Cdtt ransomware is a member of the STOP/DJVU ransomware group, known for encrypting files on infected systems and demanding a ransom in exchange for the decryption key. If your system has been hit by the .cdtt virus, you're likely unable to access your files. Here’s how you can deal with the infection, based on guidance from MiniTool.

What Is Cdtt Ransomware?

Ransomware attacks have grown increasingly common and damaging in recent years. One prominent example is the Cdtt ransomware, part of the widespread STOP/DJVU family. This malware infiltrates systems and begins encrypting personal files such as photos, videos, documents, and more.

Once encrypted, each file gets the “.cdtt” extension added to its name—turning “1.png” into “1.png.cdtt” and “2.docx” into “2.docx.cdtt”, for example. As a result, these files become unreadable without the decryption key.

The attackers leave a ransom note titled “readme.txt” on the desktop, demanding payment in Bitcoin—typically between $490 and $980—to unlock the files. Victims are instructed to contact the cybercriminals via two provided email addresses: [email protected] and [email protected].

This variant uses the Salsa20 encryption algorithm, which is extremely difficult to reverse without the original key. While there have been some successful decryption attempts using leaked or cracked keys, the chances remain slim. Failure to pay within the given time may lead to threats of higher ransoms or permanent data loss.

If you notice files with the .cdtt extension and can no longer open them, your device is likely infected. Don’t panic—follow the steps below to respond effectively.

Back Up Unaffected Files

As soon as you detect the presence of Cdtt ransomware, immediately back up any files that haven’t been encrypted yet. This helps preserve your data in case the malware continues spreading.

Use an external hard drive or USB flash drive to store the backup, ensuring it’s disconnected after the process to avoid contamination.

For reliable backup, consider using MiniTool ShadowMaker, a powerful tool offering automated backups, including incremental and differential options. It works across Windows 11, 10, 8.1, 8, and 7. You can try the Trial Edition for free.

Steps to back up your data:

1. Plug in your external storage device to the infected PC.
2. Launch MiniTool ShadowMaker and click Trial Edition.
3. Go to Backup, then select SOURCE > Folders and Files to choose what to back up.
4. Click DESTINATION to set the external drive as the save location.
5. Hit Back Up Now to start the process.

How to Eliminate the .Cdtt Virus

Step 1: Disconnect from the Network

To stop the ransomware from spreading to other devices on the same network, disconnect the infected machine immediately.

You can do this by unplugging the Ethernet cable or turning off Wi-Fi. Alternatively, go to Control Panel > Network and Internet > Network and Sharing Center > Change adapter settings, right-click your active connection, and select Disable.

Step 2: Scan and Remove the Malware

Use antivirus software to detect and eliminate the Cdtt ransomware.

Windows 11 and 10 come with built-in protection via Windows Security—run a full system scan to check for threats. For better results, install a third-party solution such as Malwarebytes (preferably in Safe Mode with Networking). Once installed, perform a deep scan and remove any detected malicious components.

Related post: Free Malwarebytes Downloads for Windows/Mac/Android/iOS

Other tools like HitmanPro and ESET Online Scanner are also effective at identifying and removing STOP/DJVU variants like Cdtt.

Step 3: Attempt File Recovery with Emsisoft Decryptor for STOP Djvu

Although most ransomware-encrypted files cannot be recovered, there is a chance—especially if the encryption used an older, vulnerable version.

Emsisoft offers a free decryptor specifically for STOP/Djvu ransomware strains, including Cdtt. Here’s how to use it:

1. Download the Emsisoft Decryptor for STOP Djvu from a trusted source using a clean device if possible.
2. Install and run the tool on the infected PC.
3. Click the Decrypt button to begin scanning and attempting recovery.

Note: Success depends on whether the specific encryption key used by the virus is already known. Newer variants are often not yet decryptable.

Related post: Ransomware Prevention Tips: How to Avoid Infection

Final Thoughts

The Cdtt ransomware (.cdtt virus) is a serious threat that locks your files using strong encryption. If you discover .cdtt files on your system, act quickly: back up uninfected data, disconnect from the network, run antivirus scans, and try decryption tools. While full recovery isn’t guaranteed, prompt action can limit damage and improve your chances of restoring your files.

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