XSS, Reflected Cross Site Scripting, CWE-79, CAPEC-86, DORK, GHDB, acunote.com

Report generated by XSS.CX at Fri Jun 24 06:15:21 CDT 2011.

Public Domain Vulnerability Information, Security Articles, Vulnerability Reports, GHDB, DORK Search

1. Cross-site scripting (reflected) next

Summary

Severity:	High
Confidence:	Certain
Host:	http://www.acunote.com
Path:	/promo/login

Issue detail

The value of the email request parameter is copied into the HTML document as plain text between tags. The payload 5ab08<script>alert(1)</script>7e7d8203339 was submitted in the email 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.

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

POST /promo/login HTTP/1.1
Host: www.acunote.com
Proxy-Connection: keep-alive
Referer: http://www.acunote.com/promo/login
Content-Length: 104
Cache-Control: max-age=0
Origin: http://www.acunote.com
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/534.24 (KHTML, like Gecko) Chrome/11.0.696.77 Safari/534.24
Content-Type: application/x-www-form-urlencoded
Accept: application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
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: __utmz=20907432.1308913546.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); __utma=20907432.875879814.1308913546.1308913546.1308913546.1; __utmc=20907432; __utmb=20907432.2.10.1308913546

authenticity_token=P6Um2vksfd6LN8%2Fb6niNv6zxRe8JY0QPRC1Yc72glBo%3D&email=5ab08<script>alert(1)</script>7e7d8203339&commit=Remind+My+Company+Link

Response

HTTP/1.1 200 OK
Server: nginx/0.6.32
Date: Fri, 24 Jun 2011 11:10:48 GMT
Content-Type: text/html; charset=utf-8
Connection: keep-alive
Status: 200 OK
ETag: "3a397219ad62500418f29ca9c6f274f7"
X-Runtime: 16
Set-Cookie: _acunote_session_id=ccef95c18e2e09fb1a8407b55803b21b; path=/; HttpOnly
Cache-Control: private, max-age=0, must-revalidate
Content-Length: 4294

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-T
...[SNIP]...
<b>5ab08<script>alert(1)</script>7e7d8203339</b>
...[SNIP]...

2. Robots.txt file previous

Summary

Severity:	Information
Confidence:	Certain
Host:	http://www.acunote.com
Path:	/promo

Issue detail

The web server contains a robots.txt file.

Issue background

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: www.acunote.com

Response

HTTP/1.1 200 OK
Server: nginx/0.6.32
Date: Fri, 24 Jun 2011 11:05:44 GMT
Content-Type: text/plain
Content-Length: 294
Last-Modified: Mon, 26 Apr 2010 12:47:40 GMT
Connection: close
Accept-Ranges: bytes

# See http://www.robotstxt.org/wc/norobots.html for documentation on how to use the robots.txt file

User-agent: *
Disallow: /competitors/ # Landings should not be indexed
Disallow: /e/ # Ex
...[SNIP]...

Report generated by XSS.CX at Fri Jun 24 06:15:21 CDT 2011.