Can antivirus software remove ransomware from my infected system?

Which antivirus software remove ransomware from my computer? Is this possible for any antivirus software?

While an Antivirus/Antimalware program may be able to remove the malware files from your machine, it will not, as a general rule, be able to reverse any encryption that the malware performed on your data.

In fact, depending on the flavor of ransomware, removing the malware may make data recovery more difficult or impossible. So, we don't generally recommend that you do this.

I'd recommend posting in the topic corresponding to the type of ransomware you have been infected with. If you don't know what kind, you can check out this topic. https://www.bleepingcomputer.com/forums/t/608858/id-ransomware-identify-what-ransomware-encrypted-your-files/

~Blade

Removing Ransomware From An Infected Computer:

 

Most crypto malware ransomware is typically programmed to automatically remove itself...the malicious files responsible for the infection...after the encrypting is done since they are no longer needed but there are some exceptions. The malware developers most likely do this to make it more difficult for security researchers to find and analyze their malicious payload. That also explains why many security scanners do not find anything after the fact. The encrypted files do not contain malicious code so they are safe. Unfortunately, most victims do not realize they have been infected until the ransomware displays the ransom note and the files have already been encrypted. In some cases there may be no ransom note and discovery only occurs at a later time when attempting to open an encrypted file. As such, many victims don't know how long the malware was on the system before being alerted or if other malware was downloaded and installed along with the ransomware which could still be present on the infected computer.

Some crypto malware (i.e. STOP/Djvu Ransomware) are known to leave behind malicious components that will encrypt any new files saved and re-encrypt any files victims previously managed to decrypt. Other ransomware (i.e. Phobos Ransomware) are very aggressive and do not end on a single run...they will run multiple times ensuring repeated infection. There are a few ransomwares that will store a victim's master key in the registry and if removed, the next time the computer is restarted, the ransomware could create a new master key and begin encrypting files again. That means encrypted data by two different keys.
 

Therefore it is recommended to isolate the infected computer from other devices and thoroughly check the system to ensure no such malicious components have been left behind. IT folks and advanced users who are ransomware victims can use Farbar Recovery Scan Tool (FRST), an advanced specialized tool designed to investigate for the presence of malicious and suspicious files. FRST logs provide detailed information about your system, registry loading points, services, driver services, Netsvcs entries, known DLLs, drives, partition specifications and will also list system files that could be patched by malware.

There are a few ransomware variants that will add an entry to Run and RunOnce Registry Keys so the malicious executable or ransom screen always displays itself on each restart of the computer. In such cases, victims should look for a related entry under the Startup tab in Windows System Configuration Utility (msconfig) or use a tool such as Autoruns to search for and remove any malicious entries.

 

When dealing with ransomware removal it is best to quarantine malicious files rather than delete them until you know or confirm what infection you're dealing with. In some cases, samples of the malware itself are needed for further analysis in order to identify it properly or investigate for flaws which could lead to the creation of a decryption tool so your data can be recovered. Quarantine is just an added safety measure which allows one to view and investigate the files while keeping them from harming your computer. If using security scanning disinfection tools, system optimization and/or cleanup software on some ransomware before backing up, there is a chance they could remove related registry keys and malicious files which may be required to recover your data.

 

Important Note: Some ransomware have been known to install password stealing Trojans on victim's computer to steal account credentials, cryptocurrency wallets, desktop files, and more. It is imperative that you change all passwords for your computer to include those used for banking, taxes, email, eBay, paypal and any online activities which require a username and password. You should consider them to be compromised and change passwords from a clean computer as a precaution, not the infected one.

 

If your antivirus did not detect and remove anything, additional scans should be performed with other security programs like Emsisoft Anti-Malware, Emsisoft Emergency Kit, Malwarebytes, Zemana AntiMalware or RogueKiller Anti-malware.

