HTTPS MITM Detection via SNI and IP Discrepancy
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Solution Overview
Problem
The increasing interception of Transport Layer Security (TLS) connections by middlebox and antivirus products for visibility into network traffic weakens HTTPS security, particularly due to Server Name Indication (SNI) and self-signed certificates, making it difficult to detect man-in-the-middle (MITM) attacks effectively.
Innovation Solution
The method involves manipulating TCP, TLS, and HTTP settings to expose an unseen MITM by creating test conditions that leverage disjointed communication flows, including scrambling IP addresses and using alternate domain names or domain generation algorithms, to reveal inspection points during HTTPS communications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If middlebox and antivirus products intercept TLS connections for visibility into network traffic, then network security monitoring capability is improved, but HTTPS security is weakened
Solution Approach 1:
The patent performs preliminary actions by establishing alternative communication paths and pre-positioning detection mechanisms before MITM attacks can fully establish themselves. The system proactively monitors TLS handshakes and certificate validations to detect interception attempts before they compromise security.
Solution Approach 2:
The patent introduces intermediary detection systems that act as mediators between the client and server connections. These intermediaries monitor the TLS communication flow, validate certificate chains, and detect when unauthorized middleboxes are intercepting traffic, thereby maintaining security while allowing legitimate monitoring.
2Adaptability or versatility
If SNI and self-signed root certificates are deployed for HTTPS, then server flexibility and certificate management are improved, but overall transport layer security is weakened
Solution Approach 1:
The patent implements feedback mechanisms that continuously monitor certificate validation outcomes and SNI usage patterns. When anomalies are detected—such as unexpected self-signed certificates or mismatched SNI values—the system responds by alerting security personnel or blocking the connection, thereby maintaining security despite the flexibility provided by SNI and self-signed certificates.
Solution Approach 2:
The patent changes security parameters dynamically based on the type of connection and certificate being used. For connections using self-signed certificates or SNI, the system adjusts validation strictness, requires additional verification steps, or implements enhanced monitoring, thereby maintaining security adaptability to different certificate management scenarios.
3Measurement precision
If domain generation algorithms are used to generate alternate domain names, then detection capability against botnets is improved, but complexity of domain management increases
Solution Approach 1:
The patent implements self-service mechanisms where the domain generation algorithm automatically creates and manages alternate domain names without requiring manual intervention. The system autonomously generates DGA-style domains, monitors their usage, and retires them when no longer needed, thereby improving botnet detection while minimizing the operational complexity of domain management.
Data Source
AI summary
Various methods for detecting a man-in-the-middle (MITM) during HTTPS communications are disclosed including, in some aspects, establishing a TCP connection for the retrieval of a web page from a domain name using an alternate IP address that is different from the IP address of the target domain where receipt of the target web page in response to a HTTP GET message indicates that a MITM is present, using a domain name as the SNI in a TLS connection and an alternate domain name in a HTTP GET message where receipt of a target web page of the alternate domain name indicates that a MITM is present, and generating an alternate domain name using a domain generation algorithm and using the generated alternate domain name as the SNI in the TLS message where receipt of a certificate for the generated alternate domain name indicates that a MITM is present.