Ransomware is a type of malware that encrypts files on a victim’s computer and demands a ransom payment in order to decrypt the files. As ransomware has become more prevalent, many computer users have turned to encryption as a way to protect their files from being locked and held for ransom. This raises an important question: can ransomware encrypt files that are already encrypted by the user?
What is ransomware?
Ransomware is a form of malware that employs encryption to hold a victim’s information at ransom. It operates by encrypting important files on the victim’s computer system, rendering them inaccessible. The attacker then demands that the victim pay a ransom in order to decrypt the files.
Ransomware attacks have been rapidly growing in frequency over the past several years. Once the victim’s system is infected, the ransomware encrypts files and displays a ransom note demanding payment within a short time limit. If the demanded ransom is not paid, the attacker refuses to decrypt the files, essentially locking the victim out indefinitely.
The ransom demand is usually in the form of cryptocurrency, such as Bitcoin, so that the cybercriminal can more easily receive the payment anonymously. Ransomware is a lucrative endeavor for cybercriminals, who can extort large sums of money from individuals, businesses, hospitals, and government entities.
How does ransomware encrypt files?
Ransomware uses strong encryption algorithms to encrypt files, making them inaccessible to the user. Some common algorithms used by ransomware include:
– AES (Advanced Encryption Standard) – A symmetric encryption algorithm used by many ransomware variants. It utilizes a combination of keys and ciphers to encrypt data.
– RSA – An asymmetric algorithm that uses a public and private key pair for encryption and decryption. The private key is held by the attacker to decrypt files.
– Blowfish – A symmetric block cipher known for its speed and efficiency. Blowfish uses a single key up to 448 bits long.
Once files are encrypted, the only way to get them back is to obtain the decryption key from the attacker. The ransomware encrypts files with the public key, while only the attacker holds the private key necessary for decryption. Even brute forcing the encryption is not practically feasible due to the strength of the algorithms.
What factors affect ransomware’s ability to encrypt files?
There are several factors that determine whether or not ransomware is able to encrypt a target file:
– File type – Most ransomware is designed to encrypt common file types such as documents, images, audio and video. Obscure file formats are more likely to be skipped.
– File size – Extremely large files can sometimes be skipped as encrypting them takes more time and computing resources.
– File location – Ransomware usually targets files stored locally on the machine or on mapped network drives. Files on external storage may be untouched.
– Permissions – Files the user account the ransomware is running under lacks permissions to edit cannot be encrypted.
– Existing encryption – If a file is already encrypted by a different method, ransomware often cannot encrypt it again.
So ransomware does have limitations in its ability to encrypt all files it encounters. However, it will attempt to encrypt any files it can within the parameters of the specific malware variant.
Can ransomware encrypt already encrypted files?
The encryption provided by most ransomware is no match for files that have already been properly encrypted using strong cryptography. When a file is already encrypted with a modern algorithm, the ransomware simply sees a “scrambled” file that it is unable to read or write any further changes to.
However, there are some caveats to this:
– Weak existing encryption – If the existing file encryption uses a weak cipher or improper implementation, the ransomware may be able to brute force, bypass, or otherwise undermine it. Proper encryption using an algorithm like AES is resistant.
– Access to existing keys – If the ransomware is sophisticated enough to detect and obtain existing encryption keys, it could decrypt and re-encrypt files. Proper key storage and management prevents this.
– Hybrid encryption – Some ransomware first encrypts data, then encrypts the encryption keys. So protected files become doubly encrypted.
So the answer depends partially on the strength of existing encryption protecting the files. With properly implemented encryption using a strong algorithm and secure keys, even sophisticated ransomware should not have the capability to add its own layer of encryption on top.
Best practices for protecting files against ransomware
Here are some best practices for using encryption to safeguard important files against ransomware attacks:
– Maintain full disk encryption on your device using BitLocker (Windows) or FileVault (Mac). This protects the entire disk if ransomware tries to encrypt before files are accessed.
– Use file/folder encryption built into your OS for sensitive user data. Windows EFS and Mac Finder-level encryption add protection.
– Utilize encrypted archives for long term storage. Software like 7Zip, WinRAR, and BitLocker To Go allow creating password protected archives.
– Encrypt individual files within Office apps via setting a password. This prevents unauthorized access through Office.
– Consider using third party encryption software that is designed to resist ransomware. Applications like VeraCrypt allow creating encrypted containers.
– Keep encryption keys and passwords stored securely away from the encrypted data, such as on external drive or secure cloud backup.
By proactively encrypting data, individuals and organizations reduce the risk and potential impact of ransomware attacks. Encryption force ransomware to skip over files, leaving them intact.
Can anti-virus or other security measures fully prevent ransomware?
Anti-virus and other security tools provide an important defense against ransomware, but cannot provide an absolute guarantee of preventing infection for several reasons:
– Signature-based detection – Anti-virus relies on updates containing signatures of known ransomware variants. Novel strains go undetected.
– Behavior analysis – Tools that monitor system behavior try to detect encryption of multiple files. Sophisticated ransomware employs evasion tactics.
