Security Experts:

Splunk Patches Information Theft and XSS Flaws

Splunk last week released an update for Splunk Enterprise to address an information theft bug and a persistent Cross Site Scripting (XSS) vulnerability.

Discovered last year by security researcher John Page (who goes by the online handle of hyp3rlinx), the information theft issue is tracked as CVE-2017-5607 and has been assessed a CVSS Base Score of 3.5. The vulnerability can be exploited by a remote attacker to siphon information from Splunk Enterprise when the user visits a malicious webpage.

In an advisory, the security researcher notes that an attacker exploiting this vulnerability could access data such as the currently logged in username and if remote user setting is enabled. With the username in hand, the attacker could either phish or brute force the Splunk Enterprise login.

The attacker can use JavaScript to exploit the issue, as the root cause of it is the global Window JS variable assignment of config?autoload=1 '$C', the security researcher notes in his advisory.

“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 an 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,” the researcher explains.

Splunk has confirmed that affected Splunk Enterprise versions include 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.

The security researcher discovered the bug in November 2016 and reported it to Splunk the same month. He received acknowledgement of the bug a couple of days later, but the patch was released only last week. The researcher published not only details pertaining to the vulnerability, but also proof-of-concept JavaScript code and a video to demonstrate the flaw.

The second vulnerability addressed in Splunk Enterprise last week was a persistent Cross Site Scripting in Splunk Web, which was found to allow an attacker to inject and store arbitrary script, but only if they are authenticated in Splunk web before exploiting the bug. Assessed with a CVSS Base Score of 6.6, the flaw impacts 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; and Splunk Light before 6.5.2.

Related: Splunk Unveils New Threat Detection, Analytics Offerings

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