I am managing an application that gets requests through API. Some of the requests are having invalid characters. The Request URL/API looks like:
/up/100.php?f=0&t=n\x01\x02&...
These \x01\x02 causing Apache2 to throw 400 errors.
I can't change/alter the URL. I need to fix my apache to accept and process that URL. I tried mod_rewrite but couldn't found the correct one.
Any Help?
Update and Solution
Now, I found that the request is really a malfunctioned URL. So, what I did to solve the problem? I've created a custom error handling page to sanitize the URL and make it work.
Try the following at the top of your .htaccess file:
RewriteEngine On
RewriteCond %{QUERY_STRING} (.*)\\x01\\x02(.*)
RewriteRule ^up\.php$ /$0?%1%2 [R,L]
The double backslash in the CondPattern is necessary to match a single backslash in the query string, since the backslash is used as the escape character in PCRE regex.
The %1 and %2 backreferences match the characters either side of the sequence you want to remove. $0 is just a backreference to the matched URL-path (saves repetition).
HOWEVER, a request of the form /up.php?f=0&t=n\x01\x02&... would not ordinarily trigger a 400 response. The character sequence \x01\x02 in the URL is just a literal character sequence: \, x, 0, 1, etc. (it's not an encoded character in this context).
So, if you are getting a 400 response, it's possible that something else (a mod_security rule perhaps?) is triggering this response - which maybe out of your control?