Self-encrypting Western Digital hard drives found to be littered with security holes

News by Roi Perez

Western Digital's family of encrypted hard drives My Passport and My Book have come under fire as it was discovered by a team of researchers that some of the drives are littered with security holes.

The vulnerabilities allow anyone with physical access to the drive to easily get access to files stored on the drive to decrypt its contents, even when they're locked down with a long, randomly generated password, the researches claim.

Gumnar Alendal, Christian Kison and ‘modg' released a paper named got HW crypto? On the (in)security of a Self-Encrypting Drive series, which revealed a whole host of security issues.

“After researching the inner workings of some of the numerous models in the My Passport external hard drive series, several serious security vulnerabilities have been discovered, affecting both authentication and confidentiality of user data." said the researchers.

The devices are designed to self-encrypt all stored data, a feature that saves users the time and expense of using full-disk encryption software. The drives all contain a USB bridge that connects the computer to the external drive's SATA interface which then in turn connects to drive itself.

The interface is supposed to be off limits until after the user has entered the correct password, and to prevent cracking and brute-force attacks, the plain-text password is cryptographically salted and subjected to 1,000 iterations of the SHA256 hash function.

However, a sequence of critical errors on Western Digital's part make it possible to crack the password in a short amount of time. The researchers found that it was possible to extract the hash off the drive and load it onto a computer so it could be subjected to off-line cracking.

There were also problems with the underlying password being predictable because the random numbers used to generate it were derived from the current time on the computer clock.

The paper explains “it turns out that these 32 bytes are just eight repetitions of a 4 byte value, reducing the entropy source to a 32-bit value. Even for a truly random 32-bit value, a modern computer needs only a second to brute force [this].”

A backdoor was found where if the default password had only been changed once, the key corresponding to the default password remains stored on the device, making it trivial for adversaries to decrypt it. The flaw can be overcome by resetting the password a second time.

It is clear to see that readers who want to ensure their data is unreadable, should their hard drive be lost or stolen, should continue to rely on full-disk encryption provided by a known software developer.

While there's no guarantee those apps aren't susceptible to their own crippling attacks, they've been on the market longer and have had more time to be subject to the type of testing discussed in this paper.

Meanwhile, Western Digital says it is on the case. Spokeswoman Heather Skinner was reported in The Register as saying: "WD has been in a dialogue with independent security researchers relating to their security observations in certain models of our My Passport hard drives".

"We continue to evaluate the observations. We highly value and encourage this kind of responsible community engagement because it ultimately benefits our customers by making our products better. We encourage all security researchers to responsibly report potential security vulnerabilities or concerns to WD Customer Service and support at"

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