Potential Report of XSS in gmodules.com, CWE-79, CAPEC-86, Cross Site Scripting

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Report generated by XSS.CX at Sun Mar 06 10:18:44 CST 2011.

The DORK Report

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1. Cross-site scripting (reflected)

2. Cross-domain Referer leakage

3. Robots.txt file

4. Content type incorrectly stated


1. Cross-site scripting (reflected)  next

Summary

Severity:   High
Confidence:   Certain
Host:   http://www.ig.gmodules.com
Path:   /gadgets/ifr

Issue detail

The value of the url request parameter is copied into a JavaScript rest-of-line comment. The payload af6df%0aalert(1)//70d7901fece was submitted in the url parameter. This input was echoed as af6df
alert(1)//70d7901fece in the application's response.

This proof-of-concept attack demonstrates that it is possible to inject arbitrary JavaScript into the application's response.

Remediation detail

Echoing user-controllable data within a script context is inherently dangerous and can make XSS attacks difficult to prevent. If at all possible, the application should avoid echoing user data within this context.

Issue background

Reflected cross-site scripting vulnerabilities arise when data is copied from a request and echoed into the application's immediate response in an unsafe way. An attacker can use the vulnerability to construct a request which, if issued by another application user, will cause JavaScript code supplied by the attacker to execute within the user's browser in the context of that user's session with the application.

The attacker-supplied code can perform a wide variety of actions, such as stealing the victim's session token or login credentials, performing arbitrary actions on the victim's behalf, and logging their keystrokes.

Users can be induced to issue the attacker's crafted request in various ways. For example, the attacker can send a victim a link containing a malicious URL in an email or instant message. They can submit the link to popular web sites that allow content authoring, for example in blog comments. And they can create an innocuous looking web site which causes anyone viewing it to make arbitrary cross-domain requests to the vulnerable application (using either the GET or the POST method).

The security impact of cross-site scripting vulnerabilities is dependent upon the nature of the vulnerable application, the kinds of data and functionality which it contains, and the other applications which belong to the same domain and organisation. If the application is used only to display non-sensitive public content, with no authentication or access control functionality, then a cross-site scripting flaw may be considered low risk. However, if the same application resides on a domain which can access cookies for other more security-critical applications, then the vulnerability could be used to attack those other applications, and so may be considered high risk. Similarly, if the organisation which owns the application is a likely target for phishing attacks, then the vulnerability could be leveraged to lend credibility to such attacks, by injecting Trojan functionality into the vulnerable application, and exploiting users' trust in the organisation in order to capture credentials for other applications which it owns. In many kinds of application, such as those providing online banking functionality, cross-site scripting should always be considered high risk.

Remediation background

In most situations where user-controllable data is copied into application responses, cross-site scripting attacks can be prevented using two layers of defenses:In cases where the application's functionality allows users to author content using a restricted subset of HTML tags and attributes (for example, blog comments which allow limited formatting and linking), it is necessary to parse the supplied HTML to validate that it does not use any dangerous syntax; this is a non-trivial task.

Request

GET /gadgets/ifr?exp_rpc_js=1&exp_track_js=1&url=http%3A%2F%2Fwww.gstatic.com%2Fig%2Fmodules%2Fthird_party%2Fcnn%2Fcnn.xmlaf6df%0aalert(1)//70d7901fece&container=ig&view=home&lang=en&country=US&sanitize=0&v=e953aed2517e5bee&parent=http://www.google.com&libs=core:core.io:core.iglegacy:auth-refresh&synd=ig&view=home HTTP/1.1
Host: www.ig.gmodules.com
Proxy-Connection: keep-alive
Referer: http://www.google.com/ig
Accept: application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/534.13 (KHTML, like Gecko) Chrome/9.0.597.107 Safari/534.13
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3

Response

HTTP/1.1 400 Bad Request
P3P: CP="CAO PSA OUR"
Content-Type: text/html; charset=UTF-8
Date: Tue, 01 Mar 2011 21:54:05 GMT
Expires: Tue, 01 Mar 2011 21:54:05 GMT
Cache-Control: private, max-age=0
X-Content-Type-Options: nosniff
X-XSS-Protection: 1; mode=block
Server: GSE
Content-Length: 128

Unable to retrieve spec for http://www.gstatic.com/ig/modules/third_party/cnn/cnn.xmlaf6df
alert(1)//70d7901fece. HTTP error 400
2. Cross-domain Referer leakage  previous  next

Summary

Severity:   Information
Confidence:   Certain
Host:   http://www.ig.gmodules.com
Path:   /gadgets/ifr

Issue detail

The page was loaded from a URL containing a query string:The response contains the following links to other domains:

Issue background

When a web browser makes a request for a resource, it typically adds an HTTP header, called the "Referer" header, indicating the URL of the resource from which the request originated. This occurs in numerous situations, for example when a web page loads an image or script, or when a user clicks on a link or submits a form.

