There's a sure-fire method to protect any kind of server that supports anonymous user access -- which means that this tip applies to FTP and other anonymous services, as well as Web servers that permit anonymous access. In such cases, the safest course of action is to isolate file system containers where anonymous access is permitted from containers where more stringent access controls apply. This helps avoid the famous "root level" file container access problem, where allowing anonymous users access to the root of a logical drive or disk partition somehow magically confers access to other areas in a file system. The interesting thing about this problem is that it bedevils numerous operating systems, including various versions of Linux and Unix, as well as Windows. In terms of best practices for enacting proper insulation and isolation techniques, consider the following strategies:
- is permitted.
By following these approaches you isolate anonymous users to the containers where they should be allowed access anyway. You also insulate other containers from unauthorized access through anonymous accounts. It's a win-win situation!
As always, feel free to e-mail me with feedback, comments or questions at email@example.com.
About the author
Ed Tittel is a principal at a content development company based in Austin, Texas, and the creator of the Exam Cram series. He has worked on numerous certification titles on Microsoft, Novell, CIW and Sun related topics; he's working on several security certification books in 2002 (ICSA, CISSP and more). As an expert on searchSecurity, Ed answers your questions on infosec certification and training.
This was first published in January 2002