Cronos Halts Blockchain After $75M Tectonic DeFi Exploit

Cronos halted its entire blockchain on Sunday after an attacker exploited Tectonic, the network’s largest decentralized lending protocol, in an incident estimated to have caused roughly $75 million in losses.

Launched by Crypto.com in 2021, Cronos is closely connected to the cryptocurrency exchange and supports lower-cost transactions across its ecosystem. CRO serves as the network’s native token, while Tectonic has emerged as one of its most prominent decentralized finance (DeFi) applications.

The exploit appears to have centered on TONIC, Tectonic’s native token, which users could deposit as collateral to borrow other crypto assets. Before the attack, TONIC had only about $1.34 million in liquidity and approximately $11,000 in daily trading volume, making it vulnerable to significant price swings.

Blockchain data indicates the attacker drove TONIC’s price roughly 100 times higher within about 20 minutes. The inflated tokens were then deposited into Tectonic as collateral, allowing the attacker to borrow more valuable assets against them.

TONIC carried a 20% collateral factor, meaning $100 worth of recognized collateral could support around $20 in borrowing.

The impact on Tectonic was substantial. According to DefiLlama, the lending protocol held approximately $121.7 million in total value locked (TVL) on August 26, representing nearly half of all funds deposited across Cronos DeFi. By Monday, Tectonic’s TVL had plunged to around $3 million.

Cronos can operate with a maximum of 100 validators, making it possible for participants to coordinate a network shutdown relatively quickly. The move echoes BNB Chain’s response to its October 2022 bridge exploit, when validators paused the blockchain and recovered nearly $470 million of roughly $570 million stolen.

The Tectonic attack also follows recent DeFi incidents involving price manipulation and thin liquidity. Moonwell suffered a similar collateral manipulation exploit last week, while a roughly 3% move in a thin Pendle market triggered about $36 million in liquidations on Morpho.

As of Monday morning, Cronos and Tectonic had not announced a blockchain restart timetable or confirmed the final amount lost in the exploit.