  Software has become an integral part of everyday life. Everyday, millions of
people perform transaction through internet, ATM, mobile phone, they send email
and Egreetings, and use word processing and spreadsheet for various purpose.
People use software bearing in mind that it is reliable and can be trust upon
and the operation they perform is secured. Now, if these software have
exploitable security hole then how can they be safe for use. Security brings
value to software in terms of peoples trust. The value provided by secure
software is of vital importance because many critical functions are entirely
dependent on the software. That is why security is a serious topic which should
be given proper attention during the entire SDLC, right from the beginning. For
the proper implementation of security in the software, twenty one security
rules are proposed in this paper along with validation results. It is found
that by applying these rules as per given implementation mechanism, most of the
vulnerabilities are eliminated in the software and a more secure software can
be built.