If the resource being requested resides on a different domain, then the Referer header is still generally included in the cross-domain request. If the originating URL contains any sensitive information within its query string, such as a session token, then this information will be transmitted to the other domain. If the other domain is not fully trusted by the application, then this may lead to a security compromise.

You should review the contents of the information being transmitted to other domains, and also determine whether those domains are fully trusted by the originating application.

Today's browsers may withhold the Referer header in some situations (for example, when loading a non-HTTPS resource from a page that was loaded over HTTPS, or when a Refresh directive is issued), but this behaviour should not be relied upon to protect the originating URL from disclosure.

Note also that if users can author content within the application then an attacker may be able to inject links referring to a domain they control in order to capture data from URLs used within the application.

Issue remediation

The application should never transmit any sensitive information within the URL query string. In addition to being leaked in the Referer header, such information may be logged in various locations and may be visible on-screen to untrusted parties.

Request

GET /gadgets/ifr?exp_rpc_js=1&exp_track_js=1&url=http%3A%2F%2Fwww.gstatic.com%2Fig%2Fmodules%2Fthird_party%2Fcnn%2Fcnn.xml&container=ig&view=home&lang=en&country=US&sanitize=0&v=e953aed2517e5bee&parent=http://www.google.com&libs=core:core.io:core.iglegacy:auth-refresh&synd=ig&view=home HTTP/1.1
Host: www.ig.gmodules.com
Proxy-Connection: keep-alive
Referer: http://www.google.com/ig
Accept: application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/534.13 (KHTML, like Gecko) Chrome/9.0.597.107 Safari/534.13
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3

Response

HTTP/1.1 200 OK
P3P: CP="CAO PSA OUR"
Content-Type: text/html; charset=UTF-8
Expires: Tue, 01 Mar 2011 21:52:53 GMT
Pragma: no-cache
Cache-Control: no-cache
Date: Tue, 01 Mar 2011 21:52:53 GMT
X-Content-Type-Options: nosniff
X-XSS-Protection: 1; mode=block
Server: GSE
Content-Length: 25172

<html><head><style type="text/css">body,td,div,span,p{font-family:arial,sans-serif;}a {color:#0000cc;}a:visited {color:#551a8b;}a:active {color:#ff0000;}body{margin: 0px;padding: 0px;background-color:
...[SNIP]...
<td align="right" valign="top">
<img border="0" onclick="closeBreakingNews();" src="http://www.gstatic.com/ig/modules/third_party/cnn/close.cache.png">
</td>
...[SNIP]...
<div class="loading">
<img src="http://www.google.com/ig/images/spinner.gif">
&nbsp;&nbsp;Loading...
</div>
...[SNIP]...
<span style="padding:3px;">
<img src="http://www.google.com/c.gif" border="0" class="play-img" id="play-img-{index}" onmouseover="playOver(this)" onmouseout="playOver(this);"/>
</span>
...[SNIP]...
3. Robots.txt file  previous  next

Summary

Severity:   Information
Confidence:   Certain
Host:   http://www.ig.gmodules.com
Path:   /gadgets/js/rpc.js

Issue detail

The web server contains a robots.txt file.

Issue background

The file robots.txt is used to give instructions to web robots, such as search engine crawlers, about locations within the web site which robots are allowed, or not allowed, to crawl and index.

The presence of the robots.txt does not in itself present any kind of security vulnerability. However, it is often used to identify restricted or private areas of a site's contents. The information in the file may therefore help an attacker to map out the site's contents, especially if some of the locations identified are not linked from elsewhere in the site. If the application relies on robots.txt to protect access to these areas, and does not enforce proper access control over them, then this presents a serious vulnerability.

