Optimism Fixes Bugs on Testnet Following Alert from Arbitrum

Optimism has addressed security vulnerabilities on its testnet just weeks after a warning from its direct competitor, Arbitrum.

Optimism Fixes Bugs on Testnet Following Alert from Arbitrum

Layer 2 Optimism (OP Mainnet) recently patched two vulnerabilities on its testnet after receiving information about discrepancies in the system's fraud-proofing mechanism on March 22, 2024.

Notably, the entity that detected and reported the vulnerabilities back to Optimism was Offchain Labs, the organization behind the Arbitrum layer-2 solution, Optimism's direct competitor.

According to Offchain Labs' description, the vulnerabilities allowed malicious actors to force OP Stack's fraud-proof mechanism to accept a falsified blockchain history or obstruct the system from accepting an accurate chain history. Implementing fraud-proof is a crucial step to provide layer-2 solutions with a verifiable evidence framework to ensure data accuracy, rather than relying on the honesty of network participants as it stands today.

• Read more: What are the Stages of Layer-2?

The issue stemmed from deficiencies in how the system handles time counters from the fraud-proof mechanism.

Offchain Labs' post illustrated the problem using a chess game analogy, where each player has a specific amount of "credit time" to move their pieces. If a player fails to move within 7 days, they are considered to have forfeited.

However, managing time across multiple players in a game complicates matters.

If we divide into two teams, each with its own credit time, we must ensure that there are no "traitors" within a team exploiting their credit time to harm their own side.

Thus, managing credit time needs meticulous design to prevent malicious actors from exploiting and disrupting the entire game. This is a significant challenge in fraud-proof protocol design.

Offchain Labs stated: "Time counters are one of the subtlest and often trickiest aspects to handle."

Offchain Labs also confirmed that Optimism has successfully implemented corrective updates to its testnet.

Representatives from OP Labs also expressed gratitude to Offchain Labs for contributing to the network's security.

Arbitrum and Optimism are among the earliest layer-2 solutions and continue to lead in scaling Ethereum's second layer, with TVLs (Total Value Locked) at the time of writing standing at $16.2 billion and $6.3 billion, respectively.

Statistics of leading layer-2 solutions on Ethereum as of the morning of April 27, 2024. Source: L2Beat