CVE-2023-1699: Rapid7 Nexpose Auth Bypass Vulnerability

CVE-2023-1699 Overview

CVE-2023-1699 is a forced browsing vulnerability affecting Rapid7 Nexpose versions 6.6.186 and below. This authorization bypass flaw allows an attacker to manipulate URLs to forcefully browse to and access administrative pages without proper authentication. The vulnerability is classified as CWE-425 (Direct Request / Forced Browsing), which occurs when a web application does not properly restrict access to resources through URL manipulation.

Critical Impact

Unauthenticated attackers can bypass access controls and directly access administrative functionality in Rapid7 Nexpose, potentially leading to complete system compromise.

Affected Products

• Rapid7 Nexpose versions 6.6.186 and below
• All installations running vulnerable Nexpose versions with network-exposed interfaces

Discovery Timeline

• 2023-03-29 - Rapid7 releases security patch in version 6.6.187
• 2023-03-30 - CVE-2023-1699 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-1699

Vulnerability Analysis

This forced browsing vulnerability (CWE-425) exists in Rapid7 Nexpose's web application component, which fails to properly enforce authorization checks on administrative endpoints. Forced browsing attacks exploit inadequate access control mechanisms by allowing attackers to directly request URLs that should be restricted to authenticated or privileged users.

In the context of Nexpose, a vulnerability management platform that handles sensitive security scan data and infrastructure details, unauthorized access to administrative pages could expose critical vulnerability data, scan configurations, credentials used for authenticated scans, and system settings. The vulnerability requires no authentication or user interaction, making it particularly dangerous for internet-exposed or internally accessible Nexpose deployments.

Root Cause

The root cause of this vulnerability lies in insufficient authorization enforcement on administrative URL paths within the Nexpose web application. The application fails to verify that users requesting administrative endpoints have the appropriate permissions or authentication status before serving the requested content. This is a common web application security flaw where backend authorization checks are missing or can be bypassed through direct URL manipulation.

Attack Vector

The attack can be executed remotely over the network without requiring any authentication credentials or user interaction. An attacker with network access to a vulnerable Nexpose instance can craft HTTP requests targeting administrative endpoints that would normally require authentication. By directly navigating to these URLs or manipulating request parameters, the attacker bypasses the intended access control flow and gains unauthorized access to privileged functionality.

The exploitation mechanism involves identifying administrative URL patterns and directly requesting them, circumventing any client-side access restrictions. Since the server-side fails to properly validate authorization, these requests are processed as if they came from an authenticated administrative user. This could allow attackers to view sensitive vulnerability scan results, modify system configurations, or potentially leverage administrative functions for further compromise.

Detection Methods for CVE-2023-1699

Indicators of Compromise

• Unusual HTTP requests to administrative endpoints from unauthenticated sessions
• Access log entries showing direct navigation to /admin/ or similar privileged URL paths without prior authentication
• Multiple requests probing various administrative URLs from a single source IP
• Unexpected access to sensitive configuration or scan result pages without corresponding login events

Detection Strategies

• Monitor Nexpose access logs for requests to administrative endpoints that lack associated authentication events
• Implement web application firewall (WAF) rules to detect and alert on direct access attempts to privileged URL patterns
• Correlate authentication logs with administrative page access to identify authorization bypass attempts
• Deploy network intrusion detection signatures for forced browsing attack patterns against Nexpose

Monitoring Recommendations

• Enable comprehensive access logging on Nexpose and centralize logs for analysis
• Configure alerts for administrative endpoint access from non-administrative user sessions
• Implement anomaly detection for unusual URL access patterns or high volumes of 403/404 responses indicating reconnaissance
• Review authentication event correlation with sensitive page access on a regular basis

How to Mitigate CVE-2023-1699

Immediate Actions Required

• Upgrade Rapid7 Nexpose to version 6.6.187 or later immediately
• Restrict network access to Nexpose administrative interfaces to trusted IP ranges only
• Review access logs for evidence of exploitation prior to patching
• Implement additional network segmentation to limit exposure of Nexpose management interfaces

Patch Information

Rapid7 has addressed this vulnerability in Nexpose version 6.6.187, released on March 29, 2023. Organizations should upgrade to this version or later to remediate the forced browsing vulnerability. Detailed release notes are available in the Rapid7 Nexpose Release Notes.

Workarounds

• Implement network-level access controls to restrict access to Nexpose web interfaces from untrusted networks
• Deploy a reverse proxy or web application firewall in front of Nexpose to enforce additional access control checks
• Disable external network access to Nexpose and require VPN for remote administration
• Monitor and alert on any access attempts to administrative URLs until patching is complete

# Example: Restrict Nexpose access via iptables to trusted management network
iptables -A INPUT -p tcp --dport 3780 -s 10.10.10.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 3780 -j DROP