Gerosan Virus - How to remove

Gerosan is one of many viruses which restrict people’s access to their files by corrupting the data on their disk (or rather, encrypting it and hiding the decryption key). Gerosan belongs to the STOP/DJVU ransomware family and can be recognized by how it appends “.gerosan” to the name of each encrypted file. A Gerosan infection can halt all of your work because you cannot use your files or your computer normally.

The files are renamed and encrypted using hybrid encryption. Encrypting your files is useful for keeping their contents private — only you know the password to unlock the files that you encrypted. But when Gerosan does this to your data, the password — the decryption key — is stored with the criminals. This is what they’re asking money for in their ransom note (a text file called _readme.txt — its text is the same as the other STOP/DJVU viruses: Myskle, Drume, DJVU).

Removing Gerosan is necessary to be able to use your computer normally again, and can be done with a good antivirus program. If Gerosan isn’t removed, it can encrypt all of your new files, too. After Gerosan is removed, you can try to restore the files — remember, paying the criminals is not the only way to restore your files. It’s also good to be aware of the ways that Gerosan spreads to be able to avoid malware in the future.

How to remove Gerosan

This can be done using a powerful antivirus program: Spyhunter, or another reputable application. If your currently installed antivirus tool isn’t detecting Gerosan, that’s because viruses in this family can change the settings of your antivirus, basically making it powerless — that’s why it’s worth using a new antivirus tool for this task. Don’t be surprised if the scan finds more malware than Gerosan, as the virus is often distributed together with other malware.

If there are some websites that you unexpectedly can’t access, Gerosan might have changed some other settings: check this guide for the solution. The encrypted files are safe to keep, you don’t need to delete them.

How to restore your files

If you have backups of your important files, you don’t need to worry. An external drive, cloud storage, or another place your files were saved that was not connected to the infected computer should be safe from Gerosan and the files should be okay — you can simply move them to your computer. However, there are a few things to try to restore the files which didn’t have copies made of them.

First of all, there is a person known as @demonslay335 who uses his time to develop and maintain a program especially for decrypting files that were corrupted by the STOP/DJVU family ransomware. The problem is that only files that were encrypted using the offline key (when the virus was unable to communicate to the Gerosan’s server) are decryptable. Try STOPDecrypter (direct download) and thank Demonslay335 if it worked. Otherwise, read on.

There are also ways to restore your deleted data, either by restoring your system or using data recovery software to uncover deleted files. These ways are outlined in the guide below this article. I should mention that there is no guarantee that they’ll restore all of your files, but they could definitely help.

Paying the criminals money is the last thing you should do in this situation. Consider how unreliable online extortionists are — only three in five people who paid the ransom restored their files. $490 ($980 if you delay by a few days) is a lot of money to spend on that sort of uncertainty, especially when some online extortionists have taken money and, instead of restoring the files, just demanded more.

 

How Gerosan spreads

In general, viruses need someone to download and run them. They often trick people into doing that by pretending to be some safe, wanted file. With the name of some wanted program, or by hiding in an unsuspicious file, Gerosan can end up being run by the owner of the computer unknowingly.

Some legitimate-looking free programs that you downloaded shortly before the infection could be at fault. Gerosan can be hiding in wanted software, waiting for people to download it. If you recently pirated some files, Gerosan might have been hiding there — Gerosan’s sibling viruses are known to be spread disguised as software cracks.

The infected files can be disguised simple documents, too. That’s why sometimes, e-mails are used to spread ransomware. Generic spam e-mails talk about a bill, an invoice, or some other urgent matter, and attach a file, an archive, or a download link that ends up introducing Gerosan to your system.

It’s good to be suspicious of the files that you download, scan them, check their metadata. Don’t open suspicious files at all, to be safe. Update your antivirus program, your operating system, and your browser regularly. Most importantly, keep a backup of your files. You might not be able to avoid viruses altogether, but you can make sure that the impact is minimal.

How to recover Gerosan Virus 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 Gerosan has infiltrated to your system and then click “Next”.
• To start System restore click “Yes”.

 

Step 2. Complete removal of Gerosan Virus

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 Gerosan. You can check other tools here.  

Step 3. Restore Gerosan Virus 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 Gerosan 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 Gerosan Virus 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.