CVE-2018-20698 in Search Guard Plugin
Summary
by MITRE
The floragunn Search Guard plugin before 6.x-16 for Kibana allows URL injection for login redirects on the login page when basePath is set.
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Analysis
by VulDB Data Team • 08/28/2023
The CVE-2018-20698 vulnerability affects the floragunn Search Guard plugin version 6.x-16 and earlier implementations for Kibana, presenting a significant security risk through improper input validation in the login redirect mechanism. This flaw specifically manifests when the basePath configuration parameter is enabled within Kibana, creating an avenue for malicious actors to manipulate URL redirections during authentication processes. The vulnerability stems from the plugin's failure to properly sanitize or validate redirect URLs, allowing attackers to inject arbitrary URLs that could be used to redirect users to malicious destinations.
The technical implementation of this vulnerability resides in the authentication flow where the plugin processes redirect parameters without adequate validation of the target URLs. When basePath is configured, the plugin constructs redirect URLs by concatenating user-provided parameters with hardcoded base paths, creating an injection point that can be exploited by attackers. This behavior violates security principles outlined in CWE-601, which addresses URL redirection vulnerabilities where applications redirect users to untrusted domains. The flaw essentially allows an attacker to craft malicious login redirect URLs that could lead to phishing attacks, credential theft, or other malicious activities.
The operational impact of this vulnerability extends beyond simple unauthorized access attempts, as it can be leveraged to create sophisticated social engineering campaigns. An attacker could manipulate the redirect parameter to send authenticated users to phishing sites that mimic legitimate Kibana interfaces, potentially capturing credentials or other sensitive information. The vulnerability is particularly dangerous in enterprise environments where Kibana is used for security monitoring and log analysis, as compromised authentication flows could provide attackers with access to critical system information. This type of attack aligns with techniques described in the ATT&CK framework under credential access and initial access phases, where attackers seek to establish persistent access through compromised authentication mechanisms.
Organizations should immediately upgrade to Search Guard plugin versions 6.x-16 or later where this vulnerability has been addressed through proper input validation and URL sanitization. The mitigation strategy should include implementing proper web application firewalls to monitor and filter suspicious redirect parameters, conducting thorough security assessments of all authentication flows, and ensuring that basePath configurations are properly validated. Additionally, network administrators should monitor for unusual redirect patterns in authentication logs and implement security controls that prevent external URL injection in authentication contexts. The vulnerability demonstrates the critical importance of input validation in security-critical components and highlights the need for comprehensive security testing of authentication mechanisms within enterprise applications.