90 lines
4.8 KiB
Plaintext
90 lines
4.8 KiB
Plaintext
-----BEGIN PGP SIGNED MESSAGE-----
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Hash: SHA512
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I was pleased to be a participant in Powers of Tau, having served as the
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Zcash Company’s DevOps engineer during 2016-2017, and contributed some
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suggestions to the original ceremony.
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For the purposes of my report, the most important fact to disclose,
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which I must stress seems unconnected to my participation in the
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ceremony, is that I discovered I was hacked about a week beforehand. My
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router was popped and being tunneled/VPN’d into, and there was
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unprivileged access to my desktop computer complete with the hijacking
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of my DBUS user session enabling the attacker(s) to spy on my screen
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with XRDP. This was the case for a period of about two weeks in
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February, though it’s possible the targeting began earlier.
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Even as this is the first time any equipment of mine had been
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compromised in over a decade, and it’s somewhat embarrassing to admit
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since I make my living by securing systems and being trusted, I can
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reveal some of the methodology. At the time I was hacked, I was
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experimenting with Tor’s DNSPort as my primary means of domain name
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resolution, and I was running an open resolver which was exposed to the
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internet. I had also enabled UPnP and the media/streaming services of my
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router, and had set up SNMP to control the router. My best understanding
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is that a malicious DNS server was used to obtain the privileges of the
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loopback interface. Later, an unconfigured installation of FreeRADIUS on
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my system (which has a client grant for localhost in its default
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configuration) was exploited in order to give the attacker their own
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user on my machine. In addition to the hijacking of my DBUS user session
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and the remote viewing which occurred for days on end unbeknownst to me
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at the time, I discovered several levels of compromise and daemons which
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had been reconfigured, including MiniDLNA/minissdpd, PPD/pptpd, OpenVPN
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and snmpd.
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Needless to say, figuring this out prompted me to replace my router,
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re-install my operating system, revoke keys and shift passwords, and led
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to several sleepless nights spent investigating, yet ironically prepared
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or positioned me in a way for the ceremony. The strangest part of the
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whole episode is that I ended up having some conversation with one of
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the people who was hacking me via IRC, and to this day it seems they
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were just curious and nothing of value was taken. The lesson which I can
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impart to others is to please disable UPnP, and be wary of defaults and
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of keeping stuff installed which you don’t need!
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So… now for the computation, which occurred on March 9th. For a period
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of days before the ceremony, I essentially “went dark”, e.g. stopped
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posting on social media, and all traffic on my LAN was routed through
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the Tor network. Working out of my apartment, I used a computer which I
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have maintained for air-gap operations; which has never been connected
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to the internet. I transferred the challenge and the Rust
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code+dependencies via a USB stick. Both the compute node and my regular
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computer ran the ‘testing’ distribution of Debian Linux, and were fully
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updated in all respects including firmware. In addition, those machines
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had hardening applied to make things more secure. To be specific, I ran
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the latest grsecurity kernel in the 4.4.x stable series. I firewalled
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the machine(s) so that both incoming and outgoing packets had a default
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'DROP' policy, and the few protocols which I wanted to use would be
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explicitly added. I leveraged the AppArmor LSM with all available
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profiles enforced and enabled, and I also kept auditd logs which
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indicated no unusual activity or syscalls.
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With that said, here’s the b2sum of my response:
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548c67a73e0e33cd8c8d00f23963870ba5bfb8637ebeacc6541ed607b5edc8e7db1593d22804688f3cc4c788a750f7f8ec57aa7f122f3fa6d86ff5bc11a26940
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Lastly I want to note in advance that the key I'm using to sign my
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attestation presently (which was on a smartcard, so I have no indication
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it was stolen), 0xB604C32AD5D7C6D8, will nonetheless be revoked at the
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end of March 2018.
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Regards,
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Kevin Gallagher
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@ageis
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