Contents and Scripts

Content Security

• Root (www) should not own contents of users
• "Are scripts allowed to run?"
• In general, all scripts run with the same permissions.
• Scripts can interfere with each other:

  All the CGI scripts will run as the same user, so they have potential to conflict with other scripts.

Key storage

TLS encryption

1. Used by most e-commerce
2. TLS applies public-key encryption
3. How to store key on a computer?

   Store in computer x--,---,--- It's owned by root, and reads in at startup before changing UIDs.

Authentication

1. Two basic types: passwords and client-side certificates.
2. Passwords should never be used without encrypting the network connection.
3. Ultimately, the client's identity is Apache UID.

Script Security

1. Allow scripts only in certain directories.
2. suEXEC runs to switch users to run.
3. suEXEC has > 20 checks before switch users, for example:
   • suEXEC is only executable by www
   • is the directory NOT writable by anyone else?

Safety pratice

1. Do not permit execution of C or C++ programs
2. Use web server access control
3. Challenge: if all scripts run with the same permission, and if local users have read-access to user content, how can a user do safe upload?
4. Script access control is difficult

Phishing:

1. trick people into sending their passwords to the wrong site.
2. People could check the site's certificate
3. Safety pratice

   Use a password manager such as 1password!