Improved Canned Air Attacks Against REX Sensors

Bypassing Request-to-Exit (REX) sensors with canned air and other mediums isn’t a new attack, and is widely used as a covert method of entry. However, there are times where this attack could be possible, but certain elements such as a small physical gap that the straw can’t fit through, REX sensor being farther away, etc., prevent it from working.

The standard straw that comes with cans of compressed air certainly has its limits as it has a larger profile, isn’t flexible, and is shorter in length. This can cause issues if the group under the door isn’t flat, or there isn’t much of a physical gap. Even pushing the straw in through a corner of the door frame can sometimes not get you close enough, or directed enough to trip the sensor.

Recently I discovered a 50″ aerosol can replacement straw from “Flexstraw”. Although it says that it’s not to be used for micro-dusters, I decided to give it a try anyway, and I’m SO glad that I did!


Although the smaller diameter of the straw restricts the flow of the compressed are quite a bit, it’s still a wide enough opening that allows it to be effective. Not only is straw very flexible, but its smaller profile allows me to slide this through areas where the standard straw will not fit. And the best part is that it’s much longer!

I recently tested this out during an assessment. The bottom of the door was closed off with a proper threshold, and metal stripping, not allowing anything through. However, I was able to slide this straw through a very small opening on the bottom, right corner of the door frame, a place where the standard straw would not fit. The REX sensor was farther away, but that was not an issue as I just put the straw in farther, until the compressed air was close enough to work its magic.

This is now a regular in my physical toolkit bag, and I highly recommend it!



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