10 Replies Latest reply on Jan 15, 2018 5:51 AM by Tomaz Cerar

    Path traversal security issue on Web application running with Wildfly 9.0.1

    Laurent Roussel Newbie

      Hi,

       

      A Path traversal security vulnerability has been detected on an application of my project. It is a Java web application that integrates the Spring framework and runs on a Wildfly server. An apache httpd server is positioned upstream with mod_cluster module enabled. Requests are transferred from apache to Wildfly in ajp by mod_cluster.

       

      The versions of the components used are as follows:

      Wildfly: 9.0.1 (undertow: 1.2.9)

      Spring (core, MVC, web, etc.): 4.0.9

      Apache httpd: 2.4.6

      modcluster: 1.3.0

       

      The security breach is reproduced by sending an http GET request with an url that has the following pattern: https://<hostname>/<web_app_context>/public/..%5c..%5c ..% 5c..% 5c ..% 5c ..% 5c ..% 5c ..% 5c / etc / passwd

       

      The answer obtained is the contents of the file corresponding to the path in the url (here /etc/passwd).

       

      I have noticed two behaviors quiet strange related to wildfly:

      • The first one is that the component io.undertow.servlet.spec.ServletContextImpl with the method getResourceAsStream can return a resource that is outside the root folder of the web app  with relative path (..\..\..\..\..\..\..\..\/etc/passwd). If I correctly understand the JSR Servlet it should not be the case and it could be a security issue on the server. For me the problem is located in the method getResource of the component org.wildfly.extension.undertow.deployment.ServletResourceManager that doesn't do any control on relative paths that go outside of the root folder of the web app.

       

      • The second one is that the Ajp connector with the component io.undertow.server.protocol.ajp.AjpRequestParser, always decode the encoded slash and backslash. It's not the case for Http Connector with HttpRequestParser that prevents these operations with URLUtils (and the option ALLOW_ENCODED_SLASH that is by default set to false). Is it an expected behavior ? Should not the method and option be taken into account for all connectors?

       

      Thanks for your help and answers

       

      Best regards

       

      Laurent

        • 1. Re: Path traversal security issue on Web application running with Wildfly 9.0.1
          jaikiran pai Master

          AFAIK, this has been fixed in later versions of Undertow and WildFly. Have you tried this against the latest versions?

          • 2. Re: Path traversal security issue on Web application running with Wildfly 9.0.1
            jaikiran pai Master

            Either way, mentioning swd847 just in case this still is an issue.

            • 3. Re: Path traversal security issue on Web application running with Wildfly 9.0.1
              Laurent Roussel Newbie

              Hi Jaikiran,

               

              Thanks a lot for your answer.

               

              I'm going to perform the test on a more recent version.

              • 4. Re: Path traversal security issue on Web application running with Wildfly 9.0.1
                Laurent Roussel Newbie

                Hi Jaikiran and swd847,

                 

                I have done some tests with Wildfly 11 and I get the same issue. I can get files of my VM that are outside of my web application in the http response.

                 

                The code related to the two "strange" behaviors I found is still present in Wildfly 11.

                 

                Best regards,

                 

                Laurent

                • 5. Re: Path traversal security issue on Web application running with Wildfly 9.0.1
                  Stuart Douglas Master

                  The first issue is resolved, see UNDERTOW-666 servlet forward can access filesystem outside base path · undertow-io/undertow@432f062 · GitHub  .

                   

                  Looking at the code it seems like ALLOW_ENCODED_SLASH might still be an issue for the AJP parser, can you file an Undertow JIRA?

                  • 6. Re: Path traversal security issue on Web application running with Wildfly 9.0.1
                    jaikiran pai Master

                    lroussel35  wrote:

                     

                     

                     

                    I have done some tests with Wildfly 11 and I get the same issue. I can get files of my VM that are outside of my web application in the http response.

                     

                    The code related to the two "strange" behaviors I found is still present in Wildfly 11.

                     

                    Is this reproducible only when AJP is involved? How do you fire off those requests, using curl? Finally, you are sure this is WildFly 11? I tried reproducing this and haven't been able to so far.

                    • 7. Re: Path traversal security issue on Web application running with Wildfly 9.0.1
                      Laurent ROUSSEL Newbie

                      Hi jaikiran and swd847

                       

                      And thank you for your answers.

                       

                      Ok I'm going to create a dedicated Jira for the AJP Parser.

                       

                      Concerning the first issue I mentionned, I think it's a different problem than the one described in UNDERTOW-666. The classes involved to get the resource requested seems to be different. I confirmed that the tests have well been done on Wildfly 11.

