A mainstream hardware cold wallet suffered a systemic defect in its random number generation algorithm, allowing attackers to compromise approximately 5000 wallets and steal 1755 BTC valued at around $110 million (7.43 billion RMB). The incident, confirmed on August 4, marks the largest hardware wallet security breach in crypto history because the flaw existed at the foundational level of private key generation rather than in network defenses.
Victims had relied on the common assumption that offline cold storage provides ultimate protection, yet the non-random RNG reduced the effective keyspace dramatically, enabling feasible brute-force attacks. Historical precedents show similar RNG weaknesses have repeatedly undermined wallet security across platforms including Android implementations and various hardware chips.
The event underscores that cold storage security depends entirely on correct implementation of cryptographic primitives at every layer, from hardware entropy sources to firmware. Experts recommend avoiding blind trust in any single device, verifying third-party audits, and diversifying storage across multiple solutions including open-source options.
Event Details
The breach did not involve sophisticated network intrusions or social engineering. Instead, the wallets generated private keys from a predictable subset of possible random numbers, turning an astronomically large theoretical space into a searchable range. Attackers who identified the bias pattern could target that limited space efficiently.
Root Cause Analysis
Hardware wallets are designed to generate and store private keys offline. Private key creation relies on a cryptographically secure random number generator (RNG). When the RNG contains systematic bias, generated keys cluster in a much smaller subspace, making exhaustive search practical. This is not a new class of issue; similar RNG failures have appeared in Android Bitcoin wallets in 2013, side-channel attacks on keycard chips in 2020, and firmware-level RNG problems reported in 2023.
Recommendations
- Do not treat the “cold storage” label as a guarantee of security; demand publicly available third-party audit reports before purchase.
- Distribute assets across multiple devices and seed phrases so that compromise of one wallet does not result in total loss.
- Prefer open-source hardware wallet solutions where the community can independently review the RNG implementation and entropy collection mechanisms.
