The transactional websites and services on the cloud, have actually become the most used browsers, thanks to their portability and ease of use, with a significant increase in the development of cloud solutions, implementing digital contexts under the 4.0 web, which generated an increase of possibilities for transactions of different types. However, every time more security issues arise. Due to this problem, the computer security is a rising trend, generating new possibilities to mitigate vulnerabilities when handling the information in a transactional web site; an analysis is made of performance, weaknesses and strengths of the HSTS standard, as a security complement of the SSL/TLS protocol. Different tests scenarios are verified under a man attack in the MITM environment, to intercept or capture the traffic sent and received during web transactions. That is how we identify if the standard can prevent that intrusion, which is of vital importance for the different transactional environments actually used, such as bank entities or online purchases; vulnerabilities of the standard are verified upon making the first request to a website, which strengthens and secures transactions done from the beginning of the transaction to its ending, in an encrypted way. Browsers analyzed - Mozilla Firefox, Google Chrome and internet Explorer, under controlled corporate and personal environments; The security importance of the browser is outlined, Google Chrome being the best one in performance under an internet hacking. The other browsers present some shortcomings during the first interconnection request, during some milliseconds under the point to point model, for the initial phase of information interchange.