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“Your personal files are encrypted by CTB Locker”: decrypt and remove ransomware virus

3 min read
Be updated on all known editions of CTB-Locker, a nasty crypto ransomware program encoding victims’ data and extorting Bitcoins in exchange for decryption.

According to the threat actors’ ads posted on darknet forums back in 2014, CTB is an acronym for “Curve-Tor-Bitcoin”. This malicious file-encrypting entity is a real old stager on the cyber blackmail arena. It was the first Trojan of its kind that introduced built-in affiliate support, which means that this sample pioneered in the Ransomware-as-a-Service (RaaS) domain. Even though the most massive propagation campaign for its predecessor CryptoLocker ended via the FBI’s Operation Tovar two years ago, the same cybercriminal group stayed on this well-trodden track and crafted the new, more advanced sample in question. CTB Locker is known for concurrent circulation of multiple copycats, but they are all equally harmful because the code is shared among several syndicates in Eastern Europe.

CTB-Locker warning message in the desktop background
CTB-Locker warning message in the desktop background

With some external differences across these ransomware versions in place, the invariable thing is the AllFilesAreLocked alert displayed to victims, which is a BMP item that replaces the desktop background. It says, “Your personal files are encrypted by CTB-Locker. Your documents, photos, databases and other important files have been encrypted with strongest encryption and unique key, generated for this computer. Private decryption key is stored on a secret Internet server and nobody can decrypt your files until you pay and obtain the private key.” This warning message also displays a countdown script that shows the amount of time left from the original payment deadline of 96 hours. The malware operators want 0.2 Bitcoin, or about 130 USD, for the file recovery assistance. This sum may vary as different distributors have different mercantile appetites. Up to 5 files can be decrypted for free.

Payment demands of CTB-Locker
Payment demands of CTB-Locker

Having intruded on a Windows machine through a malicious file attached to a phishing email, CTB Locker scans all local drives for popular types of data and then applies elliptic curve cryptography (ECC) to encrypt all those files. The earlier versions of this hoax would append the .CTBL or .CTB2 extension to encrypted files. Later on, though, the perpetrators switched to the use of random extensions. The Trojan also drops icons for ransom payment instructions on the desktop and adds those to every folder with ciphered data. Along with the above-mentioned BMP image, these are named DecryptAllFiles [victim ID].txt and [random].html. Ultimately, the victim is redirected to a Tor page designed to accept and process the ransom payments.

The encryption used by CTB Locker is too strong to get around, furthermore the malefactors implemented it immaculately. Recently, a new iteration appeared that encrypts the content of websites and demands 0.4 Bitcoin for the private key. This is one of the most sophisticated strains to date. The best-case scenario is where the user or webmaster has backups of their important data, in which case they can simply remove the ransomware and download unaffected copies of files from an offsite storage. Otherwise, there are two options: to pay up, or try to use workarounds below.

Automated removal of CTB-Locker ransomware

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 “Your personal files are encrypted by CTB Locker” 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 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 “Your personal files are encrypted by CTB-Locker” 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 CTB Locker 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 CTB Locker ransomware removal tool

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