Avaddon (avdn) Ransomware - How to remove

Avaddon is ransomware that encrypts files. It’s relatively new, but it’s already pretty well known. It comes in malicious attachments that arrive with spam emails. Once Avaddon is downloaded and installed, it steals some data, locks files and marks them with the avdn extension. Avaddon asks hundreds of dollars from each victim if they want to get their files back. So far, there doesn’t appear to be a way to decrypt files for free.

Update: Emsisoft has released a decryptor for Avaddon. The ransomware still needs to be removed to avoid repeat encryption, but now you can recover the encrypted files!

About Avaddon:

Type of threat	Ransomware.
Avaddon symptoms	Files don’t open and have “avdn” as their extension, the desktop background picture changes, restore points and other backups are gone.
How to get the files back	Restore them from a backup, undelete files, repair corrupted files.
How to delete Avaddon	Use antivirus programs (like Spyhunter), make sure that security updates are installed.

What is Avaddon

Main features

Avaddon is a pretty new ransomware, so not everything is yet known about it. Here are some signs of an Avaddon infection:

• Files have a second extension appended to their names – so, “picture.jpg” becomes “picture.jpg.avdn”.
• Ransom notes are left on the infected computer, called [random]-readme.html. They offer something called “Avaddon General Decryptor” for a few hundred dollars (the amount varies).
• The desktop background is changed to an image that says “All your files has been encrypted”.
• Shadow volume copies, restore points are deleted.
• Antivirus programs don’t work or malfunction.
• Currently, Avaddon spreads via malicious spam emails, so the infection must have been preceded by you opening a mysterious email and downloading an attachment.

Data stealer

Avaddon is known for stealing files in addition to encrypting them. The cybercriminals behind this ransomware threaten to publish the stolen data of those victims who don’t pay the extortion.

The free decryptor

At the moment, there’s no known way to recover (decrypt) the files that Avaddon encrypts (that is, without paying the ransom, which is extremely risky and expensive).

A decryption tool was developed for Avaddon ransomware, though it only worked in cases where the victim hadn’t yet turned off their computer. But Avaddon’s developers patched their malware, so the decryptor won’t be good for future victims. Free decrypter released for Avaddon ransomware victims... aaand, its gone!.

If anyone offers to fix your files for a fee, be very careful – likely, they’re a scammer. The Avaddon General Decryptor may be a real decryptor, but it is useless without the correct decryption key, which is unique to each victim.

Distribution

Avaddon spreads in malicious emails. The spam emails can be anything, but according to the AppRiver analysis, a winking smiley and a subject line asking the recipient’s opinion on a photo. The subject line is meant to get people interested in the attachment. The attachment is not a photo, but the downloader for Avaddon. It’s disguised as a safe file with the help of double or triple extensions. For example, a downloader named “picture.jpg.js” would appear as “picture.jpg”, so people might feel safe opening the file. Here is a file that downloads Avaddon uploaded on VirusTotal (look at the file names under the Details tab – it’s a JavaScript file with a double extension).

Avaddon’s creators get away with this because many Windows computers hide the last file extension to prevent people from accidentally editing them (How to Make Windows Show File Extensions).

GandCrab was spreading in infected Doc files. Trojans like Emotet and Sphinx use the same method. Tricking people to open infected files is still very effective. So, it’s not surprising that Avaddon spreads using malicious spam.

If Avaddon continues to be active, it’ll probably be distributed in new ways and targeted more precisely (for example, by impersonating local businesses or hijacking niche websites). That’s likely because people found ads for an Avaddon affiliate program. This means that Avaddon could be distributed as RaaS – Ransomware-as-a-service: independent teams of malicious actors take Avaddon and spread it in their own ways, sharing the profits with Avaddon’s creators. Different extensions for encrypted files could be used.

How to protect yourself

When it comes to ransomware, file backups are the best tool in protecting yourself. Avaddon scans for hidden drives to encrypt, so the backups cannot be connected to the network.