• How to Perform Manual Ransomware Removal
• How to remove ransomware the right way: A step-by-step guide
• The Basics of Manual Malware Identification and Removal
• Emsisoft: How do I remove the ransomware?
• How To Safely Store Ransomware Encrypted Files
• First steps when dealing with ransomware

If the computer was shut down to prevent it from encrypting any more files as explained here, then you can use Kaspersky RescueDisk or similar LiveCD/Rescue utilities to assist with malware removal without having to boot into Windows. Offline scanning is a method to disinfect malware from outside an infected Windows system environment by using an anti-malware program that runs outside of the traditional operating system. Offline scanners are usually self-contained, do not require a network or Internet connection and are typically loaded onto a flash drive or CD/DVD and set to boot prior to the operating system. The advantage of offline scanning tools is that they can be used when the malware is not running and interfering with the clean-up process.

• Why And When You Might Need an Offline Malware Scanner

Note: Disinfection will not help with decryption of any files affected by the ransomware.
 
Before doing anything, if possible it is recommended to backup or create a copy or image of the entire hard drive. Doing that allows you to save the complete state of your system. Imaging the drive backs up everything related to the infection including encrypted files, ransom notes, key data files (if applicable) and registry entries containing possible information which may be needed if a decryption solution is ever discovered. The encrypted files and ransom note text files do not contain malicious code so they are safe. Alternatively, you can remove the hard drive, store it away and replace it with a new hard drive.
 
Of course you can always choose to reinstall/refresh/reset Windows, perform a factory reset or reformat instead which will remove ransomware related malicious files...it also will erase all the data on your computer to include your encrypted files, ransom notes, any programs you installed and the settings on your computer so backup your important data first even if it is encrypted. Reinstalling will essentially return the computer to the same state it was when you first purchased and set it up to include any preinstalled and trial software provided by the vendor. However, there are boot sector viruses (bootkits) which can alter the Master Boot Record (MBR) as explained here and in those cases, you should also rewrite the MBR to ensure all malicious code has been removed.

 

If you have an older operating system you may need to reformat the hard drive.

• What Does Format Mean?
• What does it mean to reformat a hard drive?
• How to Erase and Format a Hard Drive

It never hurts to try a manual clean-up first with trustworthy security scanning tools if that is something you want to consider. However, it is still recommended to create a copy or image of the entire hard drive before doing anything for the same reasons noted above.
 
If you need individual assistance only with removing the malware infection, there are advanced tools which can be used to investigate and clean your system. Please follow the instructions in the Malware Removal and Log Section Preparation Guide...all other questions or comments should be posted in the support topics. When you have done that, start a new topic and post your FRST logs in the Virus, Trojan, Spyware, and Malware Removal Logs forum, NOT here, for assistance by the Malware Response Team.

 

Ransomware victims should ignore all Google searches which provide numerous links to bogus and untrustworthy ransomware removal guides, including Facebook and YouTube videos, many of which falsely claim to have decryption solutions. After expert researchers write about a new ransomware or new variants, junk articles with misinformation are quickly written in order to scare and goad desperate victims into using or purchasing mostly sham removal and decryption software. Victims typically are directed to download a multitude of unnecessary and useless tools. In some cases, unsuspecting victims may actually be downloading a fake decryptor with more ransomware resulting in double-encryption that makes the situation even worst. Further, your personal and financial information are also at risk when dealing with scammers. Only use trusted sources when searching for information.

 

Updated: 11/12/23

The best defensive strategy to protect yourself from malware and ransomware (crypto malware) infections is a comprehensive approach to include prevention. Make sure you are running an updated anti-virus and anti-malware product, update all vulnerable software, use supplemental security tools with anti-exploitation features capable of stopping (preventing) infection before it can cause any damage, disable VSSAdmin, close Remote Desktop Protocol (RDP) if you do not need it and routinely backup your data.

Security is all about layers and not depending on any one solution, technology or approach to protect yourself from cyber-criminals. The most important layer is you...the first and last line of defense. No amount of security software is going to defend against today's sophisticated malware writers for those who do not practice safe computing and stay informed. It has been proven time and again that the user is a more substantial factor (weakest link in the security chain) than the architecture of the operating system or installed protection software.

For more suggestions to protect yourself from malware infection, see my comments (Post #14) in this topic...it includes a list of prevention tools.

What about encrypted files? Can they be decrypted in any way? 

What about encrypted files? Can they be decrypted in any way?

Whether you can recover (decrypt) your files or not depends on what ransomware infection you are dealing with, the type and strength of encryption used by the malware writers and a variety of other factors as explained in this topic.