Seo Panel 2.1.0 - Critical File Disclosure

                                                Title: Seo Panel 2.1.0 - Critical File Disclosure

Body:
Seo Panel - Critical File Disclosure
http://www.exploit-db.com/finding-0days-in-web-applications/

Versions Affected: 2.1.0 (previous versions were not checked.)

Info:
A complete open source seo control panel for managing search engine optimization of your websites.
Seo Panel is a seo tool kit includes latest hot seo tools to increase and track the performace of your websites. 

External Links:
http://www.seopanel.in/

Credits: MaXe (@InterN0T)


-:: The Advisory ::-
Seo Panel is prone to Critical File Disclosure due to download.php does not sanitize user-
input properly via the "file" GET-parameter. 
By using ....// instead of ../ to traverse through directories and by appending a %00 byte
in the end of the request it is possible to load virtually any file that the webserver user has
read access to. The PHP function which reads & returns the data from the file is: readfile($var);


Proof of Concept URL:
http://example.tld/seopanel/download.php?filesec=sitemap&filetype=text&file=....//config/sp-config.php%00.txt

Note: This attack requires a valid user though it works regardless of any privileges the user might have. 
(User registrations are enabled by default as well, making this attack possible in most scenarios.)


-:: Solution ::-
download.ctrl.php: (Line 55-62)
55	function isValidFile($fileName) {
56		$fileName = urldecode($fileName);
		// This tries to prevent directory traversal
57		$fileName = str_replace('../', '', $fileName);
58		if (preg_match('/\.xml$|\.html$|\.txt$/i', $fileName)) {
59			return $fileName;
60		}		
61		return false;
62	}
	
Suggested patch: (Line 55-62)
55	function isValidFile($fileName) {
56		$fileName = urldecode($fileName);
		// This isn't as easy to bypass anymore
57		$fileName = str_replace('..', '', $fileName); // This is changed.
58		if (preg_match('/\.xml$|\.html$|\.txt$/i', $fileName)) {
59			return $fileName;
60		}		
61		return false;
62	}


Disclosure Information:
- Vulnerabilities found and researched: 31st October 2010
- Full Disclosure ~Early November 2010