Application security issues to consider

Question

I am working on the design of a high security application (involving financial information, personal information etc). I need to identify what security measures (application level) will be implemented. The application will involve sending data to and from a database, user login, import export to csv, txt files, and print function.

What security features do I need to consider for such an application. (SQL injection for starters) ?

Also, if I want to ensure that a legit user is moving from page to page, do I have to check on every page if (UserLogin.IsValid) etc? That might require a few too many server hits I am guessing.

Answer 1

The first thing to do is build a threat model. Only once you understand:

• what are the resources being protected?
• what are the vulnerabilities of those resources that expose them to attack?
• what are the motivations of attackers?
• what threats do the attackers pose?

can you reasonably start to craft a solution. For example, if the resource is my television, the vulnerability is an open window, the attackers have financial gain as a motive, and the threat they pose is the theft of my television, then I can start to craft a solution.

Consider the multi-pronged solution that becomes apparent once you have a list of resources, vulnerabilities, motivations and threats. I can:

• Make the vulnerability harder to exploit: close and lock the window, get an alarm, get unbreakable glass
• Make the resource less valuable to the attacker, thereby demotivating them: buy a cheaper, heavier television
• Make the loss of the resource less costly to me: buy insurance
• And so on.

Notice that a good solution has defense in depth. Don't just stop there. Look for more vulnerabilities. Look for more ways to demotivate attackers. Look for more ways to lower the cost of a successful attack. But all of this depends on having an accurate threat model, so do that first.

Here's some resources to get you started:

http://www.microsoft.com/security/sdl/getstarted/threatmodeling.aspx