting up. Use arrow keys to highlight the Safe Mode with Command Prompt entry. Hit Enter.Safe Mode with Command Prompt
  • In the Command Prompt window, type cd restore and hit Entercd restore command
  • Type rstrui.exe in the new command line and press EnterType rstrui.exe command
  • When the System Restore screen pops up, click Next, select a restore point that predates the contamination, and use the application’s controls to roll back the system to this earlier state.System Restore window

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 files encrypted by GandCrab 5.1

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

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 GandCrab 5.1 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

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

Alternatively, you can leverage the Previous Versions feature, which is native to Windows operating system. This method is more cumbersome that the use of ShadowExplorer, but it can help restore the most important individual files on condition that the ransomware failed to disable the Volume Snapshot Service on the computer. Right-click on a file of choice and select Properties. Then, go to the Previous Versions tab as illustrated below.
Previous Versions

Go ahead and pick the file’s latest backup version on the list. Use the Copy or Restore buttons to reinstate this object to a new path or to its original folder, respectively.


Ransomware Prevention Tips

To avoid GandCrab 5.1 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 GandCrab 5.1 ransomware removal tool

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3 Comments

  1. Val Trinity

    February 7, 2019 at 10:40 am

    Does BitDefender Decryption Tool work for Gandcrab v5.1?

    Reply

  2. WI

    February 14, 2019 at 9:24 am

    No they have already mentioned that it wont work beyound version 5.0.3.

    Reply

  3. Will Wisser

    February 21, 2019 at 5:17 pm

    Val, BitDefender Decryption Tool now does the job for 5.1 too!

    Reply

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