Recognize Fake USB Flash Drives and Memory Cards: Tips Against Fraud

In the net there are not only good offers in terms of USB sticks and (micro) SD cards. Sometimes flash memory media are offered with false promises, some supposed bargain turns out to be a jerk. But if you are a little familiar with the subject, many fraudulent offers before buying. And anyone who already owns suspicious storage media can easily check it, namely with the Windows tool "H2testw" (download here).

Easily debunked are counterfeits with much too high capacity : A MicroSD card with 1 TB is so far simply not, as little as an SD card with more than 1 TB and a USB stick with more than 2 TB. There are simple technical reasons for this.

MicroSD cards with 512 GB are currently a technical masterpiece: at just 1 mm in height, 17 bare silicon chips are stacked on top of each other, namely 16 NAND flash chips with 32 GB each and a controller chip. The latter connects the NAND Flashes with the SD interface.

Swissbit / "c't"

Inside a microSD card, up to 16 flash chips are stacked on top of each other (the controller is on the right).

All chips come from "thinned", so abraded silicon wafers, so that the chip stack remains below 1 millimeter. No chip may also have more footprint than about 1 square centimeter - a MicroSD card is not even bigger. Only with the next structural reduction of the flash chips are higher capacities expected again.

Because there are only about five companies worldwide that can produce such sophisticated flash chips, surprises are highly unlikely. Hardly to be expected is that a hitherto completely unknown manufacturer trumps the established Flash brands (see table) in manufacturing technology. The latter compete for maximum capacity, because they bring more profit and much attention.

Flash storage media: Large manufacturers

other manufacturers of NAND flash chips: SK Hynix, Intel / Micron, Yangtze Memory (YMTC)

In other words, who can actually make a USB flash drive with 2 TB, will not sell it for 30 euros, if he can get 300 euros for it.

Far too low prices are suspicious even at lower capacities. As indicated, there are only a few manufacturers of the actual flash chips and their prices are approximately known. Extremely low prices indicate counterfeits that have far less flash memory than they claim. It is then simply manipulated the firmware of the controller: It reports a higher capacity to the operating system. This inevitably results in data loss beyond a certain amount of actual written data.

With an online price comparison service, you can find out in minutes what a (micro-) SD card or a USB stick with a certain capacity costs at least: Look at the prices of the brands mentioned here. A MicroSD card with, for example, 256 GB is currently hardly get under 24 €.

It is also suspicious if a storage medium externally mimics the product of a well-known brand . Reputable manufacturers are keen to establish their own brands. Also typos in the product name or on the packaging as well as strange formulations indicate forgeries.

Also typical for "Fake Flash" are specifications that deviate from the requirements of the SD Association . This determines, for example, that cards with 64 GB or more should carry the designation (Micro) SDXC, ie not SDHC or SD, and must be preformatted with exFAT. A 64GB card with "microSDHC" lettering and FAT32 is weird.

A weak indication for mischiefs are lack of information about speed , because unfortunately they also like to omit established companies. A map with the logo for "Class 10" must be able to be written sequentially with at least 10 MByte / s. Cards with UHS-I or UHS-II interface of class U3 must provide 30 MByte / s. This can easily be checked with Windows tools such as Crystal Disk Mark - and you should complain about a far too slow card.

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This fake SD card mimics the look of a SanDisk Extreme Pro - even though the name "Kimsnot" is tiny.

Speaking of speed: Flash media where the merchant does not specify the data transfer rate often read and write toothless at less than 10 MB / s. This limits the practical usability.

Flash memory is so cheap that you should not buy the cheapest, but brisk branded goods. For SD and MicroSD cards it should be at least 30 MB / s. USB 2.0 sticks are simply no longer up-to-date and most products still sold are well below the 35 to 40 MByte / s that are possible with USB 2.0 HighSpeed. Take sticks only with USB 3.0 and at least 50 MB / s.

Flash storage media: maximum capacity

1 sometimes also called "TF" for the outdated name TransFlash

As of September 2018

It's not that easy to expose good counterfeit media with common capacity, such as supposed 128- and 256-GB cards with actually only 8, 16 or 32 GB of flash memory. Unfortunately, you will not find this out until after the purchase, under Windows with "H2testw": The test software of our former colleague Harald Bögeholz describes the entire storage medium with test data and then reads it out again.

This works only with a formatted, but empty medium and can take a long time - lame writing with only a few megabytes per second is as mentioned an indication of counterfeiting. The complete test cycle can run for two to three days on a 1 TB medium.

Therefore, first of all only test 64 GB (input "64000 MB"), often the first errors occur after less than 8, 16 or 32 GB. If this is the case, delete the test data and start a complete test run. Promotes error again, the storage medium is most likely broken or fake - with the small residual risk that the card reader, the USB socket or the main memory of your computer have defects.

To check this, you can also run "H2testw" again on another computer. Incidentally, you do not have to install the software: Unpack the downloaded ZIP file in any directory and then double-click h2testw.exe.

"H2testw" also indicates how fast it is currently reading or reading the storage medium. Although "H2testw" is not intended as a speed test, the values ​​give a rough guide. For Linux there is the test software F3.

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For storage media with a fake capacity indication, "H2testw" will alert, but the test of 1 TB may take several days.

There are product counterfeits that fail to "H2testw" or F3: storage media with inferior, but functional flash chips that sell scammers under false brand. Such a product works normally, but may be earlier than the original. Such counterfeits are recognized only by experts - and therefore it is hard to protect yourself from it.

In the established specialist trade, however, the risk of counterfeiting is lower than with unknown (online) providers. But also flash memory from trusted sources should be carefully tested before the first use, such as "H2testw": This prevents data loss.