Buffer Overflow
Attacks
A humble introduction
$whoami
• Security Enthusiast with an interest in knowing
things inside out.
DISCLAIMER
Without rwx-r-x-r
• Breaking software is ILLEGAL
• Hacking into networks is ILLEGAL
• Launching worms/virus attacks is ILLEGAL
• Governed by Indian Law - Information Technology Act, 2000.
• Section 65/66/66A…F/67 etc.
• This ppt is only for demo purposes and I am in no way responsible
for any damage done through this knowledge to self or otherwise.
What is it about?
• Buffer overflow
• Stack smashing
Don’t Expect
• Tool internals
• Tool tutorials
• Tool specifications
• Social engineering techniques
• Exploit/Payload writing
Live Attack Demo
• Real life attacks are actually REAL !
• Vulnerable Unzip Utility
• Impact
• What do you loose if you are “NAIVE”
Some useful basics?
• ESP, EIP
• Return address
• EBP
• Environment - 32bit Ubuntu 15 - ASLR disabled
and gcc - stack smashing protection - disabled.
Function call and stack
arrangement ?
• ESP, EIP
• Return address
• EBP
• funcall.c
• funCall gdb analysis
GOAL
• Control execution flow
• How ?
• Control EIP
• Where ?
• Control it in the stack (for stack smashing)
• Why ?
• User input makes it’s way to the buffers in the stack
• CALL and RET instruction auto-handle what goes in the EIP
writing exit shell code
• justQuit.c
• disassemble justQuit and figure out _exit
• exitInAsm.s
• objdump exitInAsm to get the shell code
using the exit shell code
• exitShellCode.c
• exitShellCode gdb analysis
attacker-vicim demo
• actual shell code - spawning a shell
• check in exitShellCode.c
• attack crafting concept
• default address to anything
• gdb analysis - address change and exploit
The $M ? “Who & Why”
• Several flaws in VLC
• GHOST in glibc
• getaddrinfo in glibc
• Several flaws in Apache/IIS/nginx
• All of this for FUN and PROFIT.
HUGE Thanks
• Security Tube
• Numerous blogs
• StackOverflow
• Null.co.in
• SecurityXploded
• Sans.org
• LinuxFoundation.org

Buffer Overflow Attacks

  • 1.
  • 2.
    $whoami • Security Enthusiastwith an interest in knowing things inside out.
  • 3.
    DISCLAIMER Without rwx-r-x-r • Breakingsoftware is ILLEGAL • Hacking into networks is ILLEGAL • Launching worms/virus attacks is ILLEGAL • Governed by Indian Law - Information Technology Act, 2000. • Section 65/66/66A…F/67 etc. • This ppt is only for demo purposes and I am in no way responsible for any damage done through this knowledge to self or otherwise.
  • 4.
    What is itabout? • Buffer overflow • Stack smashing
  • 5.
    Don’t Expect • Toolinternals • Tool tutorials • Tool specifications • Social engineering techniques • Exploit/Payload writing
  • 6.
    Live Attack Demo •Real life attacks are actually REAL ! • Vulnerable Unzip Utility • Impact • What do you loose if you are “NAIVE”
  • 8.
    Some useful basics? •ESP, EIP • Return address • EBP • Environment - 32bit Ubuntu 15 - ASLR disabled and gcc - stack smashing protection - disabled.
  • 9.
    Function call andstack arrangement ? • ESP, EIP • Return address • EBP • funcall.c • funCall gdb analysis
  • 10.
    GOAL • Control executionflow • How ? • Control EIP • Where ? • Control it in the stack (for stack smashing) • Why ? • User input makes it’s way to the buffers in the stack • CALL and RET instruction auto-handle what goes in the EIP
  • 11.
    writing exit shellcode • justQuit.c • disassemble justQuit and figure out _exit • exitInAsm.s • objdump exitInAsm to get the shell code
  • 12.
    using the exitshell code • exitShellCode.c • exitShellCode gdb analysis
  • 13.
    attacker-vicim demo • actualshell code - spawning a shell • check in exitShellCode.c • attack crafting concept • default address to anything • gdb analysis - address change and exploit
  • 14.
    The $M ?“Who & Why” • Several flaws in VLC • GHOST in glibc • getaddrinfo in glibc • Several flaws in Apache/IIS/nginx • All of this for FUN and PROFIT.
  • 15.
    HUGE Thanks • SecurityTube • Numerous blogs • StackOverflow • Null.co.in • SecurityXploded • Sans.org • LinuxFoundation.org