Is the Specter DIY safe? Potential safety risks and how to eliminate them

Specter DIY is a widely used open-source hardware wallet that allows users to securely store their Bitcoin by assembling standard components. But how secure is Specter DIY really? In this post, we'll analyze the Specter DIY's security features in detail and highlight potential vulnerabilities.

Air-gap technology and communication via QR codes

One of the most important security features of the Specter DIY is its air-gap technology. This means the device is not connected to the internet, preventing network attacks. Data flows between the wallet and the blockchain via QR codes. This type of unidirectional communication minimizes the risk of malware being transferred to the device. Since no wired connections are required, the device remains completely isolated.

Weaknesses in QR communication

Although QR codes are considered secure, there is a theoretical risk that malicious software on a device connected to the wallet could generate fake QR codes. A user could unknowingly scan a compromised QR code containing fake transactions or addresses. However, this risk can be mitigated by additional security checks on the Spectre DIY's user interface, which are displayed before transaction confirmation.

Seeding: Random algorithms and user control

Another core feature of Specter DIY is the ability to generate the seed (the 12 or 24 words required to restore a wallet) without trusted random algorithms. This reduces the risk of tampering with malicious random number generators. Touchscreen interactions are automatically used for seed generation, along with a real random number generator. Furthermore, real-life randomness can be transparently incorporated into the seed generation in a playful way.

Firmware security and open development

Because Specter DIY is completely open source, anyone can review the code. This ensures that there are no hidden backdoors or vulnerabilities in the code. A crucial aspect, however, is that users must install the bootloader and firmware themselves, which requires a minimum level of technical expertise. It is recommended to verify the firmware's PGP signatures to ensure that the firmware has not been tampered with.

Attacks on the bootloader and firmware

A potential risk during the initial firmware installation occurs when the bootloader is installed manually. If the PGP signatures are not properly verified, an attacker could install tampered firmware and thus compromise the hardware wallet. Although the probability of this is very low, it can be prevented by verifying the signatures and downloading the official software exclusively from GitHub. Each upgrade completely deletes the old version. To ensure security, always install new, ideally verified, software.

Memory and PIN protection

Specter DIY offers various options for managing seeds and keys. The purest and most secure mode, called "Signing Mode," does not store private keys locally on the device. Therefore, the seed phrase must be manually entered each time it is used.

Alternatively, the confidential data can be stored in the device's flash memory, but this increases the risk of physical theft.

To prevent unauthorized access, the device is protected by a PIN code. An additional security feature ensures that the master key is deleted when the device is locked. Attempting to install modified firmware will also delete the key. The user will be notified by the changing PIN authentication words.

Physical attacks and supply chain attacks

Because Specter DIY is built from off-the-shelf components, this minimizes the risk of supply chain attacks, where malicious hardware could be embedded into the device. Users can purchase the components from trusted sources and assemble the device themselves. This provides a high level of security, as it's impossible to tamper with the hardware without the user's knowledge.

When we ship Specter DIY, we always ship it in a Debasafe security bag, which rules out a supply chain attack.

Attacks on physical memory

If an attacker physically accesses the device, they could attempt to extract the seed or PIN stored on the device. However, this is only possible if the user saves the seed on the device. This is not the case in sign-only mode, as no sensitive data is permanently stored.

Additional security features

We have a whole page with all the security features of the Specter DIY. You can find it here.

Conclusion: Is the Specter DIY safe?

Specter DIY offers a robust security architecture that leverages air-gap technology, QR code communication, and open, verifiable firmware. Attack vectors such as malicious QR codes, improper firmware installations, or physical attacks can be minimized through best security practices. For tech-savvy users who want complete control over their hardware and software, Specter DIY represents one of the most secure options on the market.