DOM Matcher¶
Format |
|
Type |
tuple |
Scope |
DOM |
It operates on the DOM loaded by the browser. When there are some data representation issues (minification, bundles, etc) it’s better to access the objects already loaded in browser’s DOM than trying to parse them with regular expressions.
This matcher is useful to extract information from objects loaded in the DOM that could contain version information under some attribute.
Example¶
A website X uses a software called yobu.
It’s loaded as part of a bundle file called assets.js
that groups every Javascript file used by the website.
Moreover, this file is obfuscated and
its content changes every time there’s a change
because of a internal building process.
No way to use a regular expression here.
However, in the browser’s Javascript console
you can see that there’s a Yobu object.
We will use a DOM matcher to extract that data.
The first element of the tuple is a check_statement written in Javascript.
What should be able to give us this statement?
It will assert that the target object exists in the DOM
to continue with version extraction.
The second element is an extractor statement written in Javascript
and it will try to access the attribute where version data lies.
Finally, we are ready with our new matcher:
from detectem.plugin import Plugin
class YobuPlugin(Plugin):
name = 'yobu'
matchers = [
{'dom': ('window.Yobu', 'version': 'window.Yobu.version')},
]
Then, when you run detectem on X,
it will detect the presence of yobu and its version 1.2.3.
Notes¶
The plugins use window as prefix because
the check statement won’t raise any error if the object doesn’t exist,
it’s easier to emulate browser in our testing suite and avoid side effects
in presence of iframes.