CVE-2016-4856 in Splunk
Summary
by MITRE
Cross-site scripting vulnerability in Splunk Enterprise 6.3.x prior to 6.3.5 and Splunk Light 6.3.x prior to 6.3.5 allows attacker with administrator rights to inject arbitrary web script or HTML via unspecified vectors.
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Analysis
by VulDB Data Team • 12/23/2020
The CVE-2016-4856 vulnerability represents a critical cross-site scripting flaw within Splunk Enterprise and Splunk Light versions 6.3.x prior to 6.3.5. This vulnerability specifically targets the web interface components of these security information and event management platforms, creating a significant risk for organizations that rely on Splunk for log analysis and security monitoring. The flaw arises from inadequate input validation and output encoding mechanisms within the Splunk web application, allowing malicious actors with administrative privileges to execute arbitrary scripts within the context of other users' browsers. The vulnerability is particularly concerning because it requires only administrative access, which is often considered a privileged position within security infrastructures, making exploitation more feasible in environments where administrative accounts are compromised or where attackers have already gained elevated privileges.
The technical nature of this vulnerability aligns with CWE-79, which classifies cross-site scripting as a weakness where untrusted data is improperly incorporated into web page content without proper sanitization or encoding. The flaw manifests when administrators interact with specific web interface elements that process user input without adequate validation, creating an attack surface where malicious scripts can be injected and subsequently executed in the browsers of other users who access the affected Splunk instances. This vulnerability operates through unspecified vectors, indicating that the attack could potentially occur through multiple pathways within the Splunk web interface, including but not limited to configuration settings, search interfaces, or administrative panels where user input is processed. The lack of specific vector details suggests that the vulnerability may be widespread across multiple components of the Splunk web application, making it particularly dangerous as attackers can exploit various entry points to deliver malicious payloads.
The operational impact of CVE-2016-4856 extends beyond simple script execution, as it can enable sophisticated attack chains that leverage the administrative privileges of the compromised Splunk instance. Attackers could potentially use this vulnerability to steal session cookies, redirect users to malicious sites, deface web interfaces, or even establish persistent backdoors within the Splunk environment. Given that Splunk is commonly used for security monitoring and log aggregation, an attacker who successfully exploits this vulnerability could gain access to sensitive security data, potentially compromising the integrity of the entire security infrastructure. The vulnerability also creates opportunities for privilege escalation attacks where an attacker could use the XSS capability to manipulate administrative functions, access restricted data, or modify system configurations that could affect the broader network security posture. This risk is exacerbated by the fact that Splunk administrators often have access to comprehensive security event data, making the potential impact of such an attack significant for organizations relying on Splunk for security operations.
Organizations should prioritize immediate remediation through patching to address CVE-2016-4856, as the vulnerability requires only administrative access to exploit, making it particularly dangerous in environments where administrative privileges are compromised. The recommended mitigation strategy involves upgrading to Splunk Enterprise 6.3.5 or later versions, or Splunk Light 6.3.5 or later, which contain the necessary security fixes to prevent the XSS injection vectors. Additionally, organizations should implement network segmentation and access controls to limit administrative access to Splunk instances, reducing the attack surface for potential exploitation. Security monitoring should be enhanced to detect unusual administrative activities that might indicate compromise of administrative accounts, and regular security assessments should be conducted to verify that no malicious scripts have been injected into the Splunk environment. The vulnerability also highlights the importance of implementing defense-in-depth strategies, including web application firewalls and content security policies that can provide additional protection layers against XSS attacks, particularly in environments where Splunk is exposed to untrusted network traffic. This vulnerability demonstrates the critical importance of maintaining up-to-date security patches and the potential consequences of running outdated software versions in security-critical infrastructure components.