Elimination Point Device Mitigates Man-in-the-Middle Attacks in Redundant Paths

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Solution Overview

Problem

In deterministic networks with 1+1 redundant paths, existing security measures are inadequate to detect and mitigate man-in-the-middle attacks, which can disrupt network operations by allowing malicious packets to be injected into redundant paths, compromising the integrity of data transmission.

Innovation Solution

The implementation of a system where an elimination point device and a replication point device use a shared master secret to compute and verify message integrity checks (MICs) for incoming packets, ensuring that only valid packets are forwarded, and initiating mitigation actions when malicious packets are detected.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If 1+1 redundant network paths are used to ensure network reliability, then network availability is improved, but the system becomes vulnerable to man-in-the-middle attacks where malicious packets can be injected into one of the redundant paths

Engineering Contradiction:
Improvenetwork availabilityVSAvoidman-in-the-middle attack vulnerability
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an elimination point device as an intermediary that sits between the redundant network paths and the destination. This intermediary device receives packets from both primary and secondary paths, verifies their authenticity using MIC checks, and selectively forwards only legitimate packets while blocking malicious ones. The intermediary acts as a security gatekeeper that resolves the contradiction by adding verification capability without disrupting the redundant path architecture.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent implements preliminary security measures by computing Message Integrity Checks (MICs) at the source device before packets are transmitted through the redundant paths. The elimination point device already has the expected MIC values stored, allowing it to perform rapid verification when packets arrive. This preliminary action of pre-computing and pre-storing verification data enables the system to quickly identify and block malicious packets without adding significant latency.

Inventive Principle:
Principle #10Preliminary action

2Object-affected harmful factors

If security verification mechanisms are added to detect malicious packets in redundant paths, then network security is improved, but device complexity increases due to additional verification operations

Engineering Contradiction:
Improvemalicious packet detection capabilityVSAvoidverification operation complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent uses copying by creating MIC values that are derived from the original data but serve as independent verification tokens. The source device computes MICs as copies of the data's cryptographic fingerprint, and the elimination point device stores these MIC copies for comparison. When packets arrive, the elimination device computes MICs from the received data and compares them against the stored copies. This copying approach allows verification without requiring complex real-time cryptographic operations, simplifying the verification process while maintaining security.

Inventive Principle:
Principle #26Copying

3Reliability

If MIC verification is performed on all incoming packets from redundant paths, then packet integrity is ensured, but processing time increases due to additional verification steps

Engineering Contradiction:
Improvepacket integrityVSAvoidpacket processing time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent implements preliminary action by pre-computing and storing the expected MIC values at the elimination point device before any packets are transmitted. When packets arrive from the redundant paths, the elimination device simply compares the received MIC against the pre-stored expected MIC, rather than performing full cryptographic verification in real-time. This preliminary preparation of verification data dramatically reduces the processing time required for each packet while ensuring integrity.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent changes the verification parameter from complex cryptographic validation to simple MIC value comparison. By transforming the verification process into a straightforward equality check between received MIC and stored MIC, the system maintains packet integrity verification while minimizing processing time. The MIC itself is designed as a compact parameter that can be quickly computed and compared, changing the verification approach from time-intensive cryptographic analysis to efficient parameter matching.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3766223B1Defeating man-in-the-middle attacks in one leg of 1+1 redundant network paths
Publication Date: 2022.11.02 CISCO TECHNOLOGY INC
  • EP3766223B1 patent drawingFigure 1
  • EP3766223B1 patent drawingFigure 2
  • EP3766223B1 patent drawingFigure 3A

AI summary

In one embodiment, an elimination point device in a network obtains a master secret from a network controller. The elimination point device assesses, using the master secret, whether an incoming packet received by the elimination point device from a redundant path between the elimination point device and a replication point device in the network includes a valid message integrity check (MIC). The elimination point device determines whether the incoming packet was injected maliciously into the redundant path, based on the assessment of the incoming packet. The elimination point device initiates performance of a mitigation action in the network, when the elimination point device determines that the incoming packet was injected maliciously into the redundant path.