This scenario describes a man-in-the-middle (MITM) attack where the attacker is able to intercept traffic between the user and the legitimate website, and present a spoofed/fake certificate to the user.
The specific things that have happened are:
- Certificate interception: The attacker was able to intercept the user's request for the legitimate certificate from the website.
- Certificate spoofing: The attacker generated/obtained an illegitimate certificate impersonating the real website, and presented this fake certificate to the user.
- Certificate acceptance: The user's browser accepted the fake certificate as valid, not detecting that it was illegitimate.
- Encryption compromise: With the fake certificate, the attacker can now decrypt and monitor the user's traffic that should have been encrypted with the real certificate.
- Identity compromise: The user believes they are communicating safely with the legitimate website, when in reality the attacker is intercepting all traffic.
- Integrity compromise: The attacker can now not only read the intercepted traffic, but also modify it before passing it on to the user/website.
So in summary, this scenario encompasses an interception, spoofing, and undetected acceptance of an illegitimate certificate, allowing the attacker to compromise encryption, identity, and integrity in a MITM attack. The user's traffic is exposed thinking the connection is safe.