Fire and motion

Internet Security


Beware: I am a real neophyte when it comes to internet security. Having said that, I couldn't have fared any worse than Sony Pictures. They lost 1,000,000 plain-text passwords when a SQL injection vulnerability was discovered. I've been protecting against that attack since 2005. (At the part, "Is the password secure?" is where I say the passwords aren't stored in plain text. SQL injections have been the subject of security jokes for a long time, too. Ah, Little Bobby Tables.)

There have been and continue to be large breaches of personal data on the internet. Nathan Yau shares an infographic of the largest data breaches of all time.

My immediate family and I need a way to keep each other up to date with our changed account info and ID numbers. We need a solution that meets the following usability criteria:

  • Accessible anywhere, from any device. It has to be practically just one click away.
  • Trivial, memorable URL. We may be typing it directly into the URL bar.
  • Always up-to-date. Any change made from anywhere is accessible immediately from any other client.

If it's not that easy to use, it won't be used, and there'd be no point in making it. On the other hand, it has to have the following security criteria:

  • Accessible anywhere, from any device. It has to be secure even over a public wifi network.
  • Secure from remote client attacks. It has to handle attacks over the internet.
  • Secure from local attacks. It has protect against disgruntled hosting company employees.

With all that in mind, I've decided to roll my own information vault. Here are some goals and notes from that venture:

Be A Low Value Target

My first line of defense is that my information vault is just for me and my family. This'll never store enough data of real value to make it a target for the economics of it. I might get attacked, but it'd only be for the idle challenge of it.

Block Direct Access of Data Files

Move data files off the server, even though they're encrypted, or into directories tightly controlled by permission settings and .htaccess instructions. Test both attacks. If your encrypted files can fall into your attacker's hands, they can try a local brute force attack. (More on that below.)

Use HTTP Secure

For any data that is accessible, use HTTPS. This is the first line of defense if you want your data accessible over a public wifi network.

Unique and Long Master Password

Force your users to use a long random, impossible-to-guess master password. Prevent any sort of social attack: No names, dates, or places. In my case, since I'm the creator of the tool, I can do this.

Use a Hard-To-Compute Hash for the Master Password

Related: Do not store the master password anywhere. And the salted hash you use for it should be secure. Refer to this wikipedia article on cryptographic hash functions to see relative weaknesses of the functions. I've considered throwing in with a hashing algorithm that adapts to faster hardware to frustrate brute-force attacks.

Don't Store any Data in Plain Text

This is a defense against a local attack from someone who can obtain file-level access, like a company employee with admin access.

Sony Pictures stored private data in plain text format, and thus enabled this interesting analysis of passwords in the Sony Pictures security breach. Consider your encryption algorithm carefully. I used AES, but am keeping my options open. I can change my backend at any time.

Limit Cookie Scope

Limit your HTTPS cookie scope with morsels like max-age, httponly, domain, path and secure morsels.

While you're at it, it doesn't hurt to salt cookie and session data with an identifier associated with the request. In Python you could use os.environ['REMOTE_ADDR'].

Protect Against Javascript / SQL Injection

Know what kinds of attacks can be performed. Encode characters that have special meaning for the languages you use, like the quotes characters, <, >, and &, among others. In Python, the bare minimum you'd use is cgi.escape for that, but you'd want to use other functions depending on where/how the data is travelling or being displayed.

Analyze and Act Upon Suspicious Activity

It's not enough that your server is passively logging each access. Your site needs to analyze recent activity and take action (like email you or ban certain origins) when preset triggers are tripped.

Keep Protecting

Security is not a product, but a process." --Bruce Schneier, author of "Applied Cryptography"

This blog entry may have already has fallen out-of-date with new measures I've taken to protect our information vault.

If I'm missing a vector of attack, or you have some practical advice for me, I'd appreciate hearing from you.

Photo by Lawrence Lew, O.P. / CC BY-NC-ND 2.0

One comment on "Internet Security"

  1. David on December 13th, 2011

    Just testing the comment and gravatar features now that I've updated the blog to Habari 0.8. I'll probably delete this comment.

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