Transport Layer Security (TLS) provides secure communication between systems over the internet by encrypting the data sent between them. In this
process, the role of hostname validation, combined with certificate validation, is to ensure that a system is indeed the one it claims to be, adding
an extra layer of trust and security.
When hostname validation is disabled, the client skips this critical check. This creates an opportunity for attackers to pose as a trusted entity
and intercept, manipulate, or steal the data being transmitted.
To do so, an attacker would obtain a valid certificate authenticating example.com, serve it using a different hostname, and the
application code would still accept it.
What is the potential impact?
Establishing trust in a secure way is a non-trivial task. When you disable hostname validation, you are removing a key mechanism designed to build
this trust in internet communication, opening your system up to a number of potential threats.
Identity spoofing
If a system does not validate hostnames, it cannot confirm the identity of the other party involved in the communication. An attacker can exploit
this by creating a fake server and masquerading it as a legitimate one. For example, they might set up a server that looks like your bank’s server,
tricking your system into thinking it is communicating with the bank. This scenario, called identity spoofing, allows the attacker to collect any data
your system sends to them, potentially leading to significant data breaches.
