Night of the living vulnerabilities: forever-days of IoT

Video: https://www.youtube.com/watch?v=OIYoe32biNk

In a tribute to Romero's masterpiece, we examined the resurgence of vulnerabilities we all thought dead. As soon as a security expert looks at the firmware and code of IoT devices, 2017 may as well be 1997: format string bugs, basic stack overflows and hardcoded credentials arise. Zero-days are actually forever-days.
We looked at a number of real world cases of industrial and consumer IoT devices we tested and broke, and besides analyzing the most common and most outstanding findings, we will wonder why we seem unable to kill these pests once and forever.

Transcript

1. NIGHT OF THE LIVING VULNS
   Roberto Clapis, Stefano Zanero
   CODEMOTION MILAN - SPECIAL EDITION
   10 – 11 NOVEMBER 2017
   

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2. A tale of
   horror and hope
   in the land of IoT
   Starring:
   Roberto Clapis
   Security Engineer
   Secure Network
   Stefano Zanero
   Associate Professor
   Politecnico di Milano
   

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3. ▪Smart hairbrush
   ▪Smart wine bottle
   ▪Smart egg tray
   ▪Smart salt shaker
   

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4. ▪Smart Plugs
   ▪Smart Keychain
   ▪Smart Thermostat
   ▪Smart Irrigation Controllers
   

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5. ▪Cooperative Robots
   ▪Insulin Pumps
   ▪Automotive
   ▪Surgical Robots
   

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6. THREAT MODEL
   ▪Internet facing but not
   designed for it
   ▪Contains PII
   ▪Safety critical
   

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7. WHAT ARE WE EXACTLY TALKING ABOUT?
   

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8. FORMAT STRING IN THERMOSTAT
   

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9. BUFFER OVERFLOW IN POS DEVICES
   

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10. BUFFER OVERFLOW IN POS DEVICES
    This is an
    fgets()
    

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11. SOMETIMES IOT DEVICES
    ARE NOT SMALL AND
    CUTE...
    

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12. DEFAULT PASSWORDS NEVER DIE
    

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13. DID YOU SAY CODE SIGNING?
    Any password works during boot
    No code signing or verification (!)
    What the... ?
    

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14. ZOMBIE VULNERABILITY MATRIOSKA
    FTP RETR /command/whatever read system info
    FTP STOR /command/command execute “commands”
    e.g., shell reboot
    shell uas_disable
    With no/hardcoded credentials!
    

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15. COPY-PASTA THAT SPAGHETTI CODE
    

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16. 1980 CALLED, THEY WANT THEIR VULNS BACK
    

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17. • Why are these vulns still alive?
    • What are the tools we can use?
    • To find out, and go beyond our own opinion, we
    brainstormed with tens of developers and openly twitter-
    stormed with the security community
    

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18. WHY ARE THEY STILL ALIVE
    ▪ Lack of awareness
    ▪ A senior developer was completely
    puzzled by the potential security
    risks of strcpy
    ▪ Perception that security
    vulnerabilities happen only to "the
    web guys"
    ▪ Out of memory is cool again but no
    one knows it
    ▪ Old code and technical debt
    ▪ Time to market pressure
    ▪ The security community is not
    providing viable solutions
    

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19. ▪ Stack overflow vulnerabilities "as if in the 90s"
    ▪ Often no memory segment protection
    ▪ No ASLR
    ▪ No W^X
    ▪ Grsec missing in action and...
    ▪ The default was until very recently
    --no_protect_stack (the opposite of all other
    architectures) for no reason at all!!!
    http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.d
    ui0491i/BCFGBAIC.html
    

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20. ▪Lack of IDE tools
    ▪Lack of emulators for extensive testing
    ▪There are no "safe(r)" libraries
    ▪Most of the tools we (can) recommend
    either do not exist in embedded or are
    not usable by developers
    

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21. ▪Fuzzing with AFL / libfuzzer
    ▪Compcert C
    ▪"Change language to..."
    ▪Address Sanitizer (no
    Linux/ARM yet)
    https://github.com/google/sanitiz
    ers/wiki/AddressSanitizer
    

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22. ▪Let people choose their
    analysis tools
    ▪Advanced threat
    modeling/secure coding
    training for all developers
    ▪"Consider all inputs
    (including sensors) hostile,
    always"
    

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23. ▪"Apply LangSec"
    ▪Look at the assembly output,
    especially on sensitive or
    crypto code. Unrealistic.
    ▪"Patch sbrk() to reboot rather
    than allowing malloc() to
    return 0"
    

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24. ▪ Create or use some safe libraries, e.g. to handle type safety,
    integer expansion/truncation, etc.
    ▪ https://github.com/mbedded-ninja/MFixedPoint/
    ▪ MISRA C and the JPL coding standard:
    ▪ https://yurichev.com/mirrors/C/JPL_Coding_Standard_C.pdf
    ▪ Simple cheat sheets and usable documentations:
    ▪ https://www.owasp.org/index.php/C-Based_Toolchain_Hardening_Cheat_Sheet
    ▪ https://github.com/intel/safestringlib/wiki/SDL-List-of-Banned-Functions
    ▪ https://scriptingxss.gitbooks.io/embedded-appsec-best-practices/
    ▪ Don't reinvent the wheel (updates, graphics libraries)
    ▪ https://mender.io
    ▪ https://ugfx.io
    

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25. ▪ Flawfinder
    ▪ Cppcheck:
    ▪ http://cppcheck.sourceforge.net
    ▪ Scitools:
    ▪ https://scitools.com/features
    ▪ Frama-C
    ▪ Clang Analyzer
    ▪ Enable stack protector
    

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26. What if you inherit a codebase?
    ▪ Get any and all documentation left behind, are there patterns in the kinds of bugs being
    fixed?
    ▪ Check if there are good tests in place already
    ▪ Lint the code
    ▪ Start with static analysis tools
    ▪ Look for bad/incompletely commented sections and TODOs
    ▪ Seek for inputs and uses of untrusted data and follow the breadcrumbs
    ▪ Seek for custom crypto code and kill it with fire
    ▪ Don't be afraid of refactoring
    

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27. ▪ For further information:
    ▪ https://www.amazon.com/Secure-Programming-Cookbook-
    Cryptography-Authentication/dp/0596003943
    ▪ https://www.amazon.com/Secure-Coding-2nd-Software-
    Engineering/dp/0321822137
    ▪ https://www.e-reading.club/bookreader.php/138815/Linden_-
    _Expert_C_Programming:_Deep_C_Secrets.pdf
    ▪ https://www.amazon.com/Safer-McGraw-Hill-International-
    Software-Engineering/dp/0077076400
    ▪ http://www.cse.psu.edu/~pdm12/cse597g-
    f15/readings/cse597g-embedded_systems.pdf
    ▪ https://www.blackhat.com/presentations/bh-usa-04/bh-us-04-
    grand/grand_embedded_security_US04.pdf
    

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28. CONCLUSIONS: WHY CAN'T WE
    HAVE NICE IOTHINGS
    ▪ Lack of Awareness
    ▪ Lack in Tools
    ▪ Lack in Processes
    ▪ We are not aiming for the head
    

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