– Delivery via exploits – Malware often uses software exploits to infect systems in ways that avoid security scanners.
– User errors – Clicking malicious links or enabling macros undermines security tools. Social engineering often tricks users.
– Persistent attacks – Skilled attackers may continuously probe defenses until finding a weakness they can leverage to deliver the payload.
While anti-virus and layered security provide defense in depth against ransomware, individuals should utilize best practices as well:
– Maintain backups offline and immutable to provide recovery without paying ransom.
– Keep software, OS, and security tools patched and updated to close vulnerabilities.
– Exercise caution around links and attachments to avoid infection vectors.
– Use least privilege permissions and limit account access to prevent lateral movement.
With strong security and prudent computing habits, the risk of ransomware can be substantially reduced. But no single solution promises complete immunity from attacks. Taking a layered approach is most effective.
Should you ever pay the ransomware demand?
If you are victimized by a ransomware attack, should you pay the ransom? There are pros and cons to consider when deciding:
Potential benefits of paying:
– Criminals provide the decryption key allowing recovery of files.
– It may be less costly than rebuilding systems and restoring data from backups.
– Paying the ransom quickly can allow resuming business operations.
Potential downsides of paying include:
– There is no guarantee your files will be decrypted, even if you pay.
– It makes you a target for further extortion and attacks.
– Payment funds and incentivizes further cybercrime activity.
– It is unethical to pay criminals, and may be illegal under laws prohibiting material support for extortion.
Many cybersecurity experts caution strongly against paying ransoms. Rewarding criminal behavior fuels further attacks. There are also alternatives to consider:
– Restore encrypted files from clean backups to avoid dealing with attackers.
– Mitigate damage by isolating and rebuilding affected systems.
– Consult law enforcement and cybersecurity pros for threat response.
Paying the ransom should be an absolute last resort. Organizations should have contingency plans that enable restoring data and rebuilding systems without funding adversary’s schemes.
Can ransomware spread onto other computers on a network?
Yes, ransomware absolutely has the capability to spread from an initial infected computer to others on the same network. This allows the ransomware campaign to gain speed and maximize effectiveness.
Some of the techniques ransomware uses to proliferate across a network include:
– Targeting network shares – Mapped drives of other systems are easy targets to encrypt.
– Stealing credentials – Capturing usernames and passwords allows logins to other devices.
– Internal scanning – Probing the LAN to propagate using vulnerabilities.
– Piggybacking on legitimate software – Updating tools or deploying malware masked as installers.
– Lateral movement – Using native OS tools or exploits to move between devices.
– Dropping worms or bots – Payloads that self-replicate from system to system.
To limit ransomware’s ability to spread over a network, organizations should take measures such as:
– Segmenting the network and limiting communication between segments.
– Promptly applying security patches on all systems.
– Scanning for vulnerabilities and closing them.
– Using firewalls to restrict inbound/outbound connections.
– Setting strict permissions on network shares.
– Prohibiting workstations from executing unapproved software.
With strong network security controls in place and robust cyber threat detection capabilities, the spread of ransomware can be contained. But organizations must be vigilant.
Should paying ransomware demands be made illegal?
Some argue that legislation should outright prohibit paying ransoms when victimized by cyberattacks. But there are considerations around outlawing the practice:
Potential benefits of banning ransom payments:
– Removes the incentive for criminals if victims cannot comply.
– Avoids funding illegal activity. Ransoms often money launder.
– Sets a standard that organizations must follow proper security practices rather than take the easy route.
– Encourages investment in security, backups, and resilience planning.
– Provides negotiating leverage, as victims can claim the law prohibits payment.
Downsides and challenges include:
– Difficult to enforce internationally across jurisdictions.
– Hard to stop private citizens or entities from paying covertly.
– Eliminates victim’s options in a difficult situation.
– No help offered to organizations who refuse payment but can’t recover data.
– Unlikely to fully deter attacks, as ransomware can still disrupt operations.
– Legal and ethical issues with overly constraining victims’ actions.
Banning ransom payments has benefits but also faces difficulties in logistics and ethics. More impactful measures likely involve improving baseline cyber defenses, incentivizing cyber insurance, mandating disclosure, and collaborating internationally to apprehend criminals.
Conclusion
Ransomware has proven one of the most vexing cybersecurity issues facing individuals, corporations, and governments today. While research continues into methods for decrypting ransomware affected files without paying criminals, proper preventative encryption remains the most reliable method for safeguarding critical data against compromise. By proactively encrypting important files, folders, disks, and archives, ransomware’s ability to spread and encrypt data can be severely limited. This frustrates the attackers’ objectives while buying time for security teams to detect and respond to the threat.
Encryption is no silver bullet, and organizations still need layered defenses to block initial infection attempts, contain lateral movement, and quickly remediate any endpoints or networks impacted. But paired with comprehensive backups and a sound cyber resilience strategy, strong data encryption provides a last line of defense to protect sensitive information against unauthorized access, including encryption-based attacks like ransomware.