Firebug is a browser add-on that allows us to analyze the inner components of a web page, such as table elements, cascading style sheets (CSS) classes, frames, and so on. It also has the ability to show us DOM objects, error codes, and request-response communication between the browser and server.
In the previous recipe, we saw how to look into a web page's HTML source code and found a hidden input field that established some default values for the maximum size of a file. In this recipe, we will see how to use the browser's debugging extensions, in this particular case, Firebug for Firefox or OWASP-Mantra.
type="hidden"
parameter on the first input of the form; double-click on hidden
.hidden
by text
and hit Enter.30000
of the parameter value.500000
.500000
as the value. We have just changed the file size limit and added a form field to change it.Once a web page is received by the browser, all its elements can be modified to alter the way the browser interprets it. If the page is reloaded, the version generated by the server is shown again.
Firebug allows us to modify almost every aspect of how the page is shown in the browser; so, if there is a control-established client-side, we can manipulate it with this tool.
Firebug is not only a tool to unhide inputs or change values, it also has some other very useful tools:
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