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.
The value of the session_id request parameter is copied into the value of an HTML tag attribute which is encapsulated in double quotation marks. The payload 925f5"><script>alert(1)</script>47218cdf34a was submitted in the session_id 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 /Merchant2/merchant.mv?screen=LOGN&order=1&session_id=925f5"><script>alert(1)</script>47218cdf34a HTTP/1.1 Host: www.mivacentral.com Accept: */* Accept-Language: en User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0) Connection: close Cookie: __utmz=257814807.1293935382.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); __utma=257814807.282849387.1293935382.1293935382.1293935382.1; __utmc=257814807; htscallerid=4D1FE34D0006713E00004DFF00000000; __utmb=257814807.1.10.1293935382;
Response
HTTP/1.0 200 OK Date: Sun, 02 Jan 2011 04:08:53 GMT Server: Apache Set-Cookie: htscallerid=4D1FE34D0006713E00004DFF00000000; expires=Mon, 02-Jan-2012 04:08:53 GMT; path=/ P3P: CP="NOI DEVa TAIa OUR BUS UNI STA", policyref="http://www.mivacentral.com/w3c/p3p.xml" Connection: close Content-Type: text/html
The value of the htscallerid cookie is copied into the value of an HTML tag attribute which is encapsulated in double quotation marks. The payload fb118"><script>alert(1)</script>7f93eeb7776 was submitted in the htscallerid 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 /Merchant2/merchant.mv HTTP/1.1 Host: www.mivacentral.com Accept: */* Accept-Language: en User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0) Connection: close Cookie: __utmz=257814807.1293935382.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); __utma=257814807.282849387.1293935382.1293935382.1293935382.1; __utmc=257814807; htscallerid=4D1FE34D0006713E00004DFF00000000fb118"><script>alert(1)</script>7f93eeb7776; __utmb=257814807.1.10.1293935382;
Response
HTTP/1.0 200 OK Date: Sun, 02 Jan 2011 04:09:08 GMT Server: Apache Set-Cookie: htscallerid=4D1FE34D0006713E00004DFF00000000fb118"><script>alert(1)</script>7f93eeb7776; expires=Mon, 02-Jan-2012 04:09:08 GMT; path=/ P3P: CP="NOI DEVa TAIa OUR BUS UNI STA", policyref="http://www.mivacentral.com/w3c/p3p.xml" Connection: close Content-Type: text/html
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 /Merchant2/merchant.mv?screen=LOGN&order=1&session_id= HTTP/1.1 Host: www.mivacentral.com Accept: */* Accept-Language: en User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0) Connection: close Cookie: __utmz=257814807.1293935382.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); __utma=257814807.282849387.1293935382.1293935382.1293935382.1; __utmc=257814807; htscallerid=4D1FE34D0006713E00004DFF00000000; __utmb=257814807.1.10.1293935382;
Response
HTTP/1.0 200 OK Date: Sun, 02 Jan 2011 04:02:05 GMT Server: Apache Set-Cookie: htscallerid=4D1FE34D0006713E00004DFF00000000; expires=Mon, 02-Jan-2012 04:02:05 GMT; path=/ P3P: CP="NOI DEVa TAIa OUR BUS UNI STA", policyref="http://www.mivacentral.com/w3c/p3p.xml" Connection: close Content-Type: text/html
<HTML>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <html> <HEAD> <TITLE> Miva ...[SNIP]... <img src="/imagesgen4/checkout_icon.gif" alt="Checkout" border="0" class="toplinkicon"> <a href="https://www.mivacentral.com/Merchant2/merchant.mv?screen=LOGN&order=1&session_id=4D1FE34D0006713E00004DFF00000000"> <div class="toplinktext" style="color: #730000"> ...[SNIP]... <FONT FACE="Arial, Helvetica" SIZE="-1"> <A HREF="https://www.mivacentral.com/Merchant2/merchant.mv?Session_ID=4D1FE34D0006713E00004DFF00000000&Screen=ACNT&Order=1&Store_Code=m">Create New Account</A> ...[SNIP]... <FONT FACE="Arial, Helvetica" SIZE="-1"> <A HREF="https://www.mivacentral.com/Merchant2/merchant.mv?Session_ID=4D1FE34D0006713E00004DFF00000000&Screen=OINF&Store_Code=m">Place Order Without Account</A> ...[SNIP]...
