Ransomware is a type of malicious software that encrypts files on a computer and demands payment to decrypt them. Unfortunately, ransomware has become increasingly common, with attacks targeting both individuals and organizations. When infected with ransomware, victims face the difficult decision of whether to pay the ransom or try restoring their files through other means. Many security experts advise against paying, as it encourages and funds criminal activity. However, recovering encrypted files without the decryption key provided by the attackers is often challenging. This article examines methods for removing ransomware and restoring encrypted files for free.
Can anti-virus software remove ransomware?
Most anti-virus programs detect and remove known ransomware strains during scans. However, they may struggle with new, unknown variants. Additionally, if ransomware is already running on a system, it may disable anti-virus software. So anti-virus alone is not sufficient protection against ransomware. Still, keeping your anti-virus updated and running regular scans can catch some ransomware infections early.
Using anti-ransomware software
There are security tools specialized for detecting ransomware behavior and protecting against attacks. These anti-ransomware programs monitor system activity to recognize ransomware’s distinct actions like encrypting files or preventing other applications from running. When ransomware activity is identified, the anti-ransomware software can stop the attack and prevent file encryption. Examples of anti-ransomware tools include Bitdefender Anti-Ransomware, Acronis Ransomware Protection, and McAfee Ransomware Interceptor.
Strengths
- Designed specifically to detect ransomware activity
- Can recognize new ransomware strains based on behavior
- Can stop encryption process before files are locked
Limitations
- Must be installed and running before infection occurs
- Unknown ransomware may still slip past defenses
- Requires a paid license for real-time protection
Using bootable anti-malware tools
If ransomware is already active on a system, running anti-malware scans directly on the infected operating system likely will not remove it. However, bootable anti-malware tools provide a workaround. These tools allow you to boot your computer from a USB drive into a special environment isolated from the regular operating system. Since the ransomware only affects the main OS, bootable tools can scan the system without interference.
Popular bootable anti-malware tools like Kaspersky Rescue Disk, Avira Rescue System, and Bitdefender Antivirus Rescue CD provide complimentary downloads. To use them, first download and install the software on a USB drive. Then boot the infected computer from the USB. The drives contain updated malware libraries capable of detecting and removing many ransomware strains. After cleansing, reboot normally and assess the damage. While useful in some situations, bootable tools have limitations:
Strengths
- Avoids ransomware interference during scans
- Included anti-malware libraries can identify known strains
- Freely available for download and easy to create
Limitations
- Requires an uninfected system to create the USB drive
- May miss new or rare ransomware variants
- Cannot restore encrypted files, only remove infection
Leveraging cloud storage and backups
Another free method that may recover some encrypted files uses cloud storage and external backups. Most ransomware targets local files stored on the system’s hard drive. However, many users also sync or back up files to cloud storage services like OneDrive, Google Drive, Dropbox, etc. Ransomware usually cannot access or encrypt cloud-stored files.
Similarly, external backups not continuously connected to the infected system during the attack remain protected. So restoring files from either cloud storage or disconnected external drives can recover portions of lost data. However, this method’s effectiveness depends on having an up-to-date backup. Any changes or new files created locally since the last sync or backup will still be lost. Maintaining continuous, frequent backups to disconnected drives can increase this method’s success.
Strengths
- Recovers files stored remotely outside ransomware’s reach
- Does not rely on detecting/removing the ransomware
- External drives provide offline protection
Limitations
- Only restores files last synced with cloud or backed up locally
- Incomplete protection without comprehensive backup habits
- Does not prevent the ransomware attack itself
Using free decryption tools
For some known ransomware strains, security researchers can recover decryption keys or develop apps that decrypt files. These free tools essentially undo the ransomware’s file encryption after infection. However, most are tailored only to specific ransomware variants. Examples include toolkits that decrypt files affected by Shade, TeslaCrypt, WildFire, and other named families.
Websites like No More Ransom provide an aggregated list of ransomware decryptors available for download. While frequently updated, the list represents only a small subset of ransomware variants. More sophisticated strains like Ryuk, RobinHood, and REvil still lack free decryptors. So while valuable, this method’s effectiveness depends on the ransomware type.
Strengths
- Decrypts files after ransomware attack completes
- Requires no ransom payment
- New tools released as researchers make breakthroughs
Limitations
- Only works for known, decryptable ransomware families
- Not effective against newer, advanced strains
- Requires identifying the specific ransomware variant
Wiping the system and restoring from backup
In severe ransomware infections, the only option may be wiping the system drives entirely. With the infected OS erased, fresh Windows and application installs can reset the computer to a pre-infection state. This removes any ransomware traces, allowing files to be restored from backups unaffected by encryption.
The process begins by backing up any personal files not yet encrypted. Then boot into recovery mode, access advanced startup options, and perform a system restore or reset. Alternatively, use installation media to perform a clean install of Windows. With the drives reformatted and OS restored, reconnect backups and restore personal files.
The downside is this techniques deletes all programs, settings, and data stored locally. Only backups survive. So only consider it a last resort when ransomware encryptsfiles extensively and persists through other removal attempts.
