  A stack overflow occurs when a program or process tries to store more data in
a buffer (or stack) than it was intended to hold. If the affected program is
running with special privileges or accepts data from untrusted network hosts
(e.g. a web-server), then it is a potential security vulnerability. Overflowing
a stack, an attacker can corrupt the stack in such a way as to inject
executable code into the running program and take control of the process. This
is one of the easiest and more reliable methods for attackers to gain
unauthorized access to a computer. In this paper, we show that how stack
overflow occurs and many open source projects, such as - Linux, Git, PHP, etc.
contain such code portions in which it is possible to overflow the stacks as
well as inject malicious script to harm the normal execution of the processes.
In addition, this paper raises a concern to avoid writing such codes those are
potentially sources for stack overflow attack.
