iOS 11.1 ha risolto KRACK solo per iPhone 7 e successivi?

Sembra che tu fossi impeccabile con le tue domande. Diversi siti di notizie riportano lo stesso, ad esempio ArsTechnica menzioni:

Update: As Ars readers have pointed out, Apple's support documentation states that the iOS KRACK fix is available for iPhone 7 and later, and for the early 2016, 9.7-inch iPad Pro and later. It is unclear whether this means previous devices are still vulnerable, or they had previously not been vulnerable and thus didn't need an update. Ars has reached out to Apple for comment.

Modifica
Ho analizzato i commenti su ArsTechnica e ho trovato questo post. Dichiara quanto segue:

For iOS, the bug was fixed in iOS 10.3.3. I was able to establish a theory based on firmware analysis and tested the theory on a few devices running older and newer iOS firmware. The pattern was that devices with A8 processors were vulnerable (crashed the Wi-Fi chip) if running iOS 10.3.2 or earlier, but models with older processors were not vulnerable for any iOS version I could test. (I wasn't able to test any A9 or newer models running iOS 10.3.2 or earlier, but firmware analysis points to them being vulnerable as there were fixes in 10.3.3.)

Nel forum Macrumors ho trovato questo post , che dice qualcos'altro, non sono stato in grado di trovare la parte nelle trascrizioni fino ad ora. Forse qualcun altro può far luce su questo.

Yep apparently in the older devices iOS WPA2 implementation was not correctly done and as a side benefit are not vulnerable to KRACK. According to Steve Gibson of Security Now, iOS was not vulnerable to KRACK because they misimplemented the WPA2 specification. My guess is iP7 and up is when WPA2 was fixed and therefore now those devices need the patch! Perhaps Apple will relay this information soon to clear it up for all. That could mean the non iOS11 compatible devices are all fine as well.

Quindi questo potrebbe essere il motivo per cui esisteva solo una soluzione per i nuovi dispositivi.
Nel documento KRACK stesso, iOS 10.3.1 è stato contrassegnato come non vulnerabile alla ritrasmissione del terzo messaggio dell'handshake a 4 vie.

Citazione dal articolo :

In particular, Windows and iOS do not accept retransmissions of message 3 (see Table 1 column 2). This violates the 802.11 standard. As a result, these implementations are not vulnerable to our key reinstallation attack against the 4-way handshake.

Ma:

Unfortunately, from a defenders perspective, both iOS¹ and Windows are still vulnerable to our attack against the group key handshake. Additionally, because both OSes support 802.11r, it is still possible to indirectly attack them by performing a key reinstallation attack against the AP during an FT handshake.

^{1 Questo è iOS 10.3.1}

Quindi entrambi i sistemi operativi sono ancora vulnerabili, ma non quello che è "comunemente" noto come KRACK - che potrebbe sfruttare l'handshake a 4 vie. Suppongo che iOS 11.0 abbia implementato correttamente lo standard 802.11 e questo è stato risolto. (La descrizione nelle note delle patch mi sembra un po 'sfocata)

Ecco uno screenshot di quella tabella di fantasia: