Re: [mod-security-users] checking single parameter value

[joe b. <joe...@ya...>]

Thank you Alex for the explanation;
   
  But then why did the = sign pass in the hash value if the rule is saying only allow multiple 0-9 a-z A-Z characters?

"Alex V." <ale...@ss...> wrote:
  On Jeu 13 avril 2006 14:31, joe barbish a écrit :
> Thanks Alex
> That worked as shown by these debug log messages
>
> Checking signature "^/mls_verifyemail.php" at REQUEST_URI
> Checking against "/mls_verifyemail.php?hash=YmFyYmlzaDI="
> Signature check returned 403
> Chained rule with match, continue in the loop
> Checking signature "^[0-9a-zA-Z]*" at ARG(hash)
> Checking against "YmFyYmlzaDI="
> Signature check returned -1
> Access allowed based on pattern match "^[0-9a-zA-Z]*" at CUSTOM
> Allow request to pass through
>
> But I am concerned by the asterisk at the end of "^[0-9a-zA-Z]*"
> Is that a wildcard meaning anything else is accepted like the = in the
> hash value?
>
> The hash value is created using this
> $hash = base64_encode($logonid);
>
> Does base64_encode create any other special characters?
>
> Wouldn't "^[0-9a-zA-Z=]" be more secure?
>

No... It's not a security case, but it mean (as for all regexp), that you
can have only [0-9a-zA-Z] chars, but more than one !!

Here are examples :
^[0-9a-zA-Z] -> accept 1 char in this list (0-9a-zA-Z)
^[0-9a-zA-Z]? -> accept blank or 1 char in this list (0-9a-zA-Z)
^[0-9a-zA-Z]+ -> accept 1 or more char(s) in this list (0-9a-zA-Z)
^[0-9a-zA-Z]* -> accept 0 or more chars in this list (0-9a-zA-Z)






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