Ethereum Classic

Ethereum Classic receives a B- risk grade (35/100) from Hindenrank, where lower scores indicate lower risk. Elevated risk — four proven 51% attacks in 2019-2020 and a low attack cost relative to market cap, partially offset by post-attack security improvements and the 2025 Olympia upgrade. Ethereum Classic is the original Ethereum blockchain that continued after the 2016 DAO fork, maintaining the principle that blockchain transactions should be immutable. With a market cap of approximately $1.34 billion (ranked #56) and EVM smart contract functionality, ETC is the largest proof-of-work smart contract platform following Ethereum's transition to proof-of-stake. Its B- grade reflects four confirmed 51% attacks in 2019-2020 (resulting in ~$8M in double-spend losses), mitigated by subsequent security upgrades including ETChash and the MESS reorganization penalty system. The 2025 Olympia upgrade introduced fee burns, treasury allocation, and DAO governance, improving the economic model.

The key risks identified for Ethereum Classic are: (1) Ethereum Classic suffered four 51% attacks between 2019 and 2020, with deep chain reorganizations enabling approximately $8 million in double-spend losses at exchanges. While the ETChash algorithm modification and MESS penalty system have been implemented as defenses, a 24-hour attack still costs approximately $144,000 as of October 2025 — within reach of well-funded attackers. (2) ETC competes directly with Ethereum for smart contract developers and users but with a dramatically smaller ecosystem. Most EVM tooling, DeFi protocols, and developer talent targets Ethereum mainnet. As Ethereum's EVM evolves with new features, ETC risks falling behind in compatibility, reducing its utility as a smart contract platform. (3) The ECIP-1017 monetary policy reduces block rewards 20% every ~2.5 years, progressively thinning the security budget. Combined with the 2025 Olympia fee burn, total miner revenue may decline faster than expected if network usage does not grow sufficiently to compensate. (4) The estimated cost of a 51% attack ($144K/day) is low relative to the market cap ($1.34B) and potential exploit profits. DeFi protocols deployed on ETC face a unique risk: chain reorganizations can roll back smart contract state, enabling state-manipulation attacks beyond simple double-spends.

Ethereum Classic scores 35/100 across eight risk dimensions: Mechanism Novelty: 0/15, Interaction Severity: 6/20, Oracle Surface: 2/10, Documentation Gaps: 3/10, Track Record: 10/15, Scale Exposure: 7/10, Regulatory Risk: 1/10, Vitality Risk: 6/10. The highest risk area is Scale Exposure at 7/10.

Among 56 rated L1 protocols on Hindenrank, Ethereum Classic ranks #31 by safety (lowest risk score = safest). Its 35/100 risk score and B- grade place it in the middle tier of L1 protocols.

Ethereum Classic scores 10/15 on the Track Record risk dimension, indicating some history of security incidents or exploits. Higher scores reflect more severe or frequent incidents. Review the full risk report for details.