# Security

Rules that flag potential security flaws.
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## IframeMissingSrcAttribute

Since: PMD 3.6

Priority: Medium High (2)

IFrames which are missing a src element can cause security information popups in IE if you are accessing the page through SSL. See http://support.microsoft.com/default.aspx?scid=kb;EN-US;Q261188

This rule is defined by the following XPath expression:

    //Element[upper-case(@Name)="IFRAME"][count(Attribute[upper-case(@Name)="SRC" ]) = 0]

Example(s):

    <HTML><title>bad example><BODY>
    <iframe></iframe>
    </BODY> </HTML>

    <HTML><title>good example><BODY>
    <iframe src="foo"></iframe>
    </BODY> </HTML>

Use this rule by referencing it:

    <rule ref="category/jsp/security.xml/IframeMissingSrcAttribute" />

## NoUnsanitizedJSPExpression

Since: PMD 5.1.4

Priority: Medium (3)

Avoid using expressions without escaping / sanitizing. This could lead to cross site scripting - as the expression would be interpreted by the browser directly (e.g. "<script>alert(‘hello’);</script>").

This rule is defined by the following Java class: net.sourceforge.pmd.lang.jsp.rule.security.NoUnsanitizedJSPExpressionRule

Example(s):

    <%@ page contentType="text/html; charset=UTF-8" %>
    <%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>
    ${expression}                    <!-- don't use this -->
    ${fn:escapeXml(expression)}      <!-- instead, escape it -->
    <c:out value="${expression}" />  <!-- or use c:out -->

Use this rule by referencing it:

    <rule ref="category/jsp/security.xml/NoUnsanitizedJSPExpression" />