Skip to main content

Tomcat7 session fixation and session listener

Ran into an interesting issue. We use flash uploader in our web ui for browsers that dont support html5 and flash has a problem that each request it makes to server has a new session because it wont send any cookies back to server. The only way to circumvent around this is to send original sessionId as a post parameter and on server cache all the sessions in tomcat memory and then join this new session to the original session using sessionid coming in post.

Anyways long story short we updated to tomcat7 and suddenly one of our feature that allows us to impersonate a user broke.  Finally nailed it to  a security fix in tomcat7 that will renew sessionId on basic authentication but the issue is that to do flash based file upload we relied on HttpSessionListener.sessionCreated to cache all sessions by sessionId.  And when  tomcat7 was renewing sessionId  it was not calling  the sessionCreated event for the new session. There were two ways to solve it:

1) Disable session fixation security fix by adding  the below valve to context.xml . I did not chose to do this as it would make tomcat less secure.

<Valve className="org.apache.catalina.authenticator.BasicAuthenticator"  changeSessionIdOnAuthentication="false"/>

2) Extract the code in HttpSessionListener.sessionCreated to a common method and call it manually during impersonation.  I chose this way for now as its more secure.  In future when tomcat fixes this bug I will remove this code.

Comments

Popular posts from this blog

RabbitMQ java clients for beginners

Here is a sample of a consumer and producer example for RabbitMQ. The steps are
Download ErlangDownload Rabbit MQ ServerDownload Rabbit MQ Java client jarsCompile and run the below two class and you are done.
This sample create a Durable Exchange, Queue and a Message. You will have to start the consumer first before you start the for the first time.

For more information on AMQP, Exchanges, Queues, read this excellent tutorial
http://blogs.digitar.com/jjww/2009/01/rabbits-and-warrens/

+++++++++++++++++RabbitMQProducer.java+++++++++++++++++++++++++++
import com.rabbitmq.client.Connection; import com.rabbitmq.client.Channel; import com.rabbitmq.client.*; public class RabbitMQProducer { public static void main(String []args) throws Exception { ConnectionFactory factory = new ConnectionFactory(); factory.setUsername("guest"); factory.setPassword("guest"); factory.setVirtualHost("/"); factory.setHost("127.0.0.1"); factory.setPort(5672); Conne…

Logging to Graphite monitoring tool from java

We use Graphite as a tool for monitoring some stats and watch trends. A requirement is to monitor impact of new releases as build is deployed to app nodes to see if things like
1) Has the memcache usage increased.
2) Has the no of Java exceptions went up.
3) Is the app using more tomcat threads.
Here is a screenshot

We changed the installer to log a deploy event when a new build is deployed. I wrote a simple spring bean to log graphite events using java. Logging to graphite is easy, all you need to do is open a socket and send lines of events.
import org.slf4j.Logger;import org.slf4j.LoggerFactory; import java.io.OutputStreamWriter; import java.io.Writer; import java.net.Socket; import java.util.HashMap; import java.util.Map; public class GraphiteLogger { private static final Logger logger = LoggerFactory.getLogger(GraphiteLogger.class); private String graphiteHost; private int graphitePort; public String getGraphiteHost() { return graphiteHost; } public void setGraphite…

Jersey posting multipart data

This took me sometime to figure out mostly it was because I was only including jersey-multipart-1.6.jar but I was not including mimepull-1.3.jar.

So the intent is to upload a file using REST api and we need pass meta attributes in addition to uploading the file. Also the intent is to stream the file instead of first storing it on the local disk. Here is some sample code.
@Path("/upload-service") public class UploadService { @Context protected HttpServletResponse response; @Context protected HttpServletRequest request; @POST @Consumes(MediaType.MULTIPART_FORM_DATA) @Produces(MediaType.APPLICATION_JSON) public String uploadFile(@PathParam("fileName") final String fileName, @FormDataParam("workgroupId") String workgroupId, @FormDataParam("userId") final int userId, @FormDataParam("content") final InputStream content) throws JSONException { //.......Upload the file to S3 or netapp or any storage service } }
Now to tes…