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Ransomware Detection: Techniques to Catch an Attack


Cyberattacks have unfortunately become a regular occurrence for any organization with an online presence. Ransomware stands as one of the most dangerous types of attack, able to cripple critical infrastructure and inflict heavy financial damage on businesses both large and small. Preventing these attacks requires not only knowledge of detection techniques, but also an understanding of ransomware itself. This article reviews some common methods for detecting ransomware, understanding patterns that indicate an attack, and implementing controls to mitigate them.

Types of Ransomware

Ransomware is a particularly dangerous member of the malware family. It encrypts and blocks access to systems and data on a network, then demands that the victims pay a ransom to the cybercriminals to restore access. Ransomware has become popular due to its profitability: modern organizations need their systems and data to function, so they are often willing to pay money to get their access back. This makes it a lucrative type of attack for bad actors to perform.
Ransomware has several variants and methods of operating, such as the following:
  • Encrypting: The main type of ransomware is designed to encrypt data on a network. The attacker claims they will provide the decryption key once the victim makes the payment, though there is often no way to guarantee the cybercriminal will uphold their end of the deal. WannaCry and Petya are two of the most infamous examples of encrypting ransomware, but various nation-states have also weaponized encryption to cripple their enemy’s infrastructure during wartime, as in the Russia-Ukraine conflict. 

  • Locker: Similar to encrypting, this variant is designed to lock out users from devices instead of encrypting their data. Like versions of ransomware that only encrypt data, this type of ransomware also makes a payment demand to the victim.

  • Doxware: A variant that works in tandem with the previously mentioned techniques and increases the exposure of the attack. The attacker compromises the network with ransomware, then threatens to release sensitive information to the public unless payment is made, in an effort to coerce the victim into paying the money. 

How Ransomware Enters an Environment

Ransomware typically gains an entry point into an environment by socially engineering users into carrying out an action, such as downloading software or clicking on an attachment. Some of the most common entry vectors are:

  • Phishing emails: Easily the most common ways in which ransomware gains access. Users are tricked into clicking on malicious links or attachments within the email. 

  • Misconfigurations: Security misconfiguration can grant cybercriminals access to an environment, especially in the cloud.

  • Malicious websites: Attackers can often compromise a legitimate website or set up a fake website that silently initiates ransomware downloads in the background if users visit it. 

Once inside, ransomware gains a foothold by exploiting vulnerabilities within the compromised machine. After this, it can linger for a while before finally activating and encrypting sensitive files. By the time the ransomware announces itself and the organization discovers what happened, it is too late. Therefore, it is crucial to prevent and detect ransomware before it can strike.

Common Signs of Ransomware

Ransomware operates in a variety of ways, but there are common indicators that an attack may be taking place, which all organizations should recognize. Here are some examples:

  • Spikes in performance: Unusually high processing or disk usage can indicate an encryption job running in the background. 

  • Unknown file extensions: If files with unknown extensions suddenly start appearing, that can potentially indicate a ransomware attack is in progress, as ransomware often adds specific extensions to files after encrypting them. 

  • Unusual network traffic: Another sign is unusual network traffic resulting from the ransomware communicating with a command-and-control server to receive instructions. 

  • Unexpected New Users: The sudden appearance of new user accounts, especially with administrative privileges, could signal a ransomware attack. Attackers often create new access points to establish control and spread the ransomware throughout the network.

  • Unexpected New Changes: Be alert to unexplained modifications in your network, including changes in SaaS applications, firewalls, and other critical network components. These unexpected alterations could indicate preparatory moves by attackers to undermine security systems before deploying ransomware.

Ransomware Detection Techniques

There are many ways to detect ransomware, but there is no single “silver bullet” that can detect and defeat all types. Instead, it is necessary to implement a defense-in-depth framework with multiple strategies and tools, letting them work together for improved effectiveness. Some of these techniques include the following:

  • Anti-Malware: These use signature and behavioral analytics to detect the most common signs of ransomware before it has a chance to spread. New solutions also include sandboxing, which executes software within an isolated environment to check its behavior. If the new software is ransomware, it can be neutralized before impacting the host system. 

  • Endpoint Detection and Response (EDR): EDR solutions are more advanced than anti-malware and offer an excellent additional layer of security. While some solutions combine the capabilities of the two, they should be considered separately. EDR can provide a more comprehensive insight into endpoints and typically uses machine learning to generate a baseline of regular activity on a system. They also allow security analysts to carry out threat hunting to proactively identify signs of ransomware within a network via dashboards, data signals, advanced search capabilities, etc. 

  • Whitelisting: These solutions are highly effective against ransomware because they prevent any unauthorized software (like ransomware) from running on a system. Whitelists provide better protection than blacklists when dealing with ransomware; because ransomware is always changing and evolving, blacklisting one type of ransomware will still leave a system vulnerable to newer variants. As long as any ransomware is not included in the whitelist, it cannot run and cause damage. Whitelists are also helpful against zero-day attacks that exploit unknown vulnerabilities. 

  • File Integrity Monitoring: These solutions are designed to monitor files and any changes to them in real-time. Ransomware typically tries to rename or modify files, and these solutions can flag if ransomware is trying to do this. 

  • Network Threat Analysis: Ransomware does not work in isolation and often communicates with command-and-control servers to receive instructions from attackers. Detailed network traffic monitoring can highlight these patterns and flag a possible ransomware infection before it has a chance to do damage.

  • Security Monitoring: Besides regular security monitoring alerts, cybersecurity teams can create customized notifications for ransomware attacks. For example, spikes or slowdowns in network performance could indicate that an encryption process is running in the backend.

  • Multi-Factor Authentication (MFA): Implementing MFA is a critical defense against ransomware, particularly in protecting access points. MFA requires users to provide multiple forms of verification before gaining access, significantly reducing the likelihood of unauthorized entry. This extra layer of security ensures that even if login credentials are compromised, the chances of an attacker gaining full access are minimized. MFA is effective in preventing a range of cyber attacks, including those that might lead to ransomware deployment, as it adds a solid barrier to safeguard critical systems and sensitive data.

All these detection techniques mentioned above should be developed as part of a robust defense-in-depth framework. No single layer is foolproof, so they must work hand in hand with other controls such as user awareness, backups, and more.

Antivirus solutions deserve special mention regarding ransomware detection. They might be effective against the regular variety of ransomware, but advanced, sophisticated ransomware can easily bypass signature-based techniques and hide itself with obfuscation. Relying on antivirus alone is inadvisable; instead, it should form part of an overall cohesive strategy supported by other controls, like the ones mentioned previously.

Taking a Proactive Stance Against Ransomware

Data is a critical asset in today’s technology world, and cybercriminals know its value. By cutting off access to this data, they can disrupt businesses and even entire governments, making them submit to ransom demands. By making use of the knowledge and techniques discussed in this article, organizations can implement practical measures to detect ransomware before it causes harm.

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Meet the Author
Mike Dillon is Quest's Chief Technology Officer.
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