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Improper Certificate Validation

CVE-2020-15134

High
8.7/10

Summary

Faye through version 1.3.0, there is a lack of certification validation in TLS handshakes. Faye uses em-http-request and faye-websocket in the Ruby version of its client. Those libraries both use the `EM::Connection#start_tls` method in EventMachine to implement the TLS handshake whenever a `wss:` URL is used for the connection. This method does not implement certificate verification by default, meaning that it does not check that the server presents a valid and trusted TLS certificate for the expected hostname. That means that any `https:` or `wss:` connection made using these libraries is vulnerable to a man-in-the-middle attack, since it does not confirm the identity of the server it is connected to. The first request a Faye client makes is always sent via normal HTTP, but later messages may be sent via WebSocket. Therefore it is vulnerable to the same problem that these underlying libraries are, and we needed both libraries to support TLS verification before Faye could claim to do the same. Your client would still be insecure if its initial HTTPS request was verified, but later WebSocket connections were not. This is fixed in Faye v1.4.0, which enables verification by default. For further background information on this issue, please see the referenced GitHub Advisory.

  • HIGH
  • NETWORK
  • HIGH
  • CHANGED
  • NONE
  • NONE
  • HIGH
  • NONE

CWE-295 - Improper Certificate Validation

The authenticity component of a web system stems from the ability to validate “Digital certificates”, which (i) establish trust between two or more entities sharing data over a network; (ii) ensure data at rest and transit is secure from unauthorized access; and (iii) check the identity of the actors that interact with the system. An application with absent or ineffective certificate validation mechanisms allows malicious users, impersonating trusted hosts, to manipulate the communication path between the client and the host, resulting in unauthorized access to data and to the application’s internal environment, and potentially enabling man-in-the-middle attacks.

References

Advisory Timeline

  • Published