Difference between revisions of "J2EE Bad Practices: JSP Expressions"

From OWASP
Jump to: navigation, search
(Reverting to last version not containing links to www.textcooucalideln.com)
 
(5 intermediate revisions by 2 users not shown)
Line 1: Line 1:
{{Template:Vulnerability}}
+
{{template:CandidateForDeletion}}
{{Template:Stub}}
+
 
 +
#REDIRECT [[Failure to follow guideline/specification]]
  
[[Category:FIXME|This is the text from the old template. This needs to be rewritten using the new template.]]
 
  
 
Last revision (mm/dd/yy): '''{{REVISIONMONTH}}/{{REVISIONDAY}}/{{REVISIONYEAR}}'''
 
Last revision (mm/dd/yy): '''{{REVISIONMONTH}}/{{REVISIONDAY}}/{{REVISIONYEAR}}'''
  
[[ASDR_TOC_Vulnerabilities|Vulnerabilities Table of Contents]]
 
 
[[ASDR Table of Contents]]
 
__TOC__
 
 
[[Category:FIXME|Stub article, needs review]]
 
 
==Description==
 
==Description==
  
Line 81: Line 75:
 
* [[Vulnerability 1]]
 
* [[Vulnerability 1]]
 
* [[Vulnerabiltiy 2]]
 
* [[Vulnerabiltiy 2]]
 
Note: the contents of "Related Problems" sections should be placed here
 
  
  
Line 103: Line 95:
 
* http://www.link1.com
 
* http://www.link1.com
 
* [http://www.link2.com Title for the link2]
 
* [http://www.link2.com Title for the link2]
 
[[Category:FIXME|add links
 
 
In addition, one should classify vulnerability based on the following subcategories: Ex:<nowiki>[[Category:Error Handling Vulnerability]]</nowiki>
 
 
Availability Vulnerability
 
 
Authorization Vulnerability
 
 
Authentication Vulnerability
 
 
Concurrency Vulnerability
 
 
Configuration Vulnerability
 
 
Cryptographic Vulnerability
 
 
Encoding Vulnerability
 
 
Error Handling Vulnerability
 
 
Input Validation Vulnerability
 
 
Logging and Auditing Vulnerability
 
 
Session Management Vulnerability]]
 
 
__NOTOC__
 
 
 
[[Category:OWASP ASDR Project]]
 
[[Category:Vulnerability]]
 
[[Category:Implementation]]
 
[[Category:Java]]
 
[[Category:Use of Dangerous API]]
 

Latest revision as of 13:30, 27 May 2009


This page was marked to be reviewed for deletion.


#REDIRECT Failure to follow guideline/specification


Last revision (mm/dd/yy): 05/27/2009

Contents

Description

JSP 2.0 introduced a new capability allowing one to use JSP Expressions directly within the template text (i.e. outside of tag libraries or tag files) of a web page. However, improper use of the expressions will leave an application open to XSS Attacks.

Consequences

  • Failing to use JSP Expressions properly will leave an application open to XSS Attacks.

Exposure period This vulnerability has existed since servlet containers and application servers began implementing the [JSP 2.0 standard]

Platform

  • Languages: Java/JSP

Severity High

Likelihood of exploit If a developer uses JSP Expressions to write unsanitized, user-entered data to a page, the likelihood of exploit is very high.


Risk Factors

TBD


Examples

JSP 2.0 expressions allow developers to expose data and objects stored in application, session, request, or page scope using an Ant-style syntax. It allows you to replace this

<table>
    <c:forEach var="book" items="${books}">
        <tr>
            <td><c:out value="${book.title}"/></td>
            <td><c:out value="${book.author}"/></td>
            <td><c:out value="${book.isbn}"/></td>
        </tr> 
    </c:forEach>
</table>

with this

<table>
    <c:forEach var="book" items="${books}">
        <tr>
            <td>${book.title}</td>
            <td>${book.author}</td>
            <td>${book.isbn}</td>
        </tr>
    </c:forEach>
</table>

As you can see, the syntax in the second example is more succinct. However, it may also expose a Cross Site Scripting XSS vulnerability. The problem that few tutorials (including Sun's Java EE 5 Tutorial) mention is that the expression syntax does not escape HTML characters. Therefore, any web application using JSP Expressions to output unsanitized, user-entered data will be vulnerable to Cross Site Scripting (XSS) attacks.


Related Attacks


Related Vulnerabilities


Related Controls

The safest cure for this XSS vulnerability leads one right back to the first example. As section 2.2.2 of the JSP 2.0 Specification reads, “In cases where escaping is desired (for example, to help prevent cross-site scripting attacks), the JSTL core tag c:out can be used.”

To be sure your code is not vulnerable to the potential XSS vulnerability described herein, use JSP Expressions only as tag library attribute values and stick to using JSTL‘s c:out tag for writing text to a page. Deciding which instances of template text expression usage are safe and which are not is error prone and the consequences of a mistake are grave.

Related Technical Impacts


References

Note: A reference to related CWE or CAPEC article should be added when exists. Eg: