rpisec - 12/01/2014os security1. rpisec - 12/01/2014os security2 markus gaasedelen – b.s. computer...

OS Security 1

Security & Exploitation

Operating SystemsFall 2014

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OS Security 2

whoami

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• Markus Gaasedelen– B.S. Computer Science ’15

• Security Enthusiast– I like to hack things

• President of RPISEC– http://rpis.ec

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RPISEC

• The Computer Security Club @ RPI– http://rpis.ec

• The leading authority on campus for any and all things computer security related

• We compete in hacking competitions known as CTFs (Capture The Flag) and we’re very good at them

• We teach cool and applicable security skills at our weekly meetings– 5-7pm Fridays, DCC 318

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OS Security 4

CSAW 2014 Finals

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OS Security 5

CSAW 2014 Finals

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CSAW 2014 Awards

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WHAT IS SECURITY?let’s get rolling…

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What is Security?• Security == Hacking

– ‘politically correct’– Cyber is the buzzword

• Very technical and rewarding challenges

• Rarely taught or talked about in school ):

• Many different categories of security

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OS Security 10

Categories of Security• Cryptography• Web Security• Vulnerability Research• Binary Exploitation• Reverse Engineering• Malware Analysis• Systems Security• Embedded Hardware Hacking• Network Security• Digital Forensics• Physical Security• Pentesting• …

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OS Security 11

Categories of Security• Cryptography• Web Security• Vulnerability Research• Binary Exploitation• Reverse Engineering• Malware Analysis• Systems Security• Embedded Hardware Hacking• Network Security• Digital Forensics• Physical Security• Pentesting• …

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The kind of stuff I’ll talk about today (:

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MEMORY CORRUPTION& BINARY EXPLOITATION

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Binary Exploitation

• The simplest definition:– Leveraging bugs in an executable to cause

unintended, controlled actions by an attacker

• Requires intimate knowledge of the language, compiler, and the machine

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Bugs Are Everywhere

• C is a ‘low level’ language– Compiles straight to machine code (x86, ARM, etc)• Very fast

– Very fine control over the machine and memory• It’s like driving a manual!

– Easy to do stupid things

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The Unexciting Languages

• Binary exploitation isn’t really a thing for managed or scripting languages– C#, .NET, JavaScript, Lua, Python, etc

• Slower, automate lots of stuff for you– Driving an automatic

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WELCOME TO THE WARZONElet’s dive right in and try breaking some stuff

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warzone.rpis.ecssh username/password

intro01:intro01

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Getting Started / Tips

• cd /levels• ./intro01– AAAAAAAAAAAAAAAAA

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

• python –c ‘print “A”*20’• gdb ./intro01– run

• In GDB:– Info functions– Info registers

• i r

– disassemble <function>• disas main

– breakpoint <function>• b main

– breakpoint * <address>• b * 0x08048455

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Stack Overview• The stack is a region of

memory for a program to maintain function variables and stuff during execution

• This is main()’s stack ------->

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Understanding the Stack

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Understanding the Stack

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Corrupting the Stack

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PWNING the Stack

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Endianess

• Endianess – How data is stored in memory

• Modern computers are generally little endian– ‘little end in’

• Endianess can be confusing, and I don’t want to get into the details– 0x41424344 stored as 0x44, 0x43, 0x42, 0x41– 0xdeadbeef stored as 0xef, 0xbe, 0xad, 0xde

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Intro01 Exploit

(python -c 'print "A"*64 + "\xef\xbe\xad\xde"'; cat) | ./intro01

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UNDERSTANDING CONTROL FLOWBend it like Beckham

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Example ELF / EXE in Memory

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Runtime Memory

Stack

ELF Executable

.text segment

.data segment

Heap

0x00000000 – Start of memory

0xFFFFFFFF – End of memory

0x08048000 – Start of .text Segment

0xbfff0000 – Top of stack

Libraries (libc)

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.text segment

Example ELF / EXE in Memory

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Runtime Memory

Stack

Heap

Executable code

Libraries (libc)

ELF Executable

.text segment

.data segment

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.text segment

Example ELF / EXE in Memory

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Runtime Memory

Stack

Heap

Executable code

Libraries (libc)

ELF Executable

.text segment

.data segment

EIP

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.text segment

Example ELF / EXE in Memory

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Runtime Memory

Stack

Heap

Executable code

Libraries (libc)

ELF Executable

.text segment

.data segmentEIP

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.text segment

Example ELF / EXE in Memory

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Runtime Memory

Stack

Heap

Executable code

Libraries (libc)

ELF Executable

.text segment

.data segment EIP

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.text segment

Example ELF / EXE in Memory

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Runtime Memory

Stack

Heap

Executable code

Libraries (libc)

ELF Executable

.text segment

.data segment EIP

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.text segment

Example ELF / EXE in Memory

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Runtime Memory

Stack

Heap

Executable code

Libraries (libc)

