5 Key Differences Between Active and Passive Attacks

September 6, 2019 • Shannon Flynn


In the modern era, a well-placed cyberattack could destroy a business or even someone’s life. We rely heavily on technology by storing everything from Social Security numbers and banking information to medical histories. A hacker could know as much as they wanted about a person so long as they knew where to look and how to act.

Depending on motives and their instruments, hackers usually go about their business in two different ways: active or passive cyber attacks. While they’re very different, both attacks are intended to complete a similar goal: the theft of information or bringing potential harm to a victim.

Whether this is stealing a competing company’s trade secrets or taking millions of customers’ bank account records, theft of this kind can be devastating.

Active and passive attacks are two different beasts that everyone should know about before feeling confident with their data security. Here are a few differences and some useful information about the two.

1. Active Alters, Passive Observes

An active cyberattack is all about tampering with information or webpages. The goal here is to alter system resources or change the mode of operation. They often create false statements to break coding or modify streams of data to overload systems. Distributed denial-of-service, or “DDoS attacks,” are a form of active cyber attack.

Meanwhile, passive attacks don’t alter anything. Hackers use a form of passive attack when they don’t think they can get through defenses or when they don’t actually want to immediately cause harm.

Passive is all about gathering information. One of the ways a passive attack can occur is if a hacker intercepts messages being sent privately between two people. The hacker can read the contents and gather intel quietly.

2. Active Harms, Passive Waits

Active cyber attacks will always cause harm to the system. Harm is their main purpose and what they’re designed to do. Sometimes, the attack can even be as simple as someone using a fake identity to interact with someone else, the intention being to fool them into trusting the attacker with secrets or even money.

A passive attack, though, doesn’t cause any harm. At least, the harm isn’t caused immediately. Passive hackers allow systems to go about their normal daily routines while simply keeping an eye on operations. Spyware is a prominent example — it can transmit data right from a network or device without the user knowing.

Thus, information lost to the hacker may cause a lot more harm in the future than any active attack could create. Therefore, one attack isn’t always going to be more threatening or intimidating than the other. Businesses and individuals should consider them both prominent threats to monitor and prevent now and for the future.

3. Active Alerts Victims, Passive Remains Silent

When an active attack occurs, the harm is instant. For example, in cases like the aforementioned DDoS attacks, systems will go down immediately, alerting everyone to the problem.

This allows the victims to fix the issue immediately, but it also incites panic and forces quick decisions. Hackers can use these situations to their advantage by demanding ransom after taking information hostage.

Passive attacks intentionally don’t alert victims at all. They hide in the shadows to observe information being handed around and watch how operations are handled from afar.

A passive attack will rarely make itself known unless it turns into an active one. As such, there is no way to combat a passive attack. The only thing an entity can do to protect itself is to use preventive measures like message encryption to ensure hackers can’t review information even if they gather it.

4. Active Compromises, Passive Endangers

When dealing with cybercriminals, the information at-risk is a main difference between active and passive attacks. Active and passive attacks in network security behave differently. An active attack will compromise the integrity of the network and company as well as the availability of information.

On the other hand, passive attacks are considered a threat to confidentiality. These attacks lurk in the background and watch as an individual enters passwords, sends information and processes any form of data. All that information then becomes endangered.

Both can be equally as devastating, though. For instance, identity theft is one of the many types of passive attacks. Cybercriminals wait and steal information without the victim knowing what’s happening. An active attack, like malware, will infect the entire network or computer system to corrupt information.

5. Active Attacks Use Passive Attacks

Though there will always be a fundamental difference between active and passive attacks, they also can work together to create an even stronger attack. This dynamic underlines just how much of a threat the types of passive attacks and active attacks can be.

Active attacks use the information that passive attacks gather. When a passive criminal observes all the information that goes into a system or network, they can then use that to formulate a strong, active attack.

It’s important to note that this trajectory isn’t always the norm — passive and active attacks can operate on their own. In fact, passive attacks don’t need any input from active cybercrime to function. However, if they do team up, the effects can be devastating.

Phishing is a prime example of this team-up. It uses elements of both passive and active attacks by masking itself as an authority figure. Then, if someone clicks on the phishing link or provides private information, the attack then becomes more active as it compromises their identity or finances.

Protecting Yourself

Preventive measures are the only real way to stop attacks from occurring. Once a cyber attack happens, even with security in place, it may be too late to stop the damage from being done.

If you have sensitive information, firewalls and encrypted data is a must for any individual or company. Beyond that, keeping regular backups of all information and destroying sensitive information that’s no longer in use is also a good way to minimize risk.

Then, you’ll need to keep an eye out for phishing scams and attacks. The main signs are any form of authority asking for private information over text or email. If the link, sender address or number or contents look sketchy, it’s best to avoid it altogether.

Anti-virus software and virtual private networks (VPNs) are also key elements for protecting your data. They provide constant security and monitoring, keeping information safe. Then, if an attack does occur, the system should notify you with advice on the proper actions to take.

First Steps Forward

These days, cyberattacks are a case of when, not if, they will happen. Even a small business needs to be prepared for the worst. These five differences help you prepare for active and passive attacks in network security. You now know what to look for and how to prevent such catastrophic consequences.

As for taking those first steps, thankfully, keeping extra hard drives, backing up to a second location like the cloud and being vigilant about the information you keep are the best actions, especially if it means less damage later on. Then, you’re ready for anything.