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Re: Re: Why use taint

by no_slogan (Deacon)
on Mar 10, 2002 at 02:24 UTC ( #150649=note: print w/replies, xml ) Need Help??


in reply to Re: Why use taint
in thread Errors in my (simple?) CGI Script!

Only data that is used in external calls must be taint checked. For example, when a name is put in a cookie, just for fun, there's absolutely no reason to taint check it
Absolutely no reason to taint check? What if the name they give you contains "\r\n"? If you blindly copied that name into a Set-Cookie header, someone could insert arbitrary HTTP headers and HTML content into your output with a cross-site scripting attack.
you should think about encoding it, though
Encoding will solve this problem in most cases. CGI.pm automatically url-escapes cookie contents, which is yet another reason to always use it.

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Re: Re: Re: Why use taint
by Juerd (Abbot) on Mar 10, 2002 at 09:33 UTC

    As you said, encoding solves the problem. And I don't like CGI.pm, and won't use it unless forced. Not even for cookies, I'd use CGI::Cookie for that, if I have to (note: CGI::Cookies is used by CGI.pm). Or I'd just write a quick-and-dirty regex like s/(\W)/sprintf "%%%02x", ord $1/ge.

    44696420796F7520732F2F2F65206F
    7220756E7061636B3F202F6D736720
    6D6521203A29202D2D204A75657264
    

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