Some other ways to protect yourself not just from ransomware, but from trojans and other malware:

• Do not open mysterious email attachments without scanning them with an antivirus program first.
• Install updates for your OS and other software so that malicious programs can’t use known vulnerabilities.
• Secure remote access to your server with strong passwords, VPN, user account control, etc.
• Use a good spam filter to protect your email.
• Use an antivirus program with real-time protection.
• Make sure your browsing habits don’t expose you to malware.

Removing Avaddon

Make backups of the files that Avaddon encrypted if you want to keep them. These files aren’t dangerous and, don’t hold your breath, but there’s a small chance that some kind of decryption method becomes available (for example, law enforcement catches Avaddon’s developers). Besides, if Avaddon doesn’t encrypt files entirely, then you may be able to use the methods meant for repairing corrupted files to recover a little of your data.

Scan the infected computer with antivirus programs, like Spyhunter. It’s pretty standard for ransomware to also deliver spyware, so don’t be surprised if next to Avaddon, a trojan is discovered. If it is, then it might have stolen some of your passwords, usernames, email contacts, and similar data.

Automatic Malware removal tools

How to recover Avaddon (avdn) Ransomware encrypted files and remove the virus

Step 1. Restore system into last known good state using system restore

1. Reboot your computer to Safe Mode with Command Prompt:

for Windows 7 / Vista/ XP

• Start → Shutdown → Restart → OK.
• Press F8 key repeatedly until Advanced Boot Options window appears.
• Choose Safe Mode with Command Prompt.

for Windows 8 / 10

• Press Power at Windows login screen. Then press and hold Shift key and click Restart.
• Choose Troubleshoot → Advanced Options → Startup Settings and click Restart.
• When it loads, select Enable Safe Mode with Command Prompt from the list of Startup Settings.

 

2.Restore System files and settings.

• When Command Prompt mode loads, enter cd restore and press Enter.
• Then enter rstrui.exe and press Enter again.
• Click “Next” in the windows that appeared.
• Select one of the Restore Points that are available before Avaddon (avdn) Ransomware has infiltrated to your system and then click “Next”.
• To start System restore click “Yes”.

 

Step 2. Complete removal of Avaddon (avdn) Ransomware

After restoring your system, it is recommended to scan your computer with an anti-malware program, like Spyhunter and remove all malicious files related to Avaddon (avdn) Ransomware. You can check other tools here.  

Step 3. Restore Avaddon (avdn) Ransomware affected files using Shadow Volume Copies

If you do not use System Restore option on your operating system, there is a chance to use shadow copy snapshots. They store copies of your files that point of time when the system restore snapshot was created. Usually Avaddon (avdn) Ransomware tries to delete all possible Shadow Volume Copies, so this methods may not work on all computers. However, it may fail to do so. Shadow Volume Copies are only available with Windows XP Service Pack 2, Windows Vista, Windows 7, and Windows 8. There are two ways to retrieve your files via Shadow Volume Copy. You can do it using native Windows Previous Versions or via Shadow Explorer. a) Native Windows Previous Versions Right-click on an encrypted file and select Properties → Previous versions tab. Now you will see all available copies of that particular file and the time when it was stored in a Shadow Volume Copy. Choose the version of the file you want to retrieve and click Copy if you want to save it to some directory of your own, or Restore if you want to replace existing, encrypted file. If you want to see the content of file first, just click Open.

b) Shadow Explorer It is a program that can be found online for free. You can download either a full or a portable version of Shadow Explorer. Open the program. On the left top corner select the drive where the file you are looking for is a stored. You will see all folders on that drive. To retrieve a whole folder, right-click on it and select “Export”. Then choose where you want it to be stored.

Step 4. Use Data Recovery programs to recover Avaddon (avdn) Ransomware encrypted files

There are several data recovery programs that might recover encrypted files as well. This does not work in all cases but you can try this:

• We suggest using another PC and connect the infected hard drive as slave. It is still possible to do this on infected PC though.
• Download a data recovery program.
• Install and scan for recently deleted files.

Note: In many cases it is impossible to restore data files affected by modern ransomware. Thus I recommend using decent cloud backup software as precaution. We recommend checking out Carbonite, BackBlaze, CrashPlan or Mozy Home.