Issue remediation

The robots.txt file is not itself a security threat, and its correct use can represent good practice for non-security reasons. You should not assume that all web robots will honour the file's instructions. Rather, assume that attackers will pay close attention to any locations identified in the file. Do not rely on robots.txt to provide any kind of protection over unauthorised access.

Request

GET /robots.txt HTTP/1.0
Host: www.ig.gmodules.com

Response

HTTP/1.0 200 OK
Content-Type: text/plain
Last-Modified: Mon, 28 Feb 2011 19:38:06 GMT
Date: Tue, 01 Mar 2011 21:52:52 GMT
Expires: Tue, 01 Mar 2011 21:52:52 GMT
Cache-Control: private, max-age=0
Vary: Accept-Encoding
X-Content-Type-Options: nosniff
Server: sffe
X-XSS-Protection: 1; mode=block

User-agent: *
Disallow: /search
Disallow: /groups
Disallow: /images
Disallow: /catalogs
Disallow: /catalogues
Disallow: /news
Allow: /news/directory
Disallow: /nwshp
Disallow: /setnewsprefs?
Disallow:
...[SNIP]...
4. Content type incorrectly stated  previous

Summary

Severity:   Information
Confidence:   Firm
Host:   http://www.ig.gmodules.com
Path:   /gadgets/makeRequest

Issue detail

The response contains the following Content-type statement:The response states that it contains JSON. However, it actually appears to contain unrecognised content.

Issue background

If a web response specifies an incorrect content type, then browsers may process the response in unexpected ways. If the specified content type is a renderable text-based format, then the browser will usually attempt to parse and render the response in that format. If the specified type is an image format, then the browser will usually detect the anomaly and will analyse the actual content and attempt to determine its MIME type. Either case can lead to unexpected results, and if the content contains any user-controllable data may lead to cross-site scripting or other client-side vulnerabilities.

In most cases, the presence of an incorrect content type statement does not constitute a security flaw, particularly if the response contains static content. You should review the contents of the response and the context in which it appears to determine whether any vulnerability exists.

Issue remediation

For every response containing a message body, the application should include a single Content-type header which correctly and unambiguously states the MIME type of the content in the response body.

Request

GET /gadgets/makeRequest?refresh=3600&url=http%3A%2F%2Fwww.cnn.com%2Fpartners%2Fgoogle%2Fcnn_igoogle_gadget_breakingnews.rss%3Fnocache%3D4330054&httpMethod=GET&headers=&postData=&authz=&st=&contentType=DOM&numEntries=3&getSummaries=false&signOwner=true&signViewer=true&gadget=http%3A%2F%2Fwww.gstatic.com%2Fig%2Fmodules%2Fthird_party%2Fcnn%2Fcnn.xml&container=ig&bypassSpecCache=&getFullHeaders=false HTTP/1.1
Host: www.ig.gmodules.com
Proxy-Connection: keep-alive
Referer: http://www.ig.gmodules.com/gadgets/ifr?exp_rpc_js=1&exp_track_js=1&url=http%3A%2F%2Fwww.gstatic.com%2Fig%2Fmodules%2Fthird_party%2Fcnn%2Fcnn.xml&container=ig&view=home&lang=en&country=US&sanitize=0&v=e953aed2517e5bee&parent=http://www.google.com&libs=core:core.io:core.iglegacy:auth-refresh&synd=ig&view=home
Accept: */*
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/534.13 (KHTML, like Gecko) Chrome/9.0.597.107 Safari/534.13
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3

Response

HTTP/1.1 200 OK
Expires: Tue, 01 Mar 2011 22:28:37 GMT
Content-Disposition: attachment;filename=p.txt
Content-Type: application/json; charset=UTF-8
Date: Tue, 01 Mar 2011 21:28:37 GMT
X-Content-Type-Options: nosniff
X-Frame-Options: SAMEORIGIN
X-XSS-Protection: 1; mode=block
Server: GSE
Cache-Control: public,max-age=3600
Age: 1457
Content-Length: 932

throw 1; < don't be evil' >{"http://www.cnn.com/partners/google/cnn_igoogle_gadget_breakingnews.rss?nocache=4330054":{"headers":{"set-cookie":["CG=US:CA:Mountain+View; path=/"]},"body":"\u003c?xml ver
...[SNIP]...
Report generated by XSS.CX at Sun Mar 06 10:18:44 CST 2011.