                       

                      When I debug the source code, it's the following stack that provides the resource:

                          ServletResourceManager.getResource(String) line: 80 

                          CachingResourceManager.getResource(String) line: 114 

                          CachingResourceManager.getResource(String) line: 32 

                          ServletContextImpl.getResourceAsStream(String) line: 307 

                          ServletContextResource.getInputStream() line: 139   

                          ResourceHttpRequestHandler.writeContent(HttpServletResponse, Resource) line: 384 

                          ResourceHttpRequestHandler.handleRequest(HttpServletRequest, HttpServletResponse) line: 160 

                          HttpRequestHandlerAdapter.handle(HttpServletRequest, HttpServletResponse, Object) line: 51

                          DispatcherServlet.doDispatch(HttpServletRequest, HttpServletResponse) line: 938 

                          DispatcherServlet.doService(HttpServletRequest, HttpServletResponse) line: 870

                          DispatcherServlet(FrameworkServlet).processRequest(HttpServletRequest, HttpServletResponse) line: 961

                          DispatcherServlet(FrameworkServlet).doGet(HttpServletRequest, HttpServletResponse) line: 852 

                       

                      And the problem seems to be  localised in the method org.wildfly.extension.undertow.deployment.ServletResourceManager.getResource.

                       

                          @Override

                          public Resource getResource(final String path) throws IOException {

                              Resource res = deploymentResourceManager.getResource(path);

                              if (res != null) {

                                  return new ServletResource(this, res);

                              }

                              String p = path;

                              if (p.startsWith("/")) {

                                  p = p.substring(1);

                              }

                              if (overlays != null) {

                                  for (VirtualFile overlay : overlays) {

                                      VirtualFile child = overlay.getChild(p);

                                      if (child.exists()) {

                                          return new ServletResource(this, new VirtualFileResource(overlay.getPhysicalFile(), child, path));

                                      }

                                  }

                              }

                              for (int i = 0; i < externalOverlays.length; ++i) {

                                  ResourceManager manager = externalOverlays[i];

                                  res = manager.getResource(path);

                                  if(res != null) {

                                      return res;

                                  }

                              }

                              return null;

                       

                          }

                       

                      In my case, there is an overlay (/content/secu-1.0.0-SNAPSHOT.war/WEB-INF/lib/springfox-swagger-ui-2.2.2.jar/META-INF/)   and  it's the virtual file corresponding to the overlay that provides the file of the resource specified in the url.

                       

                      I send you the code source to reproduce the issue.

                       

                      To facilitate the reproduction, I have activated the option ALLOW_ENCODED_SLASH on the http connector.

                       

                      In my environment, with the request  http://<hostname>:8080/secu-1.0.0-SNAPSHOT/..%5c..%5c..%5c..%5c..%5c..%5c..%5c..%5c/etc/passwd, I get the /etc/passwd file of the VM.

                       

                      Best regards,

                       

                      Laurent

                      • 8. Re: Path traversal security issue on Web application running with Wildfly 9.0.1
                        Lapsang Souchong Newbie

                        Hello,

                         

                        I am a security manager and our team has focused on this item/subject.

                         

                        We lead a study based on the "Proof Of Concept" sent in last exchange (secu.zip from Laurent Roussel) and it seems to be averate. I push you our summary about this weakness.

                         

                        How is it possible to push this subject quickly ? (jaikiran, swd847, redhat assistance ?)

                         

                        VULNERABILITY MANAGEMENT :

                        Title

                        Path traversal in wildfly application server (undertow)

                        Discovery date

                        14/12/2017

                         

                        RISK :

                        Breach of data confidentiality

                         

                        AFFECTED SYSTEM :

                        Wildfly  : all versions (undertow) ?

                         

                        SUMMARY :

                        A team has discovered a "Path traversal" security weakness on Wildfly application servers. This vulnerability is related to an application server vulnerability that allows access to static files stored outside the application context of the web application.

                         

                        By manipulating URLs that reference files with “dot-dot-slash (../)” sequences and its variations, it may be possible to access arbitrary files stored on file system including application source code or configuration and critical system files. This vulnerability of the component "ServletResourceManager" is exploitable thanks to a too permissive implementation of AJP connector (component AjpRequestParser) which interprets the characters slash / anti-slash encoded in the url.

                         

                        SOLUTION :

                        It seems that no security patch is released to date. Could you confirm or make recommandations ?

                         

                        TEMPORARY BYPASS :

                        The team advocates:

                        • Problem remediation :
                          • use the http connector of the wildfly application server instead of the AJP connector. The http connector is implemented with protection for this type of request.
                          • without correcting the vulnerability, using spring MVC (version 4.3 or 5.x) to access the resources prevents exploiting the vulnerability.
                        • Mitigation :
                          • check the presence of an application firewall as well as the configuration of the path traversal rules
                          • limit the application server launch rights as much as possible and verify the rights applied to the files on the application server. An OS hardening operation of this type will limit impacts in case of exploitation.
                        • 9. Re: Path traversal security issue on Web application running with Wildfly 9.0.1
                          jaikiran pai Master

                          lapsang, thank you for the detailed explanation. Can you please follow the steps noted here Security Contacts and Procedures - Red Hat Customer Portal  to take this further?

                          • 10. Re: Path traversal security issue on Web application running with Wildfly 9.0.1
                            Tomaz Cerar Master

                            Fix was already committed to undertow as well as included in WildFly.