The Patching Friars' AlmanacA calendar of CVE saints

October 23

DUHKHoly card for duhk, generated with AI (Claude, Anthropic) for the Lunario dei Frati Patchatori.CC BY-NC-SA 4.0 X9.31 DUHK CLAVIS OMNIBUS NOTA
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Saint DUHK, Who Guessed the Throwaway Key

Patron of pseudo-random generators with the key baked into the firmware, FortiGate VPNs, and secrets that were never secret.

Life

On 23 October 2017 Shaanan Cohney, Nadia Heninger and Matthew Green revealed DUHK: some devices, Fortinet's FortiGates among them, used the old ANSI X9.31 generator with a fixed key, hard-coded into the firmware and identical for everyone. Whoever knew it could predict the "random" numbers and decrypt the VPN and TLS traffic those devices protected. The name, "Don't Use Hard-coded Keys", was also the moral.

Prayer

O Saint DUHK, who guesses the dice because you have already seen them, let our keys not be born inside the firmware. Amen.

How to celebrate

Celebrated by updating FortiOS firmware and abandoning random generators with hard-coded keys, wherever they lurk.

A key written in the code is everyone's key.

Technical record

Disclosed on
October 23 2017
CVE
CVE-2016-8492
Product
Fortinet · Fortinet FortiGate

The implementation of an ANSI X9.31 RNG in Fortinet FortiGate allows attackers to gain unauthorized read access to data handled by the device via IPSec/TLS decryption.

Sources: duhkattack.com

Also remembered today

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