This document discusses buffer overflow exploits. It defines a buffer overflow as when a program overruns a buffer's boundary and overwrites adjacent memory locations. This can allow malicious code to be executed by replacing executable code. A simple C program example is provided to demonstrate this vulnerability. The document also mentions the 1988 Internet worm, which took down 10% of the Internet at the time by exploiting a buffer overflow in the finger program. Safer alternatives to vulnerable functions like gets() that cause buffer overflows are suggested.

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Buffer Overflow Exploit
Suresh Krishna

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Table of Contents
1. What is Buffer Overflow?
2. Simple Program.
3. Worm of 1988.
4. Safer side.

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What is Buffer Overflow?
Buffer Overflow is a situation where a program overruns the buffer’s
boundary and overwrites adjacent memory locations.
By sending in data designed to cause a buffer overflow, it is possible to
write into areas known to hold executable code, and replace it with
malicious code.
Can be caused by using "gets".

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Pictoral View

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Simple Program
#include <stdio.h>
#include <string.h>
void secretfunction(void)
{
puts("You have been Hacked!!");
}
void pass(void)
{
char pass[10] = "zilogic";
char buff[20];
int flag = 0;
gets(buff);
if (!strcmp(buff, pass))
flag = 1;
if (flag)
puts("Password CorrectnAuthorization
Granted!!");
else
puts("Password Wrong");
}
int main(void)
{
printf("Enter Passwordn");
pass();
return 0;
}

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Worm of 1988
The Worm is named after its creator and releaser, Robert Tappan
Morris.
The worm made use of the buffer overflow vulnerability in the finger
program.
It took down nearly 10% of the Internet of that time.

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Alternatives
1. fgets()
2. getline();

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Thank You!