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Is your USB thumb-drive genuine OR How to test your USB thumb drive / memory card!

Chetan KhuranaPD Director
Versatile talent, doing things unknown, passionate about technology, OSS, photography, hobby electronics, and taking back control with DIY!
If you are planning on buying a USB drive from eBay or any other popular online e-commerce site, chances are that in spite of those high seller ratings, you may still end up getting a counterfeit!

Popular USB drive makers like Kingston, Transcend and the like are much more likely to be duplicated.

And when the sole usage of your latest thumb drive is going to be that crucial back-up routine, it becomes vastly important that the drive itself is trust-worthy and pristine, lest it ends up as a double whammy!

It becomes even more difficult when the forged units sport nearly 100% original looking packaging. And bar-codes and serial numbers are something too complex for an end user to verify until the same are verifiable online @ the drive maker’s website.

Counterfeiting in USB drives involves hacking of a USB drive’s firmware (basically a low-level editing of the firmware) so that the drive’s specifications report a higher than actual capacity (of the physical NAND chip on board)

As a result, when you try to write data to the drive over and above its actual capacity, your data gets stored as corrupted.

Certain tools for testing out USB blanks are slowly becoming a sure shot, one step verification standard.

These can actually be used both for detecting the bogus USB as well as to check the actual / real world performance (i.e. capacity / operating speed and so on) and other advertised specifications.

The most popular and commonly used application of the lot is the H2testw which is the much proclaimed Gold Standard in Detecting USB Counterfeit Drives. The last documented version is the H2testw 1.4.

NOTE: this application is capable of testing USB thumb-drives as well as SD cards (Mobile/camera based MMC cards) memory cards!

The direct download URLs for the application are –


H2testw 1.4 Usage

1.      Launching the application’s executable leads to the following UI –

H2Testw launch UI
2.      Choose your language as English (or Deutsch if you are German!)

3.      For best results, ensure that the drive to be tested is already backed up and formatted, as the test performed is data destructive. So copy off any data and format the drive already!

4.      Select the target USB – browse and select, here H: is selected –

H2Testw UI Select target USB drive here
5.      Select the option to “Write + verify”. The test will start and a similar window is displayed –

 H2Testw Test in progress
6.      Wait for the test to complete and the results to display. On a large capacity drive, this would take some time. So sit back and let the application do its job ¿
7.      After the completion, a similar looking test result is shown –

a.      Sample Output for an authentic 2 GB Drive (what I tested on my machine)

 H2Testw UI - Valid USB result
The above is a pass message for a valid/authentic drive.

b.      Sample Output for a Fake 64 GB Drive (from the sofakeflash site’s H2testw page (
H2Testw UI - Forged USB result

Evaluating the above FAKE USB’s result, it is clear that a 4GB flash drive is masquerading as a 64 GB flash drive. Imagine the seller’s and the fake USB creator’s audacity!

Moreover, since a genuine 4GB drive should be about 3.9 GB after formatting (and not 3.8 GB), the difference indicates that some sectors are obviously not usable and have been marked as bad. This further indicates a low quality NAND chip.

So once you start using the drive beyond 3.8 GB capacity, the data will surely be unrecoverable.

Help! I actually have a fake drive? Now what?

If your test results indicate a fake USB at your hands, you can approach the seller on eBay (or your e-commerce site) and tell him the situation. Thanks to H2testw 1.4, you have the required proof too to back-up your claims.

Most sellers would be quite forthcoming in helping you get a replacement or a refund. But in case of issues, you can always post comments on the e-commerce site with a copy of this report.

Following which, any self-respecting seller should be willing to help you, as the reputations are what eventually would get them their business.

Hope the above article helps you to keep counterfeit USB's at bay!
Chetan KhuranaPD Director
Versatile talent, doing things unknown, passionate about technology, OSS, photography, hobby electronics, and taking back control with DIY!

Comments (3)

tigermattStaff Platform Engineer
Most Valuable Expert 2011


Very many thanks for this article. This is something I hadn't ever considered to be an issue, but it is a thoroughly interesting topic to read about. I have voted "Yes" above to indicate this was helpful, and I will be sure to file this for future reference!

Mark WillsTopic Advisor
Distinguished Expert 2018

Ditto - what tigermatt said :)

I have accumulated dozens of "random" usb drives and now intend to check them all.
Chetan KhuranaPD Director


You are welcome, guys!

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