CVE-2021-31602: Pentaho Authentication Bypass Vulnerability

CVE-2021-31602 Overview

CVE-2021-31602 is an authentication bypass vulnerability discovered in Hitachi Vantara Pentaho through version 9.1 and Pentaho Business Intelligence Server through 7.x. The vulnerability exists within the Security Model's Access Control layers, specifically in the applicationContext-spring-security.xml configuration file. The default configuration allows unauthenticated users with no prior knowledge of platform settings to extract sensitive information without possessing valid credentials.

Critical Impact

Unauthenticated attackers can bypass authentication controls and access sensitive platform information remotely without valid credentials, potentially exposing business intelligence data and system configurations.

Affected Products

• Hitachi Vantara Pentaho (through version 9.1)
• Hitachi Vantara Pentaho Business Intelligence Server (through version 7.x)

Discovery Timeline

• 2021-11-08 - CVE-2021-31602 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2021-31602

Vulnerability Analysis

This vulnerability is classified as an Authentication Bypass (CWE-287), which allows attackers to circumvent the security controls intended to protect sensitive resources. The flaw resides in the Spring Security configuration layer of the Pentaho platform, which is one of several access control mechanisms in the security model.

The vulnerability is exploitable remotely over the network without requiring any user interaction or prior authentication. Successful exploitation results in unauthorized access to confidential information, though it does not directly impact system integrity or availability. The attack requires low complexity, making it accessible to attackers with minimal technical expertise.

Root Cause

The root cause lies in the default configuration of the applicationContext-spring-security.xml file, which fails to properly enforce authentication requirements for certain endpoints. This misconfiguration in the Spring Security framework allows the security layer to be bypassed, enabling unauthenticated access to protected resources. The Security Model implements multiple layers of Access Control, but this particular layer's default settings are overly permissive.

Attack Vector

The attack vector is network-based, allowing remote exploitation. An attacker can target exposed Pentaho installations without requiring any authentication credentials or prior knowledge of the platform's configuration. The vulnerability can be exploited by crafting HTTP requests to specific endpoints that bypass the authentication checks defined in the Spring Security configuration.

The exploitation technique involves sending specially crafted requests to the Pentaho server that circumvent the authentication layer. Technical details and proof-of-concept information are available through the Packet Storm Security advisory.

Detection Methods for CVE-2021-31602

Indicators of Compromise

• Unusual HTTP requests to Pentaho endpoints from unauthenticated sources
• Access log entries showing successful responses to protected resources without valid session tokens
• Unexpected data extraction or information disclosure events in Pentaho server logs
• Network traffic patterns indicating reconnaissance or enumeration of Pentaho services

Detection Strategies

• Monitor web server access logs for requests to sensitive Pentaho endpoints without proper authentication headers
• Implement network-level detection for HTTP traffic patterns associated with authentication bypass attempts
• Deploy web application firewall (WAF) rules to detect and block anomalous requests to Spring Security protected resources
• Use SentinelOne Singularity XDR to correlate endpoint activity with network traffic for comprehensive threat detection

Monitoring Recommendations

• Enable detailed access logging for all Pentaho Business Intelligence Server endpoints
• Configure alerting for failed and successful authentication events, particularly focusing on access without valid credentials
• Implement real-time monitoring of the applicationContext-spring-security.xml configuration file for unauthorized modifications
• Review Pentaho application logs regularly for signs of information extraction or unauthorized access patterns

How to Mitigate CVE-2021-31602

Immediate Actions Required

• Restrict network access to Pentaho installations using firewall rules to limit exposure
• Review and harden the applicationContext-spring-security.xml configuration to enforce proper authentication
• Implement network segmentation to isolate Pentaho servers from untrusted networks
• Enable comprehensive logging and monitoring on affected systems

Patch Information

Hitachi has acknowledged this security issue. Organizations should consult the Hitachi Security Information Portal for official security advisories and patch availability. It is recommended to upgrade to the latest supported version of Pentaho that addresses this vulnerability.

Workarounds

• Modify the applicationContext-spring-security.xml configuration to require authentication for all sensitive endpoints
• Place affected Pentaho instances behind a reverse proxy with additional authentication requirements
• Implement IP-based access controls to restrict access to trusted networks only
• Deploy a Web Application Firewall (WAF) with rules to detect and block authentication bypass attempts

# Configuration example - Restrict network access to Pentaho server
# Add firewall rules to limit access to trusted IP ranges only
iptables -A INPUT -p tcp --dport 8080 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -j DROP

# Review Spring Security configuration
cat /pentaho/server/pentaho-server/pentaho-solutions/system/applicationContext-spring-security.xml