implement xss (mitigation) assignment 6

This commit is contained in:
Marvin Schöning
2019-03-03 16:42:29 +01:00
committed by Nanne Baars
parent a8106f6671
commit b8e68d13b8
5 changed files with 149 additions and 1 deletions

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@ -38,4 +38,24 @@
</div>
</div>
<div class="lesson-page-wrapper">
<div class="adoc-content" th:replace="doc:CrossSiteScripting_content8c.adoc"></div>
<div class="attack-container" style="height: 100%; border: none !important;min-height: 450px;">
<form id="codesubmit2" style="height: 100%; min-height: 350px;" class="attack-form" accept-charset="UNKNOWN" method="POST" name="form" action="/WebGoat/CrossSiteScripting/attack4" enctype="application/json;charset=UTF-8">
<div>
<div id="editor2" style="position: absolute; top: 0; right: 0; bottom: 0; left: 0; height: 350px;" name="editor2"></div>
<script th:src="@{/js/libs/ace/src-noconflict/ace.js}" type="text/javascript" charset="utf-8"></script>
<script th:src="@{/lesson_js/assignment4.js}" type="text/javascript" charset="utf-8"></script>
</div>
<input type="hidden" name="editor2"/>
<div class="input-group" style="position: absolute; top: 365px;">
<button class="btn btn-primary" type="submit">Submit</button>
</div>
</form>
<br />
<div class="attack-feedback" style="margin-top: 50px;"></div>
<div class="attack-output"></div>
</div>
</div>
</html>

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@ -36,4 +36,7 @@ xss-mitigation-3-hint3=Take a look at OWASP Java Encoder Project.
xss-mitigation-3-hint4=Do not forget to reference the tag libs and choose "e" as prefix.
xss-mitigation-3-success=You have completed this lesson. Congratulations!
xss-mitigation-3-failure=This in not the correct answer. Try again!
xss-mitigation-3-no-code=You did not change anything.
xss-mitigation-3-no-code=You did not change anything.
xss-mitigation-4-hint1=Try to have a look at the AntiSamy documentation.
xss-mitigation-4-success=You have completed this lesson. Congratulations!
xss-mitigation-4-failed=This is not the correct answer. Try again!

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@ -0,0 +1,30 @@
$(document).ready( () => {
var editor2 = ace.edit("editor2");
editor2.setTheme("ace/theme/monokai");
editor2.session.setMode("ace/mode/java");
editor2.getSession().on("change", () => {
setTimeout( () => {
$("#codesubmit2 input[name='editor2']").val(ace_collect2());
}, 20);
});
editor2.setValue(
"import org.owasp.validator.html.*;\n" +
"import MyCommentDAO;\n" +
"\n" +
"public class AntiSamyController {\n" +
" public void saveNewComment(int threadID, int userID, String newComment){\n" +
" MyCommentDAO.addComment(threadID, userID, newComment);\n" +
" }\n" +
"}"
);
});
function ace_collect2() {
var editor = ace.edit("editor2");
var code = editor.getValue();
return code;
}

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@ -0,0 +1,49 @@
== Stored XSS
One way to prevent stored XSS is the usage of https://www.owasp.org/index.php/Category:OWASP_AntiSamy_Project[OWASP AntiSamy]. AntiSamy is able to produce a "clean" string based on a modifiable policy file.
See the java class below which saves a comment into a database.
[source,java]
-------------------------------------------------------
public class MyCommentDAO {
public static void addComment(int threadID, int userID, String newComment) {
String sql = "INSERT INTO COMMENTS(THREADID, USERID, COMMENT) VALUES(?,?,?);";
try {
PreparedStatement stmt = connection.prepareStatement(sql);
stmt.setInt(1, threadID);
stmt.setInt(2, userID);
stmt.setString(3, newComment);
stmt.executeUpdate();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
-------------------------------------------------------
And here is a java class that is using the addComment function
[source,java]
-------------------------------------------------------
import org.owasp.validator.html.*;
import MyCommentDAO;
public class AntiSamyController {
...
public void saveNewComment(int threadID, int userID, String newComment){
MyCommentDAO.addComment(threadID, userID, newComment);
}
...
}
-------------------------------------------------------
As you can see the Java file stores unfiltered user input into the database.
Youll have the whole malicious code stored in your database now.
== Its your turn!
Try to prevent this kind of XSS by creating a clean string inside of the saveNewComment() function. Use the "antisamy-slashdot.xml" as policy file for this example: