Heartbleed Overview

Heartbleed Overview

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  whoami Dominic White CTO @SensePost We Hack | Build | Train | Scan Stuff @singe / @sensepost [email protected] info/research/job @sensepost.com
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  What Happened • 7April 2014 – Vulnerability announced to the world with a website, OpenSSL vulnerability announcement and new code release (1.0.1g) – Found by two groups; Google Security Team (Neel Mehta & Condenomicon) • Told that private keys to SSL certificates could be exposed – uh oh • Operating systems had not packaged the new release, so many were vulnerable • Many big name companies were vulnerable; Big Tech names, Banks, Law Enforcement, Intelligence Agencies • Online testers appeared, and were quickly swamped • But ….
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  What is it? •Vulnerability in a widely used cryptographic library – i.e. lots of Unix things use this to do encryption • Vulnerability specific to SSL Heartbeats – RFC 6520 https://tools.ietf.org/html/rfc6520 • Introduced on Dec 31 2011 by Dr Stephen Henson • Allows you to read parts of a program memory – Buffer Over Read
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  Demo • Extracting cookies& private SSL keys from a vulnerable server
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  Why does itwork • OpenSSL is just the library, the actual process is something like Apache, Nginx, Dovecot, Exim etc. • These processes have a HEAP, in which data used by the process is stored. – If the process is active, it changes a lot • Certificate private keys are made up of two large prime numbers; we can find these if they were used recently
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  The slow pathto enlightenment • Initial testers looked for vanilla SSL on port 443 using TLS v1.1 – Most famous and first PoC by Jared Stafford; ssltest.py • But: – SSL runs on non-standard ports – Some servers didn’t support TLS v1.1 – SSL can be invoked on clear-text ports with STARTLS • STARTTLS is different for different protocols – Clients are vulnerable too! – Lots of debate about whether keys could be grabbed • CloudFlare challenge cleared that up – IDS signatures were quickly defeated
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  Meanwhile …. • #heartbleedvirus •Bruce Schneier – “On the scale of 1 to 10, this is an 11.” • I’m not Vulnerable, the scanner said so! • Claims of NSA backdoor bogey men • EVERYBODY CHANGE ALL YOUR PASSWORDS! – NO WAIT, CHANGE THEM AGAIN!
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  How Bad WasIt? • Masscan (Robert Graham) – 615 268 / 28 581 134 – After one month 318 239 • Our clients – 1.8% when it broke – Offered free “complete” scan – 24 / 224 186
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  Tactical Defence Fix theVuln • Patch it – OpenSSL >= 1.0.1g – Old versions < 1.0.1 unaffected • Disable it – Firewall, VPN? • Reconfigure it – Disable heartbeats – Enable Perfect Forward Secrecy • IDS it? – Do not rely on this Cleanup • Change certificates – Revoke the old ones • Reset sessions – i.e. invalidate all cookies • Change passwords – Only affected user-stores
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  Defence in Depth •One 0day shouldn’t ruin your day – But this one was tricky 1. Early alerting 2. Response procedures (IR) 3. Ability to act quickly (devsecops) 4. Avoid heterogeneity/monocultures?
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  The State ofOpenSSL’s Future • Massive amount of legacy code • Incredibly complex to maintain – 2 people effectively doing most of it • C considered harmful today – Pointer arithmetic makes problems • FIPS certification dangerous – Certifies bad crypto & bad implementations • OpenBSD’s OpenSSL rampage -> LibreSSL • OpenSSL just got a ton of funding
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  Eye Openers • Wethought OpenSSL was okay – Ok, lots didn’t, but nobody did anything about it – We think lots of other things are ok – ESR’s Linus’ Law: “Given enough eyeballs, all bugs are shallow” • But! – We found the bug – People actually patched it • Others – The rise of the branded bug – The trail of fakes • Media still drives reactions
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  Thanks & References •Hackerfantastic – Tool & Presentation • Erratarob – Tool/s & blogs • XKCD – Comics! • Elpartydiablo & xnvx.com – Background