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 organization. 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 organization 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 organization 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 sanitized.
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 new_display request parameter is copied into the value of an HTML tag attribute which is encapsulated in double quotation marks. The payload 4e921"><script>alert(1)</script>6b5b5ccb9f8dcbc50 was submitted in the new_display parameter. This input was echoed as 4e921\"><script>alert(1)</script>6b5b5ccb9f8dcbc50 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 original request used the POST method, however it was possible to convert the request to use the GET method, to enable easier demonstration and delivery of the attack.
The value of the new_email request parameter is copied into the value of an HTML tag attribute which is encapsulated in double quotation marks. The payload 9fd3d"><script>alert(1)</script>6b35b87c6883e12a9 was submitted in the new_email parameter. This input was echoed as 9fd3d\"><script>alert(1)</script>6b35b87c6883e12a9 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 original request used the POST method, however it was possible to convert the request to use the GET method, to enable easier demonstration and delivery of the attack.
The value of the new_icq request parameter is copied into the value of an HTML tag attribute which is encapsulated in double quotation marks. The payload 9cf47"><script>alert(1)</script>1659fd3f313619164 was submitted in the new_icq parameter. This input was echoed as 9cf47\"><script>alert(1)</script>1659fd3f313619164 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 original request used the POST method, however it was possible to convert the request to use the GET method, to enable easier demonstration and delivery of the attack.
The value of the new_user request parameter is copied into the value of an HTML tag attribute which is encapsulated in double quotation marks. The payload 58910"><script>alert(1)</script>e1db7cdf8dbc292eb was submitted in the new_user parameter. This input was echoed as 58910\"><script>alert(1)</script>e1db7cdf8dbc292eb 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 original request used the POST method, however it was possible to convert the request to use the GET method, to enable easier demonstration and delivery of the attack.
The value of the user_refer_text request parameter is copied into the value of an HTML tag attribute which is encapsulated in double quotation marks. The payload 8bb43"><script>alert(1)</script>702f4c1a62041145a was submitted in the user_refer_text parameter. This input was echoed as 8bb43\\\"><script>alert(1)</script>702f4c1a62041145a 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 original request used the POST method, however it was possible to convert the request to use the GET method, to enable easier demonstration and delivery of the attack.
The page contains a form with the following action URL, which is submitted over clear-text HTTP:
http://clients.websitesecure.org/
The form contains the following password fields:
new_password
new_passwordR
Issue background
Passwords submitted over an unencrypted connection are vulnerable to capture by an attacker who is suitably positioned on the network. This includes any malicious party located on the user's own network, within their ISP, within the ISP used by the application, and within the application's hosting infrastructure. Even if switched networks are employed at some of these locations, techniques exist to circumvent this defense and monitor the traffic passing through switches.
Issue remediation
The application should use transport-level encryption (SSL or TLS) to protect all sensitive communications passing between the client and the server. Communications that should be protected include the login mechanism and related functionality, and any functions where sensitive data can be accessed or privileged actions can be performed. These areas of the application should employ their own session handling mechanism, and the session tokens used should never be transmitted over unencrypted communications. If HTTP cookies are used for transmitting session tokens, then the secure flag should be set to prevent transmission over clear-text HTTP.
3. Password field submitted using GET methodpreviousnext
Summary
Severity:
Low
Confidence:
Certain
Host:
http://clients.websitesecure.org
Path:
/
Issue detail
The page contains a form with the following action URL, which is submitted using the GET method:
https://clients.websitesecure.org/login.php
The form contains the following password field:
password
Issue background
The application uses the GET method to submit passwords, which are transmitted within the query string of the requested URL. 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 passwords into the URL increases the risk that they will be captured by an attacker.
Issue remediation
All forms submitting passwords should use the POST method. To achieve this, you should specify the method attribute of the FORM tag as method="POST". It may also be necessary to modify the corresponding server-side form handler to ensure that submitted passwords are properly retrieved from the message body, rather than the URL.
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.
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).
If a web response states that it contains HTML content but does not specify a character set, then the browser may analyze 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 recognized character set, for example charset=ISO-8859-1.