Comment by planb | Hacker News Reader

Comment by planb | Hacker News Reader

Unfortunately, I don't think the real world applications of this exploit are explained anywhere. From skimming the paper , it looks like the attacker needs to be able to a) run code on the victim's machine and b) trigger the encryption process ("For our cryptographic attacks, we assume the attacker runs unprivileged code and is able to interact with the victim via nominal software interfaces, triggering it to perform private key operations.")

So for a) it might be sufficient to run javascript and for b) of course there are ways to inject data into server processes, processing data submitted by clients is what servers are for.

But a happens on clients (web browsers) and b would be a way to extract encryption keys from servers. But in what case can an attacker run code on a machine where they can also trigger the encryption (constantly for an hour like in the demonstration)? The only thing that comes to my mind would be a server side code-execution-sandbox that runs SSL termination on the same machine.

edit: Maybe stealing client certificate keys?

Kim Zetter has a great post walking through some details and commentary across a few sources, related to the vulnerability - https://www.zetter-zeroday.com/apple-chips/

> The cryptographic key itself isn’t placed in cache. But bits of material derived from the key gets placed in the cache, and an attacker can piece these bits together in a way that allows them to reconstruct the key, after causing the processor to do this multiple times. The researchers were able to derive the key for four different cryptographic algorithms: Go, OpenSSL, CRYSTALS-Kyber and CRYSTALS-Dilithium.

> [Green] notes that in theory this attack might be used to break the TLS cryptography that a computer’s browser uses to encrypt communication between their computer and web sites, which could allow attackers to decrypt that communication to extract a user’s session cookie for their Gmail or other web-based email account and use it to log into the account as them.

Suppose you have a MITM attacker, e.g. hotel WiFi. You have any page not using TLS open in a background tab, which the attacker uses to inject javascript. Meanwhile there is a different page open via TLS which you're actively using, so your browser is constantly using the session key to encrypt the traffic. The attacker is now recording the encrypted session and after an hour they crack the session key and can use it to go back and decrypt the traffic.

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