BSV Multi-Sig Exploited

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Bitcoin Association

As a separate token, BSV developers went a different path with their multi-signature implementation, and due in part to the controversy surrounding the token, struggled to find professional reviews of their approach. Due to multiple blunders, they ended up with a setup which allowed multi-sig withdrawals without any private keys at all, and multiple BSV multi-sig wallets were drained.

This is a global/international case not involving a specific country.

About Bitcoin Association

"One of these features, the so-called pay-to-script hash (P2SH) function, allows a user to send a transaction by signing it to a “script” rather than a public key address. These scripts create special conditions that must be met in order to access the bitcoins sent to them, and they are most often used in multisignature transactions – or, transactions that require more than one party to approve.

Before P2SH transactions came to Bitcoin in 2012, Bitcoin’s only transaction type would send payments to a public key address through the pay-to-public-key-hash (P2PKH) function."

"Bitcoin Core developer and former Blockstream CTO Gregory Maxwell posted on Reddit’s r/bsv that BSV developers removed the P2SH feature some time ago from the BSV blockchain’s code. In the ElectrumSV wallet (“and presumably elsewhere,” Maxwell says in the post), developers replaced the feature with a bootleg, BSV-specific version called “accumulator multisig” that utilized P2PKH transactions instead."

"According to Maxwell, the code’s architects only checked to see if the multisig transactions would work with the exact number of private keys needed to send the transaction (a multisig wallet requires more than one private key to authorize a transaction). They did not test transactions if more or fewer keys than necessary are present."

"In his testing, Maxwell found two significant problems: first, that multisig spends fail if more than the minimum number of keys sign a transaction. Second, anyone could tap the multisig funds “with too few signatures (such as none at all).”"

"One BSV user, Aaron Zhou, lost 600 BSV to an attack exploiting this weakness on his multisignature wallet. When enquiring about the loss to a developer in a BSV chatroom, Zhou said that he trusted “it was safe enough” because “it was introduced by CoinGeek,” a pro-BSV media outlet bankrolled by Calvin Ayre, a close friend of BSV creator Craig Wright. By way of response, a developer in the chat chastised Zhou by saying he should only have committed “small amounts” to the wallet."

"The fiasco is a reminder that cryptocurrency development comes with trade-offs and requires diligence. BSV’s founders and proponents have marketed it as payments-focused coin with massive block sizes and blisteringly fast transaction times. To achieve these properties, BSV developers chose to strip Bitcoin’s code of key features. As evidenced by the multisig fiasco, this can come at the expense of security."

“Kinda makes you wonder what amazing bugs are lurking in their node software or wallets. I can say for sure: I'm not going to run any of it and risk finding out.”

This is a global/international case not involving a specific country.

The background of the exchange platform, service, or individuals involved, as it would have been seen or understood at the time of the events.

Include:

• Known history of when and how the service was started.
• What problems does the company or service claim to solve?
• What marketing materials were used by the firm or business?
• Audits performed, and excerpts that may have been included.
• Business registration documents shown (fake or legitimate).
• How were people recruited to participate?
• Public warnings and announcements prior to the event.

Don't Include:

• Any wording which directly states or implies that the business is/was illegitimate, or that a vulnerability existed.
• Anything that wasn't reasonably knowable at the time of the event.

There could be more than one section here. If the same platform is involved with multiple incidents, then it can be linked to a main article page.

The Reality

This sections is included if a case involved deception or information that was unknown at the time. Examples include:

• When the service was actually started (if different than the "official story").
• Who actually ran a service and their own personal history.
• How the service was structured behind the scenes. (For example, there was no "trading bot".)
• Details of what audits reported and how vulnerabilities were missed during auditing.

What Happened

The specific events of the loss and how it came about. What actually happened to cause the loss and some of the events leading up to it.

Key Event Timeline - BSV Multi-Sig Exploited

Date	Event	Description
November 7th, 2020	Main Event	Expand this into a brief description of what happened and the impact. If multiple lines are necessary, add them here.

Technical Details

This section includes specific detailed technical analysis of any security breaches which happened. What specific software vulnerabilities contributed to the problem and how were they exploited?

Total Amount Lost

The total amount lost has been estimated at $90,000 USD.

How much was lost and how was it calculated? If there are conflicting reports, which are accurate and where does the discrepancy lie?

Immediate Reactions

How did the various parties involved (firm, platform, management, and/or affected individual(s)) deal with the events? Were services shut down? Were announcements made? Were groups formed?

Ultimate Outcome

What was the end result? Was any investigation done? Were any individuals prosecuted? Was there a lawsuit? Was any tracing done?

Total Amount Recovered

There do not appear to have been any funds recovered in this case.

What funds were recovered? What funds were reimbursed for those affected users?

Ongoing Developments

What parts of this case are still remaining to be concluded?

General Prevention Policies

Multi-signature exploits are rare, and based on the case history, appear to be preventable by proper professional review and/or only using established setups that have been around for over a year.

Individual Prevention Policies

No specific policies for individual prevention have yet been identified in this case.

For the full list of how to protect your funds as an individual, check our Prevention Policies for Individuals guide.

Platform Prevention Policies

Policies for platforms to take to prevent this situation have not yet been selected in this case.

For the full list of how to protect your funds as a financial service, check our Prevention Policies for Platforms guide.

Regulatory Prevention Policies

No specific regulatory policies have yet been identified in this case.

For the full list of regulatory policies that can prevent loss, check our Prevention Policies for Regulators guide.