CVE-2022-35916 in OpenZeppelin
Summary
by MITRE • 08/02/2022
OpenZeppelin Contracts is a library for secure smart contract development. Contracts using the cross chain utilities for Arbitrum L2, `CrossChainEnabledArbitrumL2` or `LibArbitrumL2`, will classify direct interactions of externally owned accounts (EOAs) as cross chain calls, even though they are not started on L1. This issue has been patched in v4.7.2. Users are advised to upgrade. There are no known workarounds for this issue.
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Analysis
by VulDB Data Team • 08/02/2022
The vulnerability identified as CVE-2022-35916 affects OpenZeppelin Contracts version 4.7.1 and earlier, specifically impacting smart contracts that utilize cross chain utilities for Arbitrum Layer 2 networks. This flaw resides in the `CrossChainEnabledArbitrumL2` and `LibArbitrumL2` components designed to facilitate cross chain communication between Ethereum L1 and Arbitrum L2. The issue stems from improper handling of transaction origin detection, where the system incorrectly categorizes direct interactions initiated by externally owned accounts as cross chain calls despite these transactions originating directly on the Arbitrum L2 network rather than being relayed from L1.
The technical implementation flaw manifests in the contract's logic for determining transaction source and routing. When externally owned accounts interact directly with contracts deployed on Arbitrum L2, the system fails to distinguish between genuine cross chain transactions that originate from L1 and direct L2 transactions initiated by EOAs. This misclassification occurs because the validation mechanism does not properly verify the actual chain of origin for incoming transactions, leading to incorrect routing and processing decisions. The vulnerability creates a fundamental misalignment between transaction semantics and contract behavior, where legitimate L2 operations are treated as cross chain communications requiring additional security checks and processing overhead.
This misclassification has significant operational implications for smart contract security and functionality. Contracts that rely on proper cross chain detection for access control, transaction validation, and security protocols may inadvertently allow unauthorized access or process transactions incorrectly. The flaw essentially undermines the intended security model of cross chain communication by treating direct L2 interactions as potentially malicious cross chain operations, which could lead to unexpected behavior in permissioned systems or automated transaction processing. Additionally, the vulnerability affects the integrity of cross chain communication protocols by introducing incorrect assumptions about transaction origins, potentially compromising the security assumptions of smart contracts that depend on proper chain origin verification.
The vulnerability is categorized under CWE-284 Access Control Bypass, which specifically addresses improper access control mechanisms that allow unauthorized access to resources or functionality. From an attack perspective, this flaw could be exploited to bypass intended access controls, though no direct exploitation paths are documented since the issue primarily affects legitimate transaction processing rather than creating new attack vectors. The remediation requires upgrading to OpenZeppelin Contracts version 4.7.2 or later, which implements corrected transaction origin detection logic. This upgrade addresses the core validation mechanism by properly distinguishing between L1 cross chain transactions and direct L2 interactions through enhanced chain identification protocols. Organizations should implement immediate patch management procedures to ensure all contracts utilizing the affected cross chain utilities are updated, as the vulnerability cannot be mitigated through workarounds due to its fundamental nature in the transaction processing logic.
The impact extends beyond immediate security concerns to affect contract reliability and expected behavior in cross chain environments. Smart contracts that depend on proper transaction routing for their functionality may experience incorrect processing, leading to potential financial losses or operational failures. The vulnerability demonstrates the complexity of cross chain security implementations and highlights the importance of thorough testing across different chain environments. Organizations implementing cross chain smart contracts should conduct comprehensive security audits to identify other potential vulnerabilities in their cross chain communication protocols and ensure proper chain origin verification mechanisms are in place. This case underscores the critical need for precise transaction validation in multi chain environments where the distinction between different transaction origins directly impacts contract security and functionality.