Add extra documentation for using the correct algorithm but removing the signature.

webgoat-lessons/jwt/src/main/java/org/owasp/webgoat/jwt/JWTQuiz.java

@@ -12,7 +12,7 @@ import org.springframework.web.bind.annotation.RestController;
 @RestController
 public class JWTQuiz extends AssignmentEndpoint {
 
-    private final String[] solutions = {"Solution 1", "Solution 3"};
+    private final String[] solutions = {"Solution 1", "Solution 2"};
     private final boolean[] guesses = new boolean[solutions.length];
 
     @PostMapping("/JWT/quiz")

webgoat-lessons/jwt/src/main/resources/html/JWT.html

@@ -132,6 +132,18 @@
     </div>
 </div>
 
+<div class="lesson-page-wrapper">
+    <div class="lesson-page-solution">
+        <div class="adoc-content" th:replace="doc:JWT_libraries_assignment2.adoc"></div>
+    </div>
+</div>
+
+<div class="lesson-page-wrapper">
+    <div class="lesson-page-solution">
+        <div class="adoc-content" th:replace="doc:JWT_libraries_solution.adoc"></div>
+    </div>
+</div>
+
 <div class="lesson-page-wrapper">
     <div class="adoc-content" th:replace="doc:JWT_weak_keys"></div>
     <script th:src="@{/lesson_js/jwt-weak-keys.js}" language="JavaScript"></script>

webgoat-lessons/jwt/src/main/resources/lessonPlans/en/JWT_libraries_assignment.adoc

@@ -7,6 +7,22 @@ Now let's look at a code review and try to think on an attack with the `alg: non
 eyJhbGciOiJub25lIiwidHlwIjoiSldUIn0.eyJzdWIiOiIxMjM0NTY3ODkwIiwidXNlciI6IkpvaG4gRG9lIiwiYWRtaW4iOnRydWUsImlhdCI6MTUxNjIzOTAyMn0.
 ----
 
+which after decoding becomes:
+
+[source]
+----
+{
+  "alg" : "none",
+  "typ" : "JWT"
+},
+{
+  "admin" : true,
+  "iat" : 1516239022,
+  "sub" : "1234567890",
+  "user" : "John Doe"
+}
+----
+
 [source%linenums, java]
 ----
 try {
@@ -30,7 +46,7 @@ try {
    Jwt jwt = Jwts.parser().setSigningKey(JWT_PASSWORD).parse(accessToken);
    Claims claims = (Claims) jwt.getBody();
    String user = (String) claims.get("user");
-   boolean isAdmin = Boolean.valueOf((String) claims.get("admin"));
+   booelean isAdmin = Boolean.valueOf((String) claims.get("admin"));
    if (isAdmin) {
      removeAllUsers();
    } else {

webgoat-lessons/jwt/src/main/resources/lessonPlans/en/JWT_libraries_assignment2.adoc

@@ -0,0 +1,37 @@
+== Code review (2)
+
+Same as before but now we are only removing the signature part, leaving the algorithm as is.
+
+[source]
+----
+eyJhbGciOiJIUzI1NiJ9.ew0KICAiYWRtaW4iIDogdHJ1ZSwNCiAgImlhdCIgOiAxNTE2MjM5MDIyLA0KICAic3ViIiA6ICIxMjM0NTY3ODkwIiwNCiAgInVzZXIiIDogIkpvaG4gRG9lIg0KfQ.
+
+{
+  "alg" : "HS256"
+},
+{
+  "admin" : true,
+  "iat" : 1516239022,
+  "sub" : "1234567890",
+  "user" : "John Doe"
+}
+----
+
+Using the following `parse` method we are still able to skip the signature check.
+
+[source%linenums, java]
+----
+try {
+   Jwt jwt = Jwts.parser().setSigningKey(JWT_PASSWORD).parse(accessToken);
+   Claims claims = (Claims) jwt.getBody();
+   String user = (String) claims.get("user");
+   boolean isAdmin = Boolean.valueOf((String) claims.get("admin"));
+   if (isAdmin) {
+     removeAllUsers();
+   } else {
+     log.error("You are not an admin user");
+   }
+} catch (JwtException e) {
+  throw new InvalidTokenException(e);
+}
+----

webgoat-lessons/jwt/src/main/resources/lessonPlans/en/JWT_libraries_solution.adoc

@@ -0,0 +1,46 @@
+=== Solution
+
+In the past assignments we learned to **NOT** trust the libraries to do the correct thing for us. In both cases we saw that even specifying the JWT key and passing the correct algorithm. Even using the token:
+
+[source]
+----
+eyJhbGciOiJIUzI1NiJ9.ew0KICAiYWRtaW4iIDogdHJ1ZSwNCiAgImlhdCIgOiAxNTE2MjM5MDIyLA0KICAic3ViIiA6ICIxMjM0NTY3ODkwIiwNCiAgInVzZXIiIDogIkpvaG4gRG9lIg0KfQ.
+
+{
+  "alg" : "HS256"
+},
+{
+  "admin" : true,
+  "iat" : 1516239022,
+  "sub" : "1234567890",
+  "user" : "John Doe"
+}
+----
+
+And the following Java code:
+
+[source]
+----
+Jwt jwt = Jwts.parser().setSigningKey(JWT_PASSWORD).parse(accessToken);
+----
+
+You see we set the signing key with `setSigningKey` the library still skips the validation of the signature.
+
+It is not only limited to the traditional `alg: none` attack, but it also works with the `alg: HS256`.
+
+=== Conclusion
+
+When you have chosen a library to help dealing with JWT tokens make sure to:
+
+- use the correct method in your code when validating tokens.
+- add test cases and validate the algorithm confusion is not possible.
+- as a security team write a utility methods to be used by the teams which encapsulate the library to make sure the teams use the correct parsing logic.
+
+=== Alternative: Paseto
+
+The algorithm confusion is a real problem when dealing with JWTs it can be avoided by using PASETO (**P**latform-**A**gnostic **SE**curity **TO**kens), which is currently implemented in 10 programming languages.
+One of the drawbacks of using this method is that JWT is widely spread for example think about using OAuth, so it might not be the best solution to use.
+
+For more information take a look at the following video:
+
+video::RijGNytjbOI[youtube, height=480, width=100%]