A Look at the 5 Most Common Types of Cyberattacks

Learn more about the key threat vectors you will need to combat with vulnerability assessment tools and cybersecurity best practices.

The modern cybersecurity landscape is incredibly complex by any standard. Whether or not you are a cybersecurity professional, everyone can benefit from learning about the dangers you're most likely to face — and determine how security tactics like vulnerability assessment can help protect you. 

Sizing up the most common cyberthreats 

The damage done by common cyberattacks is often measured in loss of personally identifiable information and other valuable data. According to the Identity Theft Resource Center (ITRC), the vast majority of data breaches in the U.S. during 2019 — 1,115 out of 1,473 — stemmed from hacking, intrusion or unauthorized access, exposing more than 157 million sensitive records.¹ That said, the loss of PII is just one adverse consequence of an attack. There's also the interruption of business to consider, as well as damage to the network and IT infrastructure — both of which can seriously hurt your organization's financial bottom line.

The hacks noted above were the product of numerous threat vectors; some fairly common, others obscure. While it can't hurt to know them all, it's much more urgent that you know five of the most common cyberattack types² and what they entail: 

• Malware: This catch-all term encompasses a number of different cybersecurity threats, including everything from viruses and worms to banking trojans, adware, spyware and ransomware. Once these programs gain access to a targeted system, they can steal, destroy, encrypt or corrupt valuable databases, files and applications. 

• Phishing/social engineering: We've all received emails that might look normal at first but have one or more suspicious details, urging us to click on a URL or download a file. Often used to steal login details and the confidential info those credentials protect, phishing scams are also used as delivery systems for malware or other exploits, and they can be deployed via email, phone or SMS.

• Man-in-the-middle attacks (MitM): These entail intrusions upon two-party transactions — e.g., between an individual and their bank — intended to steal data shared between the two. MITM attacks may be especially dangerous for organizations that have employees who work remotely on public Wi-Fi (at a coffee shop or library), as they can only be carried out over unsecured networks or if one party's device is already compromised. 

• Denial of service (DoS): Hackers overwhelm servers or networks with frivolous traffic to render IT infrastructure useless in denial-of-service attacks, often to force the victim to pay a ransom. DoS campaigns can originate from one computer and internet connection or many; the latter are distributed DoS attacks, often coordinated by botnets.³ Botnet-driven DoS attacks can simultaneously cripple dozens of organizations across multiple continents, as seen in the infamous Mirai and WannaCry attacks. 
  
  
• Structured Query Language injection: SQL remains the most common method by which essential communications in a relational database occur.⁴ The injection of malicious code puts a database at the mercy of an unauthorized user, who can then steal any business-critical information within it.

Aside from those above, there are certainly other cyberattack types worth worrying about: rootkits that are subtly implanted to steal or corrupt data, formjacking of payment details,⁵ cross-site scripting (a cousin to SQL injection) and more. But the five bulleted exploit classes should absolutely be at the top of any organization's threat list. Additionally, new threats are always emerging, so another group of attack types could become more common in the not-too-distant future.

Evaluating cyberthreats by industry (and risk level)

Healthcare and finance appear to face the most danger from malicious online actors, albeit in different ways. According to the ITRC, healthcare organizations experienced 525 breaches during 2019, but didn't see significant loss of PII — likely because attackers were more interested in disrupting operations to elicit ransom payments. Banking and finance had the fourth-fewest breach incidents (108), but saw almost 101 million sensitive records exposed, far more than any other sector. 

Different sectors are also more at risk of certain attack types. Ransomware attackers have been laser-focused on healthcare organizations due to the wealth of data in their systems. Such attacks rose by 350% in that last quarter of 2019.⁶ As such, a hospital would do well to focus on phishing-based ransomware deployment. 

For similar reasons, state and local governments find themselves targeted with ransomware almost as often, as high-profile incidents throughout 2019 in Florida, Maryland, Georgia and Texas demonstrate.⁷ (Texas saw 23 municipalities simultaneously ransomed.⁸)

In terms of specific threats, a bank, for example, should probably be most concerned about the various classes of ATM malware (two dozen or more⁹).

It's also important to consider which attack types do the most damage, regardless of industry. Any self-propagating attack, such as the Emotet banking trojan, is extremely dangerous because of how it actively resists efforts to eradicate it. The botnets that have succeeded Mirai, meanwhile, are extremely dangerous because of how fast they spread among IoT-connected devices.

Options for protection

It's critical to protect yourself from all cyberthreats, even those that may not threaten your organization as directly as others. Even a DoS attack that halts operations for a brief time (even as little as 15 or 20 minutes) can substantially hurt an organization, especially a small- or medium-sized business.

You must leverage strong cybersecurity measures, including penetration testing and threat modeling. These can determine exactly where your organization's weak spots are, the specific urgency of these weaknesses and how attacks might play out in real time. Using such tactics within a comprehensive, continuous vulnerability assessment program is critical to your chances of success, especially considering that vulnerabilities can be broadly exploitable if they're known to attackers for barely a day or more.

Start discovering your vulnerabilities today with a free 7-day trial of Nessus Professional. With more than 100 new plugins released each week, Nessus helps provide timely protection from the latest threats.

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_{1. ITRC, "2019 End-of-Year Data Breach Report," January 2020
2. HP, "What Are the Most Common Types of Cyberattacks?," May 2019
3. Webopedia, "DDoS Attack - Distributed Denial of Service"
4. InfoWorld, "What is SQL? The first language of data analysis," November 2019
5. Symantec, "Internet Security Threat Report," February 2019
6. Corvus, "Security Report: Healthcare - Hospitals, Providers and More," February 2020
7. National Law Review, "State And Local Governments Continue To Be Favorite Targets Of Cyberattacks," September 2019
8. CNBC, "Alarm in Texas as 23 towns hit by ‘coordinated’ ransomware attack," August 2019
9. Kaspersky, "Cyberthreats to financial institutions 2019: overview and predictions," November 2018}