How does most ransomware get in?

Ransomware is a form of malicious software that encrypts files on a victim’s computer, preventing access until a ransom is paid. Over the past few years, ransomware has emerged as a lucrative criminal enterprise, with attacks on businesses and organizations skyrocketing. Understanding how ransomware typically infiltrates systems is crucial for defending against this threat.

Email attachments

One of the most common vectors for ransomware infection is malicious email attachments. Cybercriminals send emails with infected Office documents or other files attached, counting on humans’ natural curiosity to get them to open the attachments. Once opened, the malicious attachment installs the ransomware payload on the victim’s computer.

These spam emails are crafted to appear legitimate, often impersonating someone the recipient knows or a company they do business with. The messages try to urgency or importance to get the victim to open the attachment without thinking. Examples include:

  • Fake invoice or receipt attachments
  • “Urgent” requests from the boss or colleague
  • Attachmentdisguised as a shared file
  • Attachment claiming to have important information

Once the user opens the infected attachment, the ransomware is able to compromise the system and begin encrypting files. Email remains one of the most utilized infection methods due to its simple effectiveness.

Infected websites

Another common ransomware infection vector is malicious websites. Cybercriminals inject ransomware code into websites, leveraging vulnerabilities in web applications, plugins, ads, etc. When a user visits the infected site, the ransomware can load itself onto their computer without any action on their part.

Websites compromised in this way often include:

  • Small business websites using outdated software
  • Personal websites and blogs
  • Websites with exploit kits injected into ads or content
  • Hacked plugin repositories

In some cases, users may also be redirected to malicious sites by clicking on malicious ads or links. The ransomware is strategically planted on websites that the attackers know their target victims will visit.

Software vulnerabilities

Hackers are always searching for new vulnerabilities in common software products and operating systems. When they discover a software vulnerability, they can develop exploit code to take advantage of it to deploy malware – like ransomware – onto victims’ computers.

Examples of software often targeted include:

  • Outdated/vulnerable versions of Windows
  • Vulnerabilities in Microsoft Office
  • Unpatched third-party applications
  • Default/weak passwords on Internet of Things (IoT) devices

Keeping software patched and updated is critical to avoid falling victim to attacks on known vulnerabilities. When software vendors issue security updates, installing them right away prevents cybercriminals from being able to use that vulnerability as an infection vector.


Online ads provide another potential vector to inject malware onto users’ computers. Cybercriminals purchase ad space and then deliver their infected ads, known as malvertisements, to unsuspecting users.

When a user loads the malicious ad, the ransomware code hidden within it loads onto their machine. Oftentimes drive-by downloads occur without any action needed on the user’s part. Modern browsers have security measures to try blocking malicious ads, but cybercriminals are constantly evolving their tactics.

Social engineering

One of the hardest infection vectors to combat is social engineering. This relies on manipulating human psychology rather than technical exploits. Cybercriminals trick users into installing ransomware themselves – a highly effective approach.

Examples of social engineering ransomware attacks include:

  • Calls pretending to be tech support, directing victims to install fake “anti-virus” software that is actually ransomware
  • Fake ransomware decryptors that promise to unlock files but actually encrypt them
  • Messages on social media sites, like Facebook Messenger, with links to malware
  • “Tech support” offering to remotely connect to the victim’s computer to fix supposed issues

These techniques rely on scare tactics or appealing promises to exploit human trust and get users to lower their defenses and take actions that compromise their own computers.

Network propagation

Some advanced ransomware strains utilize multiple methods to propagate across networks, amplifying their impact. This includes techniques like:

  • Scanning for open network shares and encrypting files on those drives
  • Stealing credentials to access additional systems and spread laterally
  • Using legitimate system tools and network protocols to copy themselves to more computers

Worm-like behavior enables ransomware like WannaCry and NotPetya to infect entire corporate networks by moving from machine to machine without human interaction. Keeping credentials secure and networks properly segmented helps mitigate this.

Mitigating ransomware infections

While ransomware developers are always innovating new ways to infiltrate systems, the most successful methods often remain the simplest ones that exploit human nature. Training employees to be wary of suspicious emails and websites is extremely valuable. Never opening attachments from unknown senders can prevent many ransomware incidents.

From a technical standpoint, solutions like antivirus software, firewalls, endpoint detection and response platforms (EDRs), and email content filters all provide layers of protection against ransomware infiltration. Keeping software patched and updated is also key. Backing up data regularly enables restoring critical files if ransomware does manage to encrypt them.

Understanding the most prevalent infection vectors highlights the most important areas to focus defenses against ransomware. Layered security and cybersecurity awareness can significantly lower the risk of a ransomware catastrophe.

Infection Vector Description Prevention Tips
Email attachments Malicious files sent as email attachments that infect systems when opened Avoid opening attachments from unknown senders, use email content filtering
Infected websites Websites compromised to exploit vulnerabilities and install ransomware code onto visitors’ computers Exercise caution browsing websites, keep software patched and updated
Software vulnerabilities Exploiting vulnerabilities in operating systems, applications, and services to deploy ransomware Promptly install all software updates, use endpoint protection
Malvertising Injecting ransomware code into online ads to infect site visitors Use ad-blockers and anti-malware tools, avoid suspicious sites
Social engineering Manipulating users into installing fake software or granting remote access Train employees to recognize social engineering tactics
Network propagation Spreading laterally across networks by stealing credentials and exploiting tools Secure credentials and properly segment networks


Ransomware developers employ a wide variety of techniques to infect victims and propagate across systems and networks. While technical solutions are indispensable, training personnel to recognize social engineering and suspicious emails remains one of the best defenses. Understanding the most common infection vectors enables organizations to focus their ransomware prevention efforts for maximum protection.