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Signal Blocking

Signal blocking is a physical security control used to prevent unauthorized wireless data exfiltration and protect equipment from damaging electromagnetic events. Faraday cages and boxes are common implementations that block radio frequencies across a range of threat scenarios.

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About this video

Signal blocking addresses a specific physical security risk: an attacker who gains access to a network may attempt to exfiltrate data wirelessly rather than over a wired connection, bypassing many traditional monitoring controls. By blocking radio frequency signals within a defined space, organizations can prevent unauthorized wireless transmission of data, covering protocols such as Wi-Fi and RFID. This control can be applied selectively to certain frequency ranges or broadly across all wireless bands depending on the security requirements of the environment. A Faraday cage or Faraday box is a well-established implementation of signal blocking. These enclosures are constructed to prevent electromagnetic signals from passing through their walls in either direction. In a security context, they can house sensitive storage media or equipment to prevent remote access or signal interception. They also serve a protective function against high-intensity electromagnetic events, such as an electromagnetic pulse or a strong solar flare, both of which can damage or destroy unshielded electronic equipment. The level of protection a Faraday enclosure provides scales with its construction, so the appropriate solution depends on the strength of the electromagnetic threat being mitigated.

What you'll learn

Explain the purpose of signal blocking technologies, including Faraday cages, in preventing unauthorized wireless data exfiltration and protecting equipment from damaging radio frequency events.

What's covered

Signal Blocking

Why Block Signals
- Prevent Data Exfiltration
- Protect Sensitive Equipment
Types of Signals Blocked
- Radio Frequency (RFID)
- Wi-Fi Signals
- EMP and Solar Flares
How Signals Travel
- Waves Through the Air
- Data Embedded on Waves
Faraday Box / Cage
- Blocks Strong RF Signals
- Protects Stored Drives
- Guards Against EMP

Key terms

Data Exfiltration: The unauthorized transfer of data from a system to an external destination.
Faraday Cage: A shielded enclosure made of conductive material that blocks electromagnetic signals, used to protect equipment from damaging radio frequency events and prevent wireless data exfiltration.
Radio Frequency Identification: Radio Frequency Identification uses electromagnetic fields to automatically identify and track tags attached to objects or embedded in access cards; in physical security, RFID cloning and eavesdropping attacks can allow unauthorized facility access.
Electromagnetic Pulse: An Electromagnetic Pulse is a burst of electromagnetic energy that can damage or destroy electronic systems and infrastructure, representing a physical security threat from natural events such as solar flares or deliberate high-altitude nuclear detonations.

Topics

Signal Blocking Faraday Cage Physical Security Radio Frequency Wireless Security Data Exfiltration

Transcript

Another thing we may want to implement is signal blocking. For instance, maybe somebody plugs something into our network and then they use wireless to do data exfiltration. They're grabbing data from our network and then they're stealing that data, and it's going through a wireless signal. So we might want to consider some sort of signal blocking.

Blocking ranges

Waves go through the air, and what we can do is embed a signal on a wave and send it through the air, so that way we can communicate and send data. We might not always want that data to be sent, though. So that's where we might want to take certain ranges and block the signal of certain ranges, or maybe all ranges. When we talk about things like radio frequency identification, or when we're talking about things like Wi-Fi, there are times when we want to block those signals.

Faraday boxes and cages

Another example of this is a Faraday box or a Faraday cage. This is a Faraday box right here, and what it essentially does is block signals. It's designed to block stronger signals, because some of these signals can be so intense they can damage equipment. So I could put in a drive right here, so that way if there is some sort of strong radio frequency, I can block the signal and have it not damage my equipment.

Typically that doesn't happen, but where there is concern that would really come into play is maybe something like an EMP going off, or a flare from the sun, a solar flare. Those can actually knock out some equipment. So if I put it in here, it could do an element of protection. Although I don't know that this is big enough or strong enough to be able to protect against a really strong solar flare, that's what this is designed for. A Faraday box is designed to protect from those signals in the air.

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