3. Password field with autocomplete enabledpreviousnext There are 2 instances of this issue:
Most browsers have a facility to remember user credentials that are entered into HTML forms. This function can be configured by the user and also by applications which employ user credentials. If the function is enabled, then credentials entered by the user are stored on their local computer and retrieved by the browser on future visits to the same application.
The stored credentials can be captured by an attacker who gains access to the computer, either locally or through some remote compromise. Further, methods have existed whereby a malicious web site can retrieve the stored credentials for other applications, by exploiting browser vulnerabilities or through application-level cross-domain attacks.
Issue remediation
To prevent browsers from storing credentials entered into HTML forms, you should include the attribute autocomplete="off" within the FORM tag (to protect all form fields) or within the relevant INPUT tags (to protect specific individual fields).
The form contains the following password field with autocomplete enabled:
Customer_Password
Request
GET /Merchant2/merchant.mv?screen=LOGN&order=1&session_id= HTTP/1.1 Host: www.mivacentral.com Accept: */* Accept-Language: en User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0) Connection: close Cookie: __utmz=257814807.1293935382.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); __utma=257814807.282849387.1293935382.1293935382.1293935382.1; __utmc=257814807; htscallerid=4D1FE34D0006713E00004DFF00000000; __utmb=257814807.1.10.1293935382;
Response
HTTP/1.0 200 OK Date: Sun, 02 Jan 2011 04:02:05 GMT Server: Apache Set-Cookie: htscallerid=4D1FE34D0006713E00004DFF00000000; expires=Mon, 02-Jan-2012 04:02:05 GMT; path=/ P3P: CP="NOI DEVa TAIa OUR BUS UNI STA", policyref="http://www.mivacentral.com/w3c/p3p.xml" Connection: close Content-Type: text/html
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 secure flag is set on a cookie, then browsers will not submit the cookie in any requests that use an unencrypted HTTP connection, thereby preventing the cookie from being trivially intercepted by an attacker monitoring network traffic. If the secure flag is not set, then the cookie will be transmitted in clear-text if the user visits any HTTP URLs within the cookie's scope. An attacker may be able to induce this event by feeding a user suitable links, either directly or via another web site. Even if the domain which issued the cookie does not host any content that is accessed over HTTP, an attacker may be able to use links of the form http://example.com:443/ to perform the same attack.
Issue remediation
The secure flag should be set on all cookies that are used for transmitting sensitive data when accessing content over HTTPS. If cookies are used to transmit session tokens, then areas of the application that are accessed over HTTPS should employ their own session handling mechanism, and the session tokens used should never be transmitted over unencrypted communications.
Request
GET /Merchant2/merchant.mv?screen=LOGN&order=1&session_id= HTTP/1.1 Host: www.mivacentral.com Accept: */* Accept-Language: en User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0) Connection: close Cookie: __utmz=257814807.1293935382.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); __utma=257814807.282849387.1293935382.1293935382.1293935382.1; __utmc=257814807; htscallerid=4D1FE34D0006713E00004DFF00000000; __utmb=257814807.1.10.1293935382;
Response
HTTP/1.0 200 OK Date: Sun, 02 Jan 2011 04:02:05 GMT Server: Apache Set-Cookie: htscallerid=4D1FE34D0006713E00004DFF00000000; expires=Mon, 02-Jan-2012 04:02:05 GMT; path=/ P3P: CP="NOI DEVa TAIa OUR BUS UNI STA", policyref="http://www.mivacentral.com/w3c/p3p.xml" Connection: close Content-Type: text/html
<HTML>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <html> <HEAD> <TITLE> Miva ...[SNIP]...
