CVE-2015-20112 in RLPx
Summary
by MITRE • 06/30/2025
RLPx 5 has two CTR streams based on the same key, IV, and nonce. This can facilitate decryption on a private network.
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Analysis
by VulDB Data Team • 06/30/2025
The vulnerability identified as CVE-2015-20112 resides within the RLPx protocol implementation, specifically affecting version 5 of the protocol used in Ethereum's peer-to-peer networking. This issue manifests in the cryptographic implementation where two distinct Counter (CTR) streams utilize identical key, initialization vector, and nonce parameters. The RLPx protocol serves as the foundation for secure communication between Ethereum nodes, establishing encrypted channels for transaction propagation, block synchronization, and other critical network operations. When multiple CTR streams operate with identical cryptographic parameters, it creates a fundamental weakness in the encryption scheme that undermines the security guarantees intended by the protocol.
The technical flaw stems from a critical error in the cryptographic key management and stream initialization process within RLPx version 5. In proper CTR mode implementations, each encryption stream must maintain unique nonce values to prevent cryptographic collisions and maintain confidentiality. However, in this vulnerability, the same nonce is reused across multiple CTR streams, creating a scenario where an attacker can exploit the predictable nature of the encryption. The reuse of identical key, IV, and nonce combinations across different streams allows for mathematical relationships to be established between the encrypted data streams, potentially enabling an attacker to perform statistical analysis or direct cryptographic attacks that would normally be prevented by proper nonce uniqueness.
The operational impact of this vulnerability extends beyond simple data confidentiality breaches within the Ethereum network. Private networks that rely on RLPx for secure communication between nodes become susceptible to eavesdropping and data manipulation attacks. Attackers can potentially decrypt sensitive transaction data, manipulate network communications, or gain insights into network topology and node behavior patterns. This weakness particularly affects networks where nodes communicate using the same cryptographic parameters, creating a vector for attackers to compromise multiple nodes simultaneously if they can observe the network traffic. The vulnerability essentially undermines the core security assumptions of the RLPx protocol, potentially allowing unauthorized access to private network communications and compromising the integrity of the entire Ethereum network infrastructure.
The implications of this vulnerability align with CWE-327, which addresses the use of weak cryptographic algorithms and improper implementation of cryptographic functions. This specific weakness represents a failure in cryptographic key management and nonce uniqueness requirements that directly violates established security practices. From an ATT&CK framework perspective, this vulnerability maps to the T1046 technique for network service scanning and T1566 for credential harvesting, as attackers could leverage the compromised encryption to gain unauthorized access to network resources. The vulnerability also relates to T1571 for application layer protocol, since it affects the secure communication layer that Ethereum nodes use to interact with each other. Mitigation strategies should include immediate protocol upgrades to versions that properly implement unique nonce values for each CTR stream, along with comprehensive network monitoring to detect any exploitation attempts. Organizations should also implement additional security layers such as network segmentation and traffic analysis to reduce the impact of potential exploitation, while ensuring that all nodes in the network are updated to versions that address this specific cryptographic weakness. The vulnerability underscores the critical importance of proper cryptographic implementation and the potential catastrophic consequences of seemingly minor flaws in security-critical protocols.