ELF Executable

.text segment

.data segmentEIP

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.text segment

Example ELF / EXE in Memory

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Runtime Memory

Stack

Heap

Executable code

Libraries (libc)

ELF Executable

.text segment

.data segment

EIP

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.text segment

Example ELF / EXE in Memory

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Runtime Memory

Stack

Heap

Libraries (libc)

ELF Executable

.text segment

.data segment

EIP

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.text segment

Example ELF / EXE in Memory

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Runtime Memory

Stack

Heap

Libraries (libc)

ELF Executable

.text segment

.data segment

EIP

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.text segment

Example ELF / EXE in Memory

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Runtime Memory

Stack

Heap

Executable code

Libraries (libc)

ELF Executable

.text segment

.data segment

EIP

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.text segment

Example ELF / EXE in Memory

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Runtime Memory

Stack

Heap

Libraries (libc)

ELF Executable

.text segment

.data segment

EIP

OS Security 40

How Calling Works

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EIP

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How Calling Works

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EIP

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How Calling Works

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EIP

…

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How Calling Works

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EIP

…

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How Calling Works

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EIP

…

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How Calling Works

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EIP …

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Returning

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…

EIP

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Returning

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…

EIP

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Returning

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…

EIP

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Returning

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…

EIP

OS Security 50

Returning

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…

EIP

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OWNING CONTROL FLOWNow that you know how it works …

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Stack Smashing

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…EIP

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Stack Smashing

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…EIP

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Stack Smashing

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…

EIP

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Returning

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…

EIP

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Returning home

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…

EIP SEGFAULT0x41414141

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OS Security 58

“If your program simply segfaulted, consider yourself lucky.”

-Chuck Stewart

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OS Security 59

Redirecting Control Flow

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…

EIP

Overwrite witha code address

OS Security 60

warzone.rpis.ecSSH in as intro02

use the password you got from solving intro01

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Modern Protections

• Address Space Layout Randomization (ASLR)• Data Execution Prevention (DEP)• Stack Cookies (Canaries)• Stack Rearrangement• Read Only Relocation (RELRO)• FORTIFY_SOURCE• These only make things harder, not impossible– Take MBE if you want to know more about these

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OS Security 63

LETS TRY SOMETHING REAL(ER)Those were only educational challenges

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OS Security 64

CHATSERVER V3Courtesy of Goldschmidt

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ChatServer V3

• From NetProg (CSCI-4220)• 32bit Linux Exploitation• Vulnerable to a stack smash– Compiler’s stack cookies save the day

• I’ll be demoing without cookies, not exploitable otherwise ):

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CHATSERVER V3 – DEMOCourtesy of Goldschmidt

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CSAW 2014 LINKS.EXEWindows 8.1 Exploitation (x64)

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links.exe

• Challenge from the CSAW 2014 CTF Finals• 64bit Exploitation on Windows 8.1• Basically all protections are on by default• No source, lots of reversing :0

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reversing is tedious

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OS Security 70

CSAW 2014 LINKS.EXE - DEMOWindows 8.1 Exploitation (x64)

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CSAW 2014 Finals

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Wrapping up Binary Exploitation

• You might consider yourself a rockstar programmer, but you probably know nothing about secure coding practices or the implications of your mistakes

• Compilers go out of their way to prevent your bugs from causing catastrophic failure

• Because your program doesn’t appear to segfault or crash, doesn’t mean it is bug free or without vulnerabilities

• Binary exploitation is nothing like standard software development - I truly think of it as an art

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JOB OPPORTUNITIESwelcome to the real world

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…so…many…jobs…

• Typical titles / positions– Information Security Analyst / Engineer– Security Software Engineer– Vulnerability Research Engineer– Web Application Security Engineer– Computer Network Operations– Threat & Incident Response Engineer– Product Security Reverse Engineer– Malware Analyst / Reverse Engineer– …

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OS Security 75

Entering the Job Market

• There are so few qualified security individuals, companies are totally starved ):

• Skilled in security & have a B.S. in CS?– Government, Contractors, FFRDCs• $70k – $90k+

– Private / Commercial• $100k – ??

• Anything less and you’re missing out

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MODERN BINARY EXPLOITATIONComing Soon - Spring 2015

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Modern Binary Exploitation

• An official class developed by RPISEC• http://rpis.ec/binexp• Class cap is raised to 50!– Thank Goldschmidt & Stewart for getting us an

awesome room that seats 50+, Walker 5113– General registration re-opens December 8th

• Tuesday/Friday 2-4pm, Spring 2015• DON’T MISS THIS! – ZERO guarantee it’ll ever be offered again

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Questions?

• gaasem@rpi.edu• security.cs.rpi.edu/~gaasem• @gaasedelen• irc.rpis.ec 6667

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