Strengths
- Completely removes ransomware by wiping system
- Allows restoring encrypted files from backup
- Fresh OS install ensures all infections are cleared
Limitations
- Deletes all local programs and data without backups
- Time-intensive reinstallation process
- Requires a clean, non-encrypted system image
Using shadow copies to restore files
Microsoft Windows includes a feature called Volume Snapshot Service (VSS) for creating backup copies of files, known as shadow copies. These shadow copies get created automatically at set intervals, or before major system changes like software installations. They provide a way to restore older versions of files and folders.
Some ransomware strains delete or disable VSS shadow copies to prevent recovering files. But often shadow copies remain intact after an attack. Using the free VSS recovery software Shadow Explorer, victims can browse shadow copies and restore chosen files to a ransomware-free system drive. This method retrieves files and versions from a period before encryption.
The challenge is ransomware often alters or destroys shadow copies as part of the encryption process to block this method. So it is not a universal solution. But in cases where VSS was left enabled, exploring shadow copies offers another potential back door to recover files for free.
Strengths
- Recovers file versions and deletions using existing Windows feature
- Allows restoring individual files from before infection
- Shadow Explorer provides easy access to shadow copies
Limitations
- Many ransomware strains disable or delete shadow copies
- Only restores files changed since last backup
- Does not work if VSS was disabled before attack
Limiting ransomware impact with filesystem permissions
Adjusting permissions on critical files and folders can prevent some ransomware strains from encrypting them. The basic approach is limiting write access to important locations only to designated user accounts needing it. Ransomware running under broader permissions is then blocked from changing protected files.
For example, revoke write access from general user accounts for system files and folders. Also, hide backups and shared directories from unauthorized users. Configure any accounts with backup duties to have minimal rights to other locations. These steps compartmentalize access and reduce possible damage if ransomware infects a system.
While helpful, ransomware using administrator privileges still gains full reign over permissions and encryption. So view this method as another layer of defense, rather than a complete solution for blocking attacks.
Strengths
- Limits ransomware’s ability to encrypt files
- Compartmentalizes access to minimize corruption
- Helps protect critical system files and backups
Limitations
- Administrator accounts still have full access
- Requires careful planning and user training
- Does not work on all files if limited user infected
Using tools to recover deleted files
Some ransomware adds insult to injury by deleting files after encryption. This removes any remaining fragments left behind after the encryption process. However, tools exist that can restore deleted files in some cases by scanning for file signatures left on the hard drive.
Recovery software like Recuva, Disk Drill, and EaseUS Data Recovery Wizard excel at resurrecting deleted files. They can potentially recover files held for ransom if they were deleted rather than fully encrypted. This method is less reliable than others, but provides one last option if ransomware deleted files post-encryption.
Strengths
- Recovers files potentially missed by encryption process
- Restores access to deleted documents, media, and more
- Free recovery tools with deep scanning available
Limitations
- Less reliable for retrieving encrypted files
- Overwritten files may be unrecoverable
- Does not repair damage of encryption process itself
Using free forensic analysis tools
Advanced cyber forensics tools provide another option for analyzing and potentially recovering files after a ransomware attack. Open source tools like Autopsy and Disk Investigator provide capabilities similar to paid forensic toolkits. Features like signature-based scanning, keyword searching, and file carving allow deep examination of storage drives unaffected by ransomware.
Forensic analysis can help reconstruct portions of data and identify files accessible through other recovery methods. It provides low-level inspection difficult for most users to achieve otherwise. Training is required to leverage forensic software fully. But the availability of free, powerful options makes it worth considering for companies or advanced individuals.
Strengths
- Powerful data recovery capabilities rivaling paid tools
- Allows low-level inspection of storage drives
- File signature scanning can identify recoverable files
Limitations
- Requires training to utilize fully
- Does not inherently decrypt files
- Unlikely to recover strongly encrypted data
Preventing and recovering from ransomware attacks
While many free tools and strategies exist for responding to ransomware, prevention should be the priority. A multi-layered security approach combining best practices greatly reduces the risk of ransomware and other malware infections. Consider the following prevention guidelines:
- Keep all software up-to-date with the latest security patches
- Exercise caution with emails, links and attachments
- Install a reputable antivirus program and scan regularly
- Enable firewalls on devices and networks
- Create regular backups of critical data on disconnected drives
- Know what is on your network and be wary of unauthorized devices
Additionally, implementing robust email security, endpoint protection, and advanced malware tools improves antivirus and firewalls’ native defenses. Take time to educate all employees on ransomware risks and prevention strategies relevant to their roles.
With strong prevention measures in place, the free options outlined here provide hope for recovering from ransomware attacks without paying ransoms. Being prepared with reliable backups and response plans gives victims the tools needed to mitigate damage and regain control after an infection.
Conclusion
Ransomware remains a serious threat, with new variants continually emerging. While free decryption tools exist in some cases, they often provide limited capability against newer strains. Instead, the best approach is denying ransomware the opportunity to encrypt files in the first place through comprehensive security and offline backups. With diligence, many files can be recovered from cloud storage, shadows copies, deleted file tools, and drive forensics after an attack. However, preventing ransomware from gaining access and spreading provides the most reliable and cost-effective protection.
