Do dashes in a querystring pose a security risk for Ruby on Rails?

I got an exception in a web app I'm developing recently from a url something like:

http://domain.com/script.js?bcsi-ac-16E7C1CCF9EF6357=1C76413C00000002kmNHGZK2deV0Qz25TXynq3fMaPTrBAAAAgAAAD5tGgCEAwAACAAAAPUiAgA=

First of all - what in the world is that? From searching it sounds like maybe it's a cookie / session variable of some kind...

Second of all, the exception was about dynamic assignment of a constant. I tried a simpler url:

http://domain.开发者_开发百科com/script.js?bcsi-ac

And that gave an exception about the variable or method 'bcsi' not being defined, as if it were trying to evaluate it... WHAT!? I sure as hell hope people can't cause my Rails app to evaluate random code just by passing it to the querystring...

To provide more detail: I'm not doing anything unusual with the querystring data in the route or the controller. I just take the params and pass them into a partial as locals (admittedly not the cleanest way to do it, but simple - and that certainly shouldn't cause it to evaluate a parameter name as code?)

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OKAY! Answering my own question again. It turns out passing params in as locals to a partial DOES cause it to evaluate the parameter name as code - obviously it can't use the variable name "bcsi-ac" so it tries to evaluate it.

But the question as to whether that poses a security risk still remains... I don't seem to be able to call methods on things, or actually assign things... but maybe I just haven't tried hard enough. It would seem to me that rails should just throw an exception when passing in a locals hash that includes an invalid variable name.

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as a general rule of thumb, any time you allow strings from your url to be evaluated as code you are setting up a huge security risk in your application. you might not be able to call methods on locals as your methods exist server side and the code you are evaluating is client side, but this certainly opens your site up to XSS vulnerabilities among others...