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Third party extensions

Challenger handles three types of third-party extensions, Challenger modules, CGI-scripts and Java servlets. With any extension you install on your web server you must take the security issues into account. You must trust the programmer of the extension to have written it with security in mind. The main problem is how user input is handled, what will happen if the extension gets a megabyte of machine code instead of the line of text it expected.

Challenger modules
Challenger modules are the preferred way of extending Roxen Challenger. Modules become part of Challenger and their functionality can be used by other modules. In effect, modules have to do less and provide more. A module does not have to do as much, which means that it will be shorter and the risk of bugs will be reduced.

Challenger takes care of a lot of potential security issues by itself. For example, it is impossible to make a buffer overrun bug that enables an attacker to execute machine code. But, this does not mean that the programmer of a Challenger module can ignore security considerations. A Challenger module will always be run with the same permission as the Challenger server and any security hazard in the module will affect the whole server. Therefore, we recommend you only run modules distributed by reputable web sites.

Most third-party extensions for web servers are available as CGI-scripts, because they will work on all web servers. In Challenger, the CGI executable support module handles CGI-scripts.

When writing CGI-scripts, the programmer has to take care of all security issues herself. This is currently not a skill all programmers possess, it has only been an issue for a little while. Therefore, CGI-scripts are a major cause of security hazards today.

Challenger has the option of running CGI-scripts as a low privilege user. Use this to make sure that the CGI-script can cause as little damage as possible. Only download CGI-scripts from web sites that show that they treat security issues seriously.

Java servlets
Java servlets are extensions that share many of the good properties of Challenger modules. They are run within the web server, and therefore uses less resources CGI scripts. They are implemented using a interpreted object-oriented language, thereby making it harder to make mistakes that affect the security of the server.