Security News > 2021 > May > Tech industry quietly patches FragAttacks Wi-Fi flaws that leak data, weaken security

He also identified flaws in the way frame aggregation - combining multiple network data frames - and frame fragmentation - splitting network data frames into smaller pieces - are implemented that magnify the impact of potential attacks.

The 802.11 frame aggregation flaw involves flipping an unauthenticated flag in a frame header, which allows the encrypted data payload to get parsed as if it were multiple aggregated frames instead of a simple network packet.

As for the two frame fragmentation design flaws, one has to do with the fact that while all the fragments of a frame are encrypted with the same key, receivers of the data aren't required to verify this.

The various implementation flaws include issues like data receivers not checking whether fragments belong to the same frame, which lets an attacker mix and match forged frames, not checking whether frame fragments are encrypted or not, and manipulating handshake messages to inject plaintext aggregated frames.

CVE-2020-26144: Accepting plaintext A-MSDU frames that start with an RFC1042 header with EtherType EAPOL. CVE-2020-26140: Accepting plaintext data frames in a protected network.

CVE-2020-26143: Accepting fragmented plaintext data frames in a protected network.

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https://go.theregister.com/feed/www.theregister.com/2021/05/12/krack_hack_wifi/