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Date:      Wed, 4 Sep 2024 18:08:07 +0200
From:      Tomek CEDRO <tomek@cedro.info>
To:        Jan Behrens <jbe-mlist@magnetkern.de>
Cc:        freebsd-security@freebsd.org
Subject:   Re: Privileges using security tokens through PC/SC-daemon
Message-ID:  <CAFYkXj=zSvCczRckLM%2BV0ZV_jhDhvFKDeo-_Uwf_9eutC1Driw@mail.gmail.com>
In-Reply-To: <20240904104147.8c1e74632b2c6d4f6a759ee6@magnetkern.de>
References:  <20240904104147.8c1e74632b2c6d4f6a759ee6@magnetkern.de>

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On Wed, Sep 4, 2024 at 10:42=E2=80=AFAM Jan Behrens <jbe-mlist@magnetkern.d=
e> wrote:
> Hello,
> I'm using packages "pcsc-lite-2.2.2,2" and "polkit-124_3" and set
> "pcscd_enable" to "YES" in "/etc/rc.conf".
>
> My computer has a YubiKey 5 NFC with firmware version 5.7.1 connected
> to it. When I create an unprivileged user account and log in from a
> remote machine (through ssh), then this unprivileged user account can
> use "ykman" to access my security key and, for example, list stored
> credentials, generate one-time tokens, erase or temporariliy block the
> device (by providing a wrong PIN), or even effectively brick it (if no
> configuration password is set).

If the YubiKey is plugged to the USB port on the host where you run
ykman then usb read/write permissions may be the problem?

If the YubiKey is plugged to your local machine, you use gpg-agent to
ssh to a remote machine, and on that remote machine you can make ykman
to work on your local machine's YubiKey thats magic.

By the way there is a loud bug in various YubiKey tokens that allows
cloning the physical tokens and/or private key access/recovery caused
by bug in Infineon's library [1].

[1] https://www.yubico.com/support/security-advisories/ysa-2024-03/

--=20
CeDeROM, SQ7MHZ, http://www.tomek.cedro.info



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