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 /Merchant2/merchant.mv?screen=LOGN&order=1&session_id= HTTP/1.1 Host: www.mivacentral.com Accept: */* Accept-Language: en User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0) Connection: close Cookie: __utmz=257814807.1293935382.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); __utma=257814807.282849387.1293935382.1293935382.1293935382.1; __utmc=257814807; htscallerid=4D1FE34D0006713E00004DFF00000000; __utmb=257814807.1.10.1293935382;
Response
HTTP/1.0 200 OK Date: Sun, 02 Jan 2011 04:02:05 GMT Server: Apache Set-Cookie: htscallerid=4D1FE34D0006713E00004DFF00000000; expires=Mon, 02-Jan-2012 04:02:05 GMT; path=/ P3P: CP="NOI DEVa TAIa OUR BUS UNI STA", policyref="http://www.mivacentral.com/w3c/p3p.xml" Connection: close Content-Type: text/html
When an application includes a script from an external domain, this script is executed by the browser within the security context of the invoking application. The script can therefore do anything that the application's own scripts can do, such as accessing application data and performing actions within the context of the current user.
If you include a script from an external domain, then you are trusting that domain with the data and functionality of your application, and you are trusting the domain's own security to prevent an attacker from modifying the script to perform malicious actions within your application.
Issue remediation
Scripts should not be included from untrusted domains. If you have a requirement which a third-party script appears to fulfil, then you should ideally copy the contents of that script onto your own domain and include it from there. If that is not possible (e.g. for licensing reasons) then you should consider reimplementing the script's functionality within your own code.
Request
GET /Merchant2/merchant.mv?screen=LOGN&order=1&session_id= HTTP/1.1 Host: www.mivacentral.com Accept: */* Accept-Language: en User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0) Connection: close Cookie: __utmz=257814807.1293935382.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); __utma=257814807.282849387.1293935382.1293935382.1293935382.1; __utmc=257814807; htscallerid=4D1FE34D0006713E00004DFF00000000; __utmb=257814807.1.10.1293935382;
Response
HTTP/1.0 200 OK Date: Sun, 02 Jan 2011 04:02:05 GMT Server: Apache Set-Cookie: htscallerid=4D1FE34D0006713E00004DFF00000000; expires=Mon, 02-Jan-2012 04:02:05 GMT; path=/ P3P: CP="NOI DEVa TAIa OUR BUS UNI STA", policyref="http://www.mivacentral.com/w3c/p3p.xml" Connection: close Content-Type: text/html
<HTML>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <html> <HEAD> <TITLE> Miva ...[SNIP]... <link rel="shortcut icon" href="http://www.mivacentral.com/favicon.ico" type="image/x-icon"> <script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.2.6/jquery.min.js"></script> ...[SNIP]...
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
GET /Merchant2/merchant.mv?screen=LOGN&order=1&session_id= HTTP/1.1 Host: www.mivacentral.com Accept: */* Accept-Language: en User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0) Connection: close Cookie: __utmz=257814807.1293935382.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); __utma=257814807.282849387.1293935382.1293935382.1293935382.1; __utmc=257814807; htscallerid=4D1FE34D0006713E00004DFF00000000; __utmb=257814807.1.10.1293935382;
Response
HTTP/1.0 200 OK Date: Sun, 02 Jan 2011 04:02:05 GMT Server: Apache Set-Cookie: htscallerid=4D1FE34D0006713E00004DFF00000000; expires=Mon, 02-Jan-2012 04:02:05 GMT; path=/ P3P: CP="NOI DEVa TAIa OUR BUS UNI STA", policyref="http://www.mivacentral.com/w3c/p3p.xml" Connection: close Content-Type: text/html
<HTML>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <html> <HEAD> <TITLE> Miva ...[SNIP]...
Unless directed otherwise, browsers may store a local cached copy of content received from web servers. Some browsers, including Internet Explorer, cache content accessed via HTTPS. If sensitive information in application responses is stored in the local cache, then this may be retrieved by other users who have access to the same computer at a future time.
