Get a solid Service Level Agreement (SLA). An SLA requires that the vendor provide a specified level of system reliability. A good vendor will strive for performance that meets Six Sigma levels of service quality (e.g., 99.9997% of security patches made within a set number of hours, not days, after public disclosure).
SaaS brings with it a unique set of challenges for those responsible for security. Barmak Meftah, senior vice president at Fortify Software, says the most important shift is looking at your software vendor not as a product company, but rather as a service provider in a guest commentary over at our CTO Edge site. Sound vendor management practices dictate that any third-party software is at least as secure as in-house packages, Meftah advises.
We've taken his checklist of steps to ensure that a SaaS vendor's solution is secure and listed them in this handy slideshow, but do be sure to check out Meftah's full column. His final piece of advice? Remember that software is secure only when it’s built that way.