The same fault found last December in KeepKey’s cold wallets was identified. A voltage attack allowed researchers to extract the encrypted seed in 15 minutes.

As part of their research work, the Kraken Security Labs team detected that Trezor’s cold wallets (Trezor One and Trezor Model T) suffers the same vulnerability that was recently identified in KeepKey’s wallets, which allows an attacker to find the way to extract seeds (private keys) just by having physical access to the wallet for approximately 15 minutes.

During that period, the analysts were able to conduct a voltage failure or voltage glitching attack through which they managed to extract the encrypted seed. This type of attack involves manipulating hardware variables to cause temporary problems in secure devices, which manipulate or retain confidential data.

The researchers add that this procedure takes advantage of the inherent faults in the microcontroller used in the wallets. They explain that it is difficult for the Trezor team to do something regarding this vulnerability without redesigning the hardware, which they also concluded when they evaluated KeepKey’s cold wallets last December.

At that time, they determined that the vulnerability stems from the manufacturer’s firmware, which is the computer program that establishes the logic controlling electronic circuits. The voltage failure attack is aimed at the memory of the microcontrollers that are executed at device startup, point at which the security settings of the chip are loaded.

Regarding Trezor’s wallets, the analysts indicate that the extraction of seeds is not a new territory. They remember that Trezor has implemented measures against a variety of previous hardware attacks, including successful mitigations against glitching attacks. However, analysts say that the test that they have just run could counter these mitigations.

Trezor Responds

Before the publication of Kraken Security Labs, the Trezor team (SatoshiLabs) identifies the vulnerability and even recommends that users read the material to know in detail how the attacks work. They even add an explanation of what is known as downgrade attacks, to which Trezor’s wallets are also vulnerable. These are aimed at the hardware vulnerability of the STM32 microchips used in the Trezor One and Trezor Model T models.

Given this situation, their response emphasizes that these attacks require physical access to the device to manipulate it, so users’ role in protecting their wallet is highlighted.

They add that although only about 6% of cryptocurrency users are concerned about physical attacks, they treat physical vulnerabilities as urgently as any remote vulnerability. In consequence, they recommend implementing the “passphrase” function, an additional password phrase that is not stored anywhere in the hardware.

Users Question Response

Concerning this argument, Twitter follower @mvidallopez developed a thread through which he questioned Trezor’s position. He said that he saw a lot of complacency with Trezor’s response about the vulnerability that Kraken had revealed, adding that it should be more demanding.

To conclude, he says that in 2020 it is not acceptable to sell cold wallets with hardware that has long been known to be vulnerable, due to its design. He also disagrees with transferring the mitigation of the problem to the customer. In this regard, it should be remembered that using the additional phrase requires an additional “passphrase” configuration, with which novices risk losing their funds.

By Alexander Salazar


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