FIPS-certified USB drives have security flaws

The recently reported discovery of a vulnerability in supposedly secure USB flash drives has prompted a review of the certification process for cryptographic modules under the Federal Information Processing Standards. The flaw could potentially allow unauthorized access to encrypted data

At least three USB drive models subject to the vulnerability discovered by the German security firm SySS had received the FIPS 140-2 certification, a requirement for government encryption tools administered in this country by the National Institute of Standards and Technology.

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“We are in the process of reviewing the information on this vulnerability,” NIST officials said in a statement issued Friday. “From our initial analysis, it appears that the software authorizing decryption, rather than the cryptographic module certified by NIST, is the source of this vulnerability. Nevertheless, we are actively investigating whether any changes in the NIST certification process should be made in light of this issue.”

Affected FIPS certified devices include the SanDisk Cruzer Enterprise FIPS Editions CZ32 and CZ46 in 1G, 2G, 4G and 8G; and the Verbatim Corporate Secure FIPS Edition in 1G, 2G, 4G and 8G. A number of other USB drive models from SanDisk, Verbatim and Kingston not certified under FIPS also are affected by the vulnerabilities.

All three companies have issued software updates to correct the problem.

The vulnerability was reported in December by SySS, where researchers also created a tool to exploit it. The drives use the AES encryption algorithm with a strong 256-bit key to encrypt data stored on the devices. The AES algorithm remains secure, but the problem lies in the application running on the host computer to validate the password used to authorize decryption of data. Researchers found that the program sends the same character string to the drive to authorize decryption when the proper password is used. By inserting a tool in the password entry program to ensure that it always sends that authorization string, regardless of the password entered, users can decrypt data without using the proper password.

To date, FIPS certificates for the affected USB drives have not been revoked.

The FIPS Cryptographic Module Validation Program is a joint effort of NIST and the Communications Security Establishment of Canada to ensure that cryptographic tools meet government standards for performance and security. The most recent cryptographic standard, FIPS 140-2, was released in 2001. Testing is done by independent labs accredited by NIST, and the FIPS validation is required in cases where encryption of data is required.