Issue remediation
The application should return caching directives instructing browsers not to store local copies of any sensitive data. Often, this can be achieved by configuring the web server to prevent caching for relevant paths within the web root. Alternatively, most web development platforms allow you to control the server's caching directives from within individual scripts. Ideally, the web server should return the following HTTP headers in all responses containing sensitive content:
Cache-control: no-store
Pragma: no-cache
Request
GET /Merchant2/merchant.mv?screen=LOGN&order=1&session_id= HTTP/1.1 Host: www.mivacentral.com Accept: */* Accept-Language: en User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0) Connection: close Cookie: __utmz=257814807.1293935382.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); __utma=257814807.282849387.1293935382.1293935382.1293935382.1; __utmc=257814807; htscallerid=4D1FE34D0006713E00004DFF00000000; __utmb=257814807.1.10.1293935382;
Response
HTTP/1.0 200 OK Date: Sun, 02 Jan 2011 04:02:05 GMT Server: Apache Set-Cookie: htscallerid=4D1FE34D0006713E00004DFF00000000; expires=Mon, 02-Jan-2012 04:02:05 GMT; path=/ P3P: CP="NOI DEVa TAIa OUR BUS UNI STA", policyref="http://www.mivacentral.com/w3c/p3p.xml" Connection: close Content-Type: text/html
<HTML>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <html> <HEAD> <TITLE> Miva ...[SNIP]...
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
GET /Merchant2/merchant.mv?screen=LOGN&order=1&session_id= HTTP/1.1 Host: www.mivacentral.com Accept: */* Accept-Language: en User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0) Connection: close Cookie: __utmz=257814807.1293935382.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); __utma=257814807.282849387.1293935382.1293935382.1293935382.1; __utmc=257814807; htscallerid=4D1FE34D0006713E00004DFF00000000; __utmb=257814807.1.10.1293935382;
Response
HTTP/1.0 200 OK Date: Sun, 02 Jan 2011 04:02:05 GMT Server: Apache Set-Cookie: htscallerid=4D1FE34D0006713E00004DFF00000000; expires=Mon, 02-Jan-2012 04:02:05 GMT; path=/ P3P: CP="NOI DEVa TAIa OUR BUS UNI STA", policyref="http://www.mivacentral.com/w3c/p3p.xml" Connection: close Content-Type: text/html
<HTML>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <html> <HEAD> <TITLE> Miva ...[SNIP]...
The server presented a valid, trusted SSL certificate. This issue is purely informational.
The server presented the following certificates:
Server certificate
Issued to:
www.mivacentral.com
Issued by:
VeriSign Class 3 Extended Validation SSL CA
Valid from:
Tue Sep 29 19:00:00 CDT 2009
Valid to:
Fri Aug 12 18:59:59 CDT 2011
Certificate chain #1
Issued to:
VeriSign Class 3 Extended Validation SSL CA
Issued by:
VeriSign Class 3 Public Primary Certification Authority - G5
Valid from:
Tue Nov 07 18:00:00 CST 2006
Valid to:
Mon Nov 07 17:59:59 CST 2016
Certificate chain #2
Issued to:
VeriSign Class 3 Public Primary Certification Authority - G5
Issued by:
Class 3 Public Primary Certification Authority
Valid from:
Tue Nov 07 18:00:00 CST 2006
Valid to:
Sun Nov 07 17:59:59 CST 2021
Certificate chain #3
Issued to:
Class 3 Public Primary Certification Authority
Issued by:
Class 3 Public Primary Certification Authority
Valid from:
Sun Jan 28 18:00:00 CST 1996
Valid to:
Wed Aug 02 18:59:59 CDT 2028
Issue background
SSL helps to protect the confidentiality and integrity of information in transit between the browser and server, and to provide authentication of the server's identity. To serve this purpose, the server must present an SSL certificate which is valid for the server's hostname, is issued by a trusted authority and is valid for the current date. If any one of these requirements is not met, SSL connections to the server will not provide the full protection for which SSL is designed.
It should be noted that various attacks exist against SSL in general, and in the context of HTTPS web connections. It may be possible for a determined and suitably-positioned attacker to compromise SSL connections without user detection even when a valid SSL certificate is used.Report generated by XSS.CX at Sun Jan 02 06:55:52 CST 2011.