Definition

Have you ever thought of a buffer overflow attack ? It occurs through careless programming and due to patchy nature of the programs. Many C programs have buffer overflow vulnerabilities because the C language lacks array bounds checking, and the culture of C programmers encourages a performance-oriented style that avoids error checking where possible. Eg: gets and strcpy ( no bounds checking ). This paper presents a systematic solution to the persistent problem of buffer overflow attacks. Buffer overflow attack gained notoriety in 1988 as part of the Morris Worm
incident on the Internet. These problems are probably the result of careless programming, and could be corrected
by elementary testing or code reviews along the way.

THE ATTACK :- A (malicious) user finds the vulnerability in a highly privileged program and someone else implements a patch to that particular attack, on that privileged program. Fixes to buffer overflow attacks attempt to solve the problem at the source (the vulnerable program) instead of at the destination (the stack that is being overflowed).

StackGuard :- It is a simple compiler extension that limits the amount of damage that a buffer overflow attack can inflict on a program. The paper discusses the various intricacies to the problem and the implementation details of the Compiler extension 'Stack Guard '.

Stack Smashing Attack :- Buffer overflow attacks exploit a lack of bounds checking on the size of input being stored in a buffer array. The most common data structure to corrupt in this fashion is the stack, called a ``stack smashing attack'' .

StackGuard For Network Access :- The paper also discusses the impacts on network access to the 'Buffer Overflow Attack'.

StackGuard prevents changes to active return addresses by either :-
1. Detecting the change of the return address before the function returns, or
2. Completely preventing the write to the return address. MemGuard is a tool developed
to help debug optimistic specializations by locating code statements that change quasi-invariant
values.

STACKGUARD OVERHEAD
" Canary StackGuard Overhead
" MemGuard StackGuard Overhead
" StackGuard Macrobenchmarks

The paper presents the issues and their implications on the 'IT APPLICATIONS' and discusses the solutions through implementation details of 'Stack Guard'.