CVE-2023-20884: VMware Identity Manager Info Disclosure

CVE-2023-20884 Overview

CVE-2023-20884 is an insecure redirect vulnerability affecting VMware Workspace ONE Access and VMware Identity Manager. An unauthenticated malicious actor may be able to redirect a victim to an attacker-controlled domain due to improper path handling, potentially leading to sensitive information disclosure. This vulnerability is classified as CWE-601 (URL Redirection to Untrusted Site, also known as "Open Redirect").

Critical Impact

Unauthenticated attackers can exploit improper path handling to redirect users to malicious domains, enabling phishing attacks, credential theft, and sensitive information disclosure.

Affected Products

• VMware Workspace ONE Access
• VMware Identity Manager (versions 3.3.6, 3.3.7)
• VMware Identity Manager Connector
• VMware Cloud Foundation
• Deployments on Linux and Windows platforms

Discovery Timeline

• 2023-05-30 - CVE-2023-20884 published to NVD
• 2025-01-10 - Last updated in NVD database

Technical Details for CVE-2023-20884

Vulnerability Analysis

This open redirect vulnerability exists within VMware's identity and access management products due to improper validation of URL path parameters during authentication flows. The vulnerability allows attackers to craft malicious URLs that appear legitimate to users but ultimately redirect them to attacker-controlled domains after interacting with the vulnerable VMware service.

The core issue stems from insufficient input validation on redirect parameters within the authentication workflow. When users authenticate through VMware Workspace ONE Access or Identity Manager, the application processes redirect URLs to return users to their intended destination after successful authentication. However, the improper path handling allows attackers to manipulate these redirect parameters.

Root Cause

The vulnerability is rooted in CWE-601: URL Redirection to Untrusted Site (Open Redirect). The affected VMware products fail to properly validate and sanitize redirect URLs during the authentication process. This allows attackers to inject external URLs that bypass the intended redirect validation logic, causing the application to redirect authenticated users to arbitrary external domains.

The improper path handling specifically relates to how the application parses and validates the redirect destination parameter. Attackers can use URL encoding, path traversal sequences, or other manipulation techniques to craft redirect URLs that pass initial validation checks but ultimately resolve to malicious external sites.

Attack Vector

The attack requires network access and user interaction. An attacker crafts a malicious URL targeting the vulnerable VMware endpoint, embedding an attacker-controlled redirect destination within the URL parameters. The attack flow typically involves:

1. The attacker creates a specially crafted URL pointing to a legitimate VMware Workspace ONE Access or Identity Manager endpoint
2. The malicious URL contains a manipulated redirect parameter that points to an attacker-controlled domain
3. The attacker distributes this URL through phishing emails, compromised websites, or social engineering
4. When a victim clicks the link, they see a legitimate VMware login page, building false trust
5. After authentication (or even without it in some scenarios), the victim is redirected to the attacker's malicious site
6. The attacker can then harvest credentials, session tokens, or other sensitive information

The attack surface includes phishing campaigns, credential harvesting operations, and man-in-the-middle attacks where attackers intercept sensitive data by masquerading as trusted VMware services.

Detection Methods for CVE-2023-20884

Indicators of Compromise

• Unusual redirect URLs in VMware Workspace ONE Access or Identity Manager logs containing external domains
• Authentication requests with suspicious or malformed redirect parameters
• Reports from users of unexpected redirects after interacting with VMware authentication pages
• Increased phishing activity targeting users of VMware identity services

Detection Strategies

• Monitor web application logs for requests to authentication endpoints containing redirect parameters pointing to external domains
• Implement URL filtering and inspection rules to detect malformed or suspicious redirect parameters
• Deploy network monitoring to identify traffic patterns indicative of open redirect exploitation
• Configure SentinelOne Singularity to detect and alert on suspicious browser redirect patterns and potential phishing payloads

Monitoring Recommendations

• Enable verbose logging on VMware Workspace ONE Access and Identity Manager instances
• Implement real-time alerting for authentication anomalies and unusual redirect patterns
• Monitor for bulk redirect attempts or automated scanning activity targeting authentication endpoints
• Review referrer headers in web logs to identify suspicious traffic sources

How to Mitigate CVE-2023-20884

Immediate Actions Required

• Apply the security patches referenced in VMware Security Advisory VMSA-2023-0011 immediately
• Review and audit all VMware Workspace ONE Access and Identity Manager deployments for vulnerable versions
• Implement web application firewall (WAF) rules to filter malicious redirect parameters
• Educate users about phishing risks and the importance of verifying URLs before entering credentials

Patch Information

VMware has released security updates to address this vulnerability. Administrators should consult the VMware Security Advisory VMSA-2023-0011 for specific patch versions and upgrade instructions. The advisory provides detailed remediation guidance for all affected products including VMware Workspace ONE Access, Identity Manager, Identity Manager Connector, and Cloud Foundation deployments.

Workarounds

• Implement strict URL allowlisting for redirect destinations at the WAF or reverse proxy level
• Configure Content Security Policy (CSP) headers to restrict allowed redirect destinations
• Deploy additional authentication factors to reduce the impact of potential credential theft
• Consider network segmentation to limit exposure of identity management systems to untrusted networks

# Example WAF rule concept for blocking external redirects
# Deny requests with redirect parameters containing external URLs
# Adjust the pattern to match your specific deployment
# SecRule ARGS:redirect "@rx ^https?:\/\/(?!your-trusted-domain\.com)" "id:1,phase:2,deny,status:403,msg:'Blocked potential open redirect'"