Full Disclosure mailing list archives
Re: Apache Illegal Request Handling Possible XSS Vulnerability
From: "Michal Majchrowicz" <m.majchrowicz () gmail com>
Date: Tue, 24 Apr 2007 11:44:14 +0200
In this case I agree this is a solution. If Apache wouldn't accept any 'separators' then XSS (and other stuff) wouldn't be possible at all. Is there anywhere described which chars can be used in protocol "field"? Regards Michal. On 4/24/07, Richard Moore <rich () westpoint ltd uk> wrote:
Michal Majchrowicz wrote:Okay so let's assume that there cany "anything" as the request. But there has to be something that handles this request? If there is no "handler" for request "<script>" Apache should return error page. And what about protocol version? You didn't answer this question. Regards Michal.The handler here is your script - there's no way for apache to know what your script does. It is the responsibility of the script to raise an error in this case. To be precise the HTTP specification (RFC 2616) says a method is: Method = "OPTIONS" ; Section 9.2 | "GET" ; Section 9.3 | "HEAD" ; Section 9.4 | "POST" ; Section 9.5 | "PUT" ; Section 9.6 | "DELETE" ; Section 9.7 | "TRACE" ; Section 9.8 | "CONNECT" ; Section 9.9 | extension-method extension-method = token Now, token is defined by these productions: token = 1*<any CHAR except CTLs or separators> CHAR = <any US-ASCII character (octets 0 - 127)> separators = "(" | ")" | "<" | ">" | "@" | "," | ";" | ":" | "\" | <"> | "/" | "[" | "]" | "?" | "=" | "{" | "}" | SP | HT CTL = <any US-ASCII control character (octets 0 - 31) and DEL (127)> So that implies that Apache is being slightly lax in passing arbitrary content. However, there is no fixed list of valid methods as you can define your own as an extension-method. This is used by a number of protocols. Apache should probably raise an error if the method contains characters outside these defined productions. Cheers Rich.On 4/24/07, Richard Moore <rich () westpoint ltd uk> wrote:Michal Majchrowicz wrote:Hi. I think that server should have a list of valid requests. In fact Apache warns you sometimes that valid requests are: "GET/POST/TRACE/OPTIONS". The solution that it just accepts everything as request and protocol makes no sense. What kind of protocol isIt makes lots of sense as I said - protocols like WebDAV are layered on top of HTTP and are implemented in apache using the exact same API as PHP uses. They need to add methods like PROPFIND etc. Unless they are required to define the exact set of verbs supported by every page then there's no way to define a fixed list. I do however agree that it could be restricted to something like [A-Z0-9]+ as I said. Cheers Rich."<script>"? Regards Michal. On 4/24/07, Richard Moore <rich () westpoint ltd uk> wrote:Michal Majchrowicz wrote:Hi. I think now we can classify this as flaw in Apache. It accepts requests that simply make no sense. Take a look at this example: <script>alert(document.cookie);</script> /test.php <script>alert(document.cookie);</script> In some circumstances it may cause XSS vulnerability: <?php echo $_SERVER['REQUEST_METHOD']; echo $_SERVER['SERVER_PROTOCOL']; ?>As Kradorex Xeron said, that's a flaw in the script. Apache needs to let arbitrary verbs through to the PHP (or other server extension) otherwise tools like webdav that require additional verbs could not be implemented. It is possibly arguable that it should restrict the verbs to a single alphanumeric string, but it certainly can't be counted on to be just GET/POST etc. Cheers Rich.I am now investigating other possible attacks. Regards Michal Majchrowicz. _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.grok.org.uk/full-disclosure-charter.html Hosted and sponsored by Secunia - http://secunia.com/-- Richard Moore, Principal Software Engineer, Westpoint Ltd, Albion Wharf, 19 Albion Street, Manchester, M1 5LN, England Tel: +44 161 237 1028 Fax: +44 161 237 1031-- Richard Moore, Principal Software Engineer, Westpoint Ltd, Albion Wharf, 19 Albion Street, Manchester, M1 5LN, England Tel: +44 161 237 1028 Fax: +44 161 237 1031-- Richard Moore, Principal Software Engineer, Westpoint Ltd, Albion Wharf, 19 Albion Street, Manchester, M1 5LN, England Tel: +44 161 237 1028 Fax: +44 161 237 1031
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Current thread:
- Apache Illegal Request Handling Possible XSS Vulnerability Michal Majchrowicz (Apr 24)
- Re: Apache Illegal Request Handling Possible XSS Vulnerability Richard Moore (Apr 24)
- Re: Apache Illegal Request Handling Possible XSS Vulnerability Michal Majchrowicz (Apr 24)
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- Re: Apache Illegal Request Handling Possible XSS Vulnerability Michal Majchrowicz (Apr 24)
- Re: Apache Illegal Request Handling Possible XSS Vulnerability Richard Moore (Apr 24)
- Re: Apache Illegal Request Handling Possible XSS Vulnerability Michal Majchrowicz (Apr 24)
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- Re: Apache Illegal Request Handling Possible XSS Vulnerability KJKHyperion (Apr 24)
- Re: Apache Illegal Request Handling Possible XSS Vulnerability Richard Moore (Apr 24)
- Re: Apache Illegal Request Handling Possible XSS Vulnerability Michal Majchrowicz (Apr 24)
- Re: Apache Illegal Request Handling Possible XSS Vulnerability Richard Moore (Apr 24)
- Re: Apache Illegal Request Handling Possible XSS Vulnerability Kradorex Xeron (Apr 24)
- Re: Apache Illegal Request Handling Possible XSS Vulnerability Kradorex Xeron (Apr 24)
- Re: Apache Illegal Request Handling Possible XSS Vulnerability Kradorex Xeron (Apr 24)