Buffer-Overflow Vulnerabilities and Attacks

[Nytro]

Buffer-Overflow Vulnerabilities and Attacks

1 Memory

In the PC architecture there are four basic read-write memory regions in a program: Stack, Data, BSS

(Block Started by Symbol), and Heap. The data, BSS, and heap areas are collectively referred to as the

”data segment”. In the tutorial titled “Memory Layout And The Stack” [1], Peter Jay Salzman described

memory layout in a great detail.

Stack:

Stack typically located in the higher parts of memory. It usually ”grows down”: from high

address to low address. Stack is used whenever a function call is made.

Data Segment

–

Data area:

contains global variables used by the program that are not initialized to zero. For

instance the string “hello world” defined by

char s[] = "hello world"

in C would

exist in the data part.

–

BSS segment:

starts at the end of the data segment and contains all global variables that are

initialized to zero. For instance a variable declared

static int i

would be contained in the

BSS segment.

–

Heap area:

begins at the end of the BSS segment and grows to larger addresses from there. The

Heap area is managed by

malloc

,

realloc

, and

free

. The Heap area is shared by all shared

libraries and dynamic load modules in a process

Download:

http://www.cis.syr.edu/~wedu/Teaching/cis643/LectureNotes_New/Buffer_Overflow.pdf