Anti-Hack Access Card Shields Tested
Keeping your access control card information secure is becoming a big priority, especially since cheaper copiers can hack details easily. Multiple products claim they can keep those RFID details hidden, so we bought several examples to put them to the test, including:
- RFID Blocking 'Security Wallet'
- Paper and Foil Card Sleeves
- FIPS 201 Metal Shield Card Holder
- Standard-duty Aluminum Foil
We tested four common RFID shielding products to see which one performed the best, with a surprising result. Catch our test and demo video inside.
Key Test Findings
Our testing yielded the following insights about card shields:
- The paper/foil card sleeves were the most effective shields of the products we tested.
- Shielding the entire card is important. Only partially obscuring the card may still allow the card to be energized and transmit data.
- 125 kHz cards are more difficult to shield than 13.56 MHz. The higher frequency signal has a harder time passing through line-of-sight obstructions, but that same property also makes shielding more effective.
- For many shield products, they may intermittently or even generally block scans, but successful scans can still be periodically achieved.
- Read range of the copier/reader impacts shield effectiveness strength. Higher output power/longer range readers can defeat and pass-through shielding methods that may be effective for smaller readers.
In the video and sections below, we examine these findings in detail.
RFID Shielding Demo Video
In the video below, we walk through the four types of shields we tested, with the surprising most effective solution being the paper/foil sleeves:
FIPS-201 Rated Card Holder Shield - ~$30 each
In terms of product claims, the shield claiming the most sophisticated performance was this FIPS-201 Compliant Card Holder that claims the product "protects your card from unauthorized scanning."
Our test shows this claim is only partially true. Scans did not happen when the side of the holder covered by the integral metal shield was presented to the reader, but if the 'open' unprotected face of the card faced the reader, scans happened normally, if not requiring a closer presentation distance, the majority of the time. The shield stopped only 10% of the reads in this configuration, versus 100% when reversed.
Because access cards are commonly used as picture ID badges, they most commonly will be worn with the exposed, vulnerable side facing out. This makes the true value of this holder as an access credential shield dubious.
Paper/Foil Sleeves - ~$2 each
Our test turned a surprising result - one of the least expensive and 'flimsy' products performed the best. These ~$2 foil-lined paper sleeves were very effective at stopping scans cold.
In terms of performance, the sleeves stopped scans from readers and our test card copier 100% of attempts for both 125 kHz and 13.56 MHz cards. In general, the sleeves completely covered surfaces of the card, which means a rouge source has little penetration area to energize the card internals.
Of note, our test used a new, undamaged, unripped sleeve, but the lightweight paper construction is not likely to hold up well after even days of routine use.
Anti Hacking Wallet - ~$15
The 'fashion conscience' method of a purpose specified 'Security Wallet' did not meet performance claims either. While the product claims "When your wallet is closed built in RFID-Blocking Technology prevents reader device signals from penetrating", our testing shows that scanning 125 kHz cards with the wallet closed was typical when the thinner side faced the reader.
Typically, the wallet blocked scans when the thicker/more bulky side faced the reader and copier, but intermittent scans still occurred.
One important note - 13.56 MHz scanning of any sort in any wallet configuration was blocked, and the wallet was successful.
Aluminum Foil - ~$2 per foot
Some may wonder why the need to buy shielding solutions, when common household materials can be used more cheaply? We tested common consumer-grade standard duty aluminum foil, with a sheet thickness of about 0.6 mils thick. In our test, anything less than 5 plys (folded layers) of foil was not an effective shield. It took a full 6 plys before shielding was sufficient enough to block 100% of attempted scans.
In terms of durability, raw foil was the worst option and tore easily, making its deployed use a temporary method at best.
Migration Away From 125 kHz Still Prudent
As noted in our Hackable 125kHz Access Control Migration Guide, the risk in copying credentials is worst in unencrypted, open air 125 kHz cards. We noted:
"For many years, the <scanning> risk was perceived as too minor to warrant spending money, however, the emergence of cheap easy copiers has changed and amplified the risks. Security managers should now consider the difficulty of getting unauthorized duplicates for 'high tech' 125 kHz cards as easy as getting 'low tech' duplicate mechanical keys cut at any hardware or big box retail store."
For those credentials, card shielding can play an important part in making copying difficult, especially given the 'absolute' method of moving to 13.56 MHz cards is costly. Of our tested options, the most effective shields were among the cheapest, and far less to employ than updating cards and readers.
However, the durability of sleeves as a permanent fix is dubious. While using a paper sleeve to shield cards is inexpensive, they will not likely hold up under constant use, and frequent replacement should be expected.