Briefing

KiloEx, a decentralized exchange, suffered a sophisticated price oracle manipulation attack, resulting in the loss of approximately $7.5 million across its Base, opBNB, and BNB Smart Chain deployments. The exploit leveraged a critical vulnerability in the protocol’s MinimalForwarder contract, allowing an attacker to forge signatures and directly manipulate the KiloPriceFeed oracle. This incident underscores the systemic risk posed by inadequate access control mechanisms within complex DeFi architectures.

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Context

Prior to this incident, the DeFi ecosystem had seen a rise in price oracle manipulation attacks, often enabled by insufficient validation logic or centralized price feeds. Many protocols, including KiloEx, relied on multi-contract call chains for critical functions, creating an expanded attack surface where a single unchecked permission could compromise the entire system. The prevailing risk factors included unaudited or inadequately audited forwarder contracts and a lack of granular access control.

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Analysis

The attack vector exploited a missing access control check within KiloEx’s MinimalForwarder contract. This contract, part of a chained series (MinimalForwarder → PositionKeeper → Keeper → KiloPriceFeed) designed to update the price oracle, allowed arbitrary addresses to execute calls by submitting forged signatures without verifying the legitimacy of the call path. The attacker crafted a fake signature, impersonated an authorized address, and directly invoked the setPrices() function on the KiloPriceFeed oracle. This enabled the attacker to artificially depress asset prices, open leveraged long positions, then rapidly inflate prices to close positions for risk-free profit, systematically draining liquidity pools across multiple chains.

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Parameters

  • Protocol Targeted → KiloEx
  • Attack Vector → Price Oracle Manipulation (via forged signature and missing access control)
  • Financial Impact → $7.5 Million
  • Blockchain(s) Affected → Base, opBNB, BNB Smart Chain
  • Vulnerability → Missing Access Control in MinimalForwarder contract
  • Date of Incident → April 14-16, 2025

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Outlook

Immediate mitigation for similar protocols involves a comprehensive audit of all chained contract interactions, with a specific focus on robust access control and signature validation mechanisms within forwarder contracts. This incident will likely drive a re-evaluation of oracle security, emphasizing multi-source validation and decentralized oracle solutions to prevent single points of failure. The broader implication is a heightened standard for modular smart contract security, necessitating explicit permission checks at every step of a call chain.

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Verdict

The KiloEx exploit serves as a critical reminder that fundamental access control vulnerabilities, even in seemingly minor components, can lead to catastrophic financial losses across complex DeFi architectures.

Signal Acquired from → OneKey

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