buffer overflow
buffer overflow
can anyone explain what's a buffer overflow attack!?!? 
Well, let's say you have a buffer that is the according:
That is an example of how buffer overflow occurs, basically it is when you try to make the buffer hold that it's size.
Code:
char Buffer[5]; strcpy(Buffer, "More than 5 chars is a buffer overflow");
Since the above explanation sucks...
A buffer overflow attempts to write data outside of a specific memory region allocated.
It is commonly used as an attack ( or exploit ) to allow a program to execute things that it isn't supposed to normally execute.
Consider the following C code:
What happens if we pass the number "99999" to it?
A buffer overflow occurs. Why?
Let's look at it:
- 5 characters of '9'
- 1 null terminator
But the buffer is only 5 bytes in size. So what happens? It overwrites the adjacent memory.
Assume the memory looks like this:
Assuming we write the memory with the above "99999" integer passed, it will now look like this:
As you can see, the highest byte of "anotherVariable" gets overwritten with the null terminator ( 0 ).
That's essentially what static memory buffer overflows are.
Stack based buffer overflows occur when the same thing above happens, but on the stack.
This can be used to redirect your RIP/EIP register to perform code execution that shouldn't normally happen.
A buffer overflow attempts to write data outside of a specific memory region allocated.
It is commonly used as an attack ( or exploit ) to allow a program to execute things that it isn't supposed to normally execute.
Consider the following C code:
Code:
const char* myFunc( int myNum ){
static char num2Str[5];
sprintf( num2Str, "%i", myNum );
return num2Str;
}
A buffer overflow occurs. Why?
Let's look at it:
- 5 characters of '9'
- 1 null terminator
But the buffer is only 5 bytes in size. So what happens? It overwrites the adjacent memory.
Assume the memory looks like this:
Code:
num2Str anotherVariable xxxxx xxxxxxxxxxxxx
Code:
num2Str anotherVariable 99999 0xxxxxxxxxxx
That's essentially what static memory buffer overflows are.
Stack based buffer overflows occur when the same thing above happens, but on the stack.
This can be used to redirect your RIP/EIP register to perform code execution that shouldn't normally happen.
Originally Posted by Hitokiri~
