CVE-2023-34056: VMware vCenter Server Info Disclosure

CVE-2023-34056 Overview

VMware vCenter Server contains a partial information disclosure vulnerability that allows unauthorized data access. A malicious actor with non-administrative privileges to vCenter Server may leverage this issue to access unauthorized data, potentially exposing sensitive configuration or operational information within the virtualization management infrastructure.

Critical Impact

Attackers with low-privilege access to vCenter Server can access unauthorized data, potentially exposing sensitive virtualization infrastructure information.

Affected Products

• VMware vCenter Server 7.0 (all versions through Update 3n)
• VMware vCenter Server 8.0 (all versions through Update 1d)
• VMware vCenter Server 8.0 Update 1 series (8.0a, 8.0b, 8.0c, Update 1a through Update 1d)

Discovery Timeline

• October 25, 2023 - CVE-2023-34056 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2023-34056

Vulnerability Analysis

This information disclosure vulnerability in VMware vCenter Server stems from insufficient access control mechanisms that fail to properly restrict data access based on user privilege levels. The vulnerability is categorized under CWE-922 (Insecure Storage of Sensitive Information), indicating that sensitive data may be accessible to users who should not have permission to view it.

The attack requires network access and low-privilege authentication to the vCenter Server environment. Once authenticated, an attacker can leverage the flaw to access data beyond their authorized scope. While the confidentiality impact is limited rather than complete, the vulnerability still poses a significant risk in enterprise environments where vCenter Server manages critical virtualization infrastructure.

Root Cause

The root cause of CVE-2023-34056 lies in improper access control validation within vCenter Server's data access mechanisms. The platform fails to adequately enforce privilege boundaries, allowing authenticated users with non-administrative roles to query or retrieve information that should be restricted to higher-privilege accounts. This represents a breakdown in the principle of least privilege, where the application does not properly segregate data access based on the authenticated user's authorization level.

Attack Vector

The vulnerability is exploited over the network by an authenticated user with legitimate but non-administrative access to the vCenter Server. The attacker does not require user interaction or special conditions to exploit this flaw. The attack flow involves:

1. An attacker authenticates to vCenter Server with valid low-privilege credentials
2. The attacker crafts requests to access data or endpoints that should require higher privileges
3. Due to insufficient access control validation, the server returns unauthorized information
4. The attacker can collect sensitive data about the virtualization environment

Since no public proof-of-concept exploits have been published for this vulnerability, specific technical exploitation details are not publicly documented. Organizations should consult the VMware Security Advisory VMSA-2023-0023 for additional technical context.

Detection Methods for CVE-2023-34056

Indicators of Compromise

• Unusual data access patterns from low-privilege user accounts in vCenter Server audit logs
• API requests attempting to access administrative or restricted endpoints from non-administrative sessions
• Increased query volume or atypical data retrieval behavior from authenticated users
• Authentication events followed by access attempts to configuration or infrastructure metadata

Detection Strategies

• Enable and review vCenter Server audit logging for anomalous data access patterns
• Monitor API call patterns and flag requests from non-admin accounts attempting to access privileged data
• Implement user behavior analytics to detect deviations from normal access patterns for each user role
• Cross-reference authentication logs with data access logs to identify privilege boundary violations

Monitoring Recommendations

• Configure SIEM rules to alert on vCenter Server API access anomalies from low-privilege accounts
• Establish baseline behavior for each user role and alert on deviations
• Monitor for bulk data extraction or enumeration attempts from authenticated sessions
• Review vCenter Server logs regularly for signs of information gathering activities

How to Mitigate CVE-2023-34056

Immediate Actions Required

• Apply the latest security patches from VMware for vCenter Server versions 7.0 and 8.0
• Review and audit all user accounts with access to vCenter Server, removing unnecessary access
• Implement network segmentation to limit access to vCenter Server management interfaces
• Enable comprehensive logging and monitoring on vCenter Server instances

Patch Information

VMware has released patches to address this vulnerability as detailed in VMware Security Advisory VMSA-2023-0023. Organizations running affected versions of vCenter Server 7.0 or 8.0 should update to the latest patched releases immediately. The advisory provides specific version information and download links for remediated software.

Workarounds

• Restrict network access to vCenter Server management interfaces using firewall rules
• Implement strict role-based access control, ensuring users have only minimum necessary privileges
• Isolate vCenter Server on dedicated management networks separate from general user networks
• Consider disabling unnecessary features or API endpoints until patches can be applied

# Example: Restrict vCenter access via iptables
# Allow only management network to access vCenter
iptables -A INPUT -p tcp --dport 443 -s 10.0.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP

# Review current vCenter user permissions
# Connect to vCenter via PowerCLI and audit roles
# Get-VIPermission | Where-Object {$_.Role -ne "Admin"} | Export-Csv permissions_audit.csv