Transcript RPISEC lecture notes - Computer Science Department

Security & Exploitation
Operating Systems
Fall 2014
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whoami
• 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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CSAW 2014 Finals
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CSAW 2014 Finals
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CSAW 2014 Awards
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let’s get rolling…
WHAT IS SECURITY?
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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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Categories of Security
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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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Categories of Security
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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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let’s dive right in and try breaking some stuff
WELCOME TO THE WARZONE
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warzone.rpis.ec
ssh username/password
intro01:intro01
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Getting Started / Tips
• cd /levels
• ./intro01
• In GDB:
– AAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAA
AAAAAAAA
• python –c ‘print “A”*20’
• gdb ./intro01
– run
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– Info functions
– Info registers
• ir
– 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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------->
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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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Bend it like Beckham
UNDERSTANDING CONTROL FLOW
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Example ELF / EXE in Memory
Runtime Memory
0x00000000 – Start of memory
Libraries (libc)
ELF Executable
0x08048000 – Start of .text Segment
.text segment
.data segment
Heap
Stack
0xbfff0000 – Top of stack
0xFFFFFFFF – End of memory
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Example ELF / EXE in Memory
Runtime Memory
Libraries (libc)
ELF Executable
.text segment
Executable code
.text segment
.data segment
Heap
Stack
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Example ELF / EXE in Memory
Runtime Memory
Libraries (libc)
ELF Executable
.text segment
Executable code
EIP
.text segment
.data segment
Heap
Stack
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Example ELF / EXE in Memory
Runtime Memory
Libraries (libc)
ELF Executable
.text segment
Executable code
EIP
.data segment
.text segment
Heap
Stack
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Example ELF / EXE in Memory
Runtime Memory
Libraries (libc)
ELF Executable
.text segment
.data segment
Executable code
EIP
.text segment
Heap
Stack
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Example ELF / EXE in Memory
Runtime Memory
Libraries (libc)
ELF Executable
.text segment
.data segment
Executable code
.text segment
EIP
Heap
Stack
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Example ELF / EXE in Memory
Runtime Memory
Libraries (libc)
ELF Executable
.text segment
Executable code
.text segment
.data segment
EIP
Heap
Stack
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Example ELF / EXE in Memory
Runtime Memory
Libraries (libc)
ELF Executable
.text segment
Executable code
.text segment
.data segment
EIP
Heap
Stack
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Example ELF / EXE in Memory
Runtime Memory
Libraries (libc)
EIP
ELF Executable
.text segment
.text segment
.data segment
Heap
Stack
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Example ELF / EXE in Memory
Runtime Memory
Libraries (libc)
ELF Executable
.text segment
.text segment
.data segment
EIP
Heap
Stack
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Example ELF / EXE in Memory
Runtime Memory
Libraries (libc)
ELF Executable
.text segment
Executable code
.text segment
.data segment
EIP
Heap
Stack
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Example ELF / EXE in Memory
Runtime Memory
Libraries (libc)
EIP
ELF Executable
.text segment
.text segment
.data segment
Heap
Stack
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How Calling Works
EIP
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How Calling Works
EIP
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How Calling Works
EIP
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How Calling Works
EIP
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How Calling Works
EIP
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How Calling Works
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
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Returning
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EIP
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Now that you know how it works …
OWNING CONTROL FLOW
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Stack Smashing
EIP
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Stack Smashing
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
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SEGFAULT
0x41414141
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“If your program simply segfaulted,
consider yourself lucky.”
-Chuck Stewart
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Redirecting Control Flow
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Overwrite with
a code address
EIP
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warzone.rpis.ec
SSH in as intro02
use the password you got from solving intro01
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Modern Protections
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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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Those were only educational challenges
LETS TRY SOMETHING REAL(ER)
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Courtesy of Goldschmidt
CHATSERVER V3
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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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Courtesy of Goldschmidt
CHATSERVER V3 – DEMO
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Windows 8.1 Exploitation (x64)
CSAW 2014 LINKS.EXE
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links.exe
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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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Windows 8.1 Exploitation (x64)
CSAW 2014 LINKS.EXE - DEMO
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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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welcome to the real world
JOB OPPORTUNITIES
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…so…many…jobs…
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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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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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Coming Soon - Spring 2015
MODERN BINARY EXPLOITATION
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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?
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[email protected]
security.cs.rpi.edu/~gaasem
@gaasedelen
irc.rpis.ec 6667
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