BitGo Clears Itself in Unocoin Incident; Exchange Keys Signed Transfers

Custody provider BitGo concluded on November 13 that its systems were not breached in the Unocoin security incident, stating that the Indian exchange authorized a set of outgoing Ethereum transactions using its own user and backup keys — and that BitGo's key was never used. The finding shifts the investigation away from the custodian and back onto Unocoin, which has suspended all services, including user logins, while it rebuilds its infrastructure.

Unocoin detected unauthorized activity on its platform on November 6. The response was fast. The exchange asked Fireblocks to freeze its enterprise accounts at 11:24 UTC and sent the same request to BitGo five minutes later, at 11:29 UTC. Both freezes were confirmed shortly after the requests came in.

The freezes did not end the episode. On November 9, further unauthorized actions pushed Unocoin to shut down every service on the platform, including logins. The exchange opened an investigation into a potential compromise of its servers and said it planned to rebuild its systems from scratch — a job it estimated at four to five working days. On November 12, Unocoin spotted additional outgoing Ethereum transactions from its BitGo wallet infrastructure and escalated them for review.

What does the key structure reveal?

Unocoin ran a 2-of-3 multisig arrangement: a user key, a backup key and BitGo's key, with any two signatures sufficient to approve a transaction. That structure is the crux of BitGo's defense. Its November 13 investigation concluded the Ethereum transactions were signed with Unocoin's own user key and backup key, without BitGo's key involved at any point.

The working theory — and it remains a theory while the investigation continues — is a possible exploitation of the backup key mechanism within Unocoin's setup. BitGo also stated that no other clients were affected by the incident.

The operational implication is straightforward. When two of three keys sit under one organization's control, the safeguard depends on how carefully that organization protects them. A compromised server holding or reaching both keys could, in principle, approve transactions without the custodian ever knowing. Whether that happened here is precisely what the investigation must determine.

Where do customers stand?

Unocoin's position is that the damage is contained. The exchange says it keeps over 90% of customer assets in cold storage — offline wallets not connected to the internet. If that figure holds, the bulk of user funds sat outside the hot infrastructure that appears to have been targeted.

The exchange also says there have been no confirmed losses so far. That claim sits alongside a less comforting admission: Unocin does not yet have full visibility into every transaction. The exchange attributes the gap to the complexity of change addresses — the addresses that receive leftover funds from a transaction and can make tracing the full path of money harder than following a single transfer.

Until Unocoin accounts for every outgoing transaction, including those routed through change addresses, "no confirmed losses" describes what has been verified, not a final tally. Customers cannot log in at all until the rebuild finishes.

What does this change for exchanges running multisig?

For operators, the lesson concerns key placement, not custodian choice. If the investigation confirms the backup key mechanism was exploited, other platforms running similar 2-of-3 setups may have to revisit where their backup keys live and who can reach them. The episode is a reminder that a multisig arrangement is only as decentralized as the physical and operational separation of its keys — and that a freeze request to a custodian, however prompt, does nothing once two signatures under one roof have already moved the funds.

Unocoin's four-to-five-day rebuild estimate gives the exchange a narrow window to complete its transaction accounting, including change-address tracing, before it must face customers with a verified balance sheet rather than a provisional one.