Sometimes, the most dangerous attacks aren’t blatant attempts to take you down in one fell swoop. Ironically, the most devastating attacks are those that lie in wait, quietly working in the background until it’s too late for you to do anything about them. These passive attacks are designed to monitor your activity and sometimes steal personal data but never alter your data.

What Is a Passive Attack?

A passive attack is when a malicious third party gains access to a device to observe information exchange without altering it. You can liken a passive attack to an invisible intruder who peeks through your windows and follows you about in your house, learning where you keep your valuables. This invisible intruder will not touch anything but can just as easily pass the information gotten to robbers, who can then act on it.

Passive attacks generally do not interfere with your system’s running, nor do they alter the system’s resources. It is common for passive attacks to be the first step in larger, more active cyberattacks due to their unnoticeable nature.

In a passive attack, what is targeted is the confidentiality of messages or information exchanged. Attackers can observe and extract a copy of the system’s data or messages to be used later for unauthorized purposes.

Alternatively, passive attacks can be used by non-malicious individuals, such as ethical hackers, to pinpoint vulnerabilities to be corrected in a system. This concept is referred to as vulnerability assessment. Other than this, other uses of passive attacks are often malicious.

Passive attacks are the cyber version of surveillance, secretly exploring an area to get information. It can be in the form of either passive or active reconnaissance.

Active Reconnaissance

Active reconnaissance is a form of passive attack where the infiltrator gathers information on the vulnerabilities of a system by interacting with the system directly. This may involve port scanning to find open ports that an external body can prey upon.

Many port scanning, network mapping, and penetration testing applications make active reconnaissance possible. Examples include OpenVAS, Nmap, and Metasploit.

Active reconnaissance communicates directly with a system or network to glean information, leaving trails. Although it is faster and often generates more comprehensive information about a target, the trails left behind make it easier to spot than passive reconnaissance.

Passive Reconnaissance

In passive reconnaissance, an external party can observe a target system’s proceedings and weak spots without interacting directly with the system’s or network’s interface. Imagine the intruder in passive reconnaissance watching the movements in a house by just peeking through the window. If patient enough, the intruder will see quite a bit but can not see everywhere from that position.

Passive reconnaissance is hardly detectable but requires more time to be spent without the promise of comprehensive data collection. If stealth is more important than the amount of information gathered, passive reconnaissance will be preferred over active reconnaissance.

How Does a Passive Attack Work?

A passive attack mainly capitalizes on getting to know the weakest, most exploitable entry points to a target system or network. The goal is to find a suitable vantage point where information being exchanged over that network or system can be observed without anyone noticing. Applications and recon programs are often employed to conduct this data breach.

During the exchange of messages or transmission, a passive attacker can use any of these applications to access information and possibly make copies. The attacker might even intercept or analyze network traffic to get insight into what is being exchanged without interacting with the system.

7 Passive Attacks You Should Worry About

Passive attacks can pop up in different forms, depending on the type of your system, the attacker’s intent, and the sensitivity of the information being exchanged over your network or system.

There are several formats of passive attacks out there, but these are seven you should look out for:

1. Wardriving

Wardriving is driving around to find unprotected wireless local area networks (WLANs) to either access their WiFi or private documents. It is also referred to as access point mapping. Companies that use WLANs can prevent war driving infiltrations by installing wired equivalent privacy (WEP) protocols or investing in a solid firewall.

2. Eavesdropping

Eavesdropping is when a third party listens to and possibly copies or records the messages being exchanged over a network in real-time. A typical example is when passwords to social media accounts are stolen when the user is connected to a public WiFi. Another example is someone at a different location listening in on your call or looking at your messages as they are being exchanged.

Leading social media companies use end-to-end encryption to protect their users’ calls and messages and combat eavesdropping.

3. Spying

Spying, also known as cyber espionage, is similar to eavesdropping; the difference is that it isn’t real-time and often has benefits attached. In spying, the plan is to discover information to have the edge over competitors or for blackmail.

Solid firewalls with several layers of encryption should be able to keep stubborn cyber spies out of your business.

4. Dumpster Diving

Dumpster diving is when someone searches through the discarded paperwork or deleted records of an individual or company system with the hopes of finding sensitive information, such as passwords or log-in details.

5. Packet Sniffing

This is where the attacker installs hardware or software that monitors all data packets sent over a network. The attacker monitors data traffic without interfering in the exchange process.

Encryption works wonders in keeping sniffers out.

6. Footprinting

Footprinting, also known as fingerprinting, is part of active reconnaissance. It involves searching for details concerning a network or system to pinpoint its exploitable points.

Digital footprint includes data trails you leave behind after surfing the web, for instance, your IP address. This information can be used to search for even more details that will expose your network’s weak points.

Encryption, disabling location services, and directory listings on web servers are ways of protecting yourself from an undue footprinting attack.

7. Traffic Analysis

Traffic analysis involves looking over a great deal of exchanged information to determine a communication pattern. This helps the hacker to gather information about the users of that network.

Even when messages are encrypted, the frequency of message exchange can still be monitored. It can be difficult to pinpoint when advanced applications, like Wireshark, are used.

To prevent your online calls from being monitored in a traffic analysis attack, ensure you encrypt your session initiation protocol (SIP) traffic information.

What Is the Difference Between Active and Passive Attacks?

In an active attack, nothing is off-limits. You can be impersonated, have your information altered, have a denial of service implemented, and have a whole host of malicious actions that invariably affect your system directly. Here, the emphasis is not so much on stealth as malignancy, making it more easily detected than a passive attack.

In a passive attack, information gathering without engaging the system is the aim. Passive attacks are harder to spot as a result; they do not alter the system in any way. They are often the forerunners of more significant active attacks, as they expose the vulnerabilities of a network or system to malicious actors.

How to Protect Yourself Against Passive Attacks

Progress in cybersecurity has provided us with several options to ensure that passive attacks are curbed. Here are a few trusted ways to protect yourself from passive attacks:

• Use an intrusion prevention system (IPS): IPS functions by detecting and stopping unauthorized port scans before they can complete and relay the full description of the vulnerabilities of your ports to the invaders.
• Use a form of encryption over sensitive data: Using symmetric or asymmetric encryption can make it a lot harder for any third party trying to gain access to your data. Encryption acts like a locked gate to keep your data and intruders out.
• Invest in a fortified firewall: Firewalls monitor and control the traffic on a network, helping to keep unwanted entities from accessing the network’s resources.
• Keep sensitive information as private as possible: Avoid sharing sensitive information online or inputting your log-in details over a public network.

Don’t Be Passive About Passive Attacks

Passive attacks can be a pain, especially since you usually can’t tell when they are being carried out. Be proactive about your cybersecurity. Don’t be passive about passive—or any other form of—attacks!