CVE-2023-20855 Overview
VMware vRealize Orchestrator contains an XML External Entity (XXE) vulnerability that poses a significant risk to enterprise automation infrastructure. A malicious actor with non-administrative access to vRealize Orchestrator may be able to use specially crafted input to bypass XML parsing restrictions, leading to access to sensitive information or possible escalation of privileges.
Critical Impact
Authenticated attackers can exploit improper XML parsing to access sensitive data and potentially escalate privileges within VMware vRealize Orchestrator and vRealize Automation environments.
Affected Products
- VMware vRealize Orchestrator
- VMware vRealize Automation
Discovery Timeline
- February 22, 2023 - CVE-2023-20855 published to NVD
- March 17, 2025 - Last updated in NVD database
Technical Details for CVE-2023-20855
Vulnerability Analysis
This vulnerability stems from improper handling of XML input within VMware vRealize Orchestrator. The XXE vulnerability (CWE-611) allows authenticated users with non-administrative privileges to craft malicious XML payloads that can bypass the intended XML parsing restrictions. When the vulnerable component processes these specially crafted XML documents, external entity references are resolved, potentially exposing sensitive system information or enabling further exploitation.
The attack requires network access and valid credentials with at least basic (non-administrative) access to vRealize Orchestrator. Once authenticated, an attacker can leverage the XXE flaw to read arbitrary files from the server, perform server-side request forgery (SSRF), or potentially escalate privileges within the environment.
Root Cause
The root cause of CVE-2023-20855 is improper configuration of XML parsers within vRealize Orchestrator that fail to disable external entity resolution. When XML input is processed without properly restricting Document Type Definitions (DTDs) and external entity references, attackers can inject malicious entity declarations that reference external resources or local files.
This misconfiguration allows the XML parser to resolve external entities during document processing, which can lead to:
- Disclosure of local file contents
- Server-side request forgery to internal services
- Denial of service through entity expansion attacks
- Potential privilege escalation through exposed credentials or configuration data
Attack Vector
The attack vector for this vulnerability is network-based, requiring the attacker to have authenticated access to the vRealize Orchestrator interface. The exploitation flow typically involves:
- An attacker authenticates to vRealize Orchestrator with valid non-administrative credentials
- The attacker crafts a malicious XML payload containing external entity declarations
- The payload is submitted through a vulnerable endpoint that processes XML input
- The XML parser resolves the external entities, executing the attacker's intended action
- Sensitive data is returned to the attacker or privileges are escalated
XXE attacks typically involve injecting entity declarations that reference local files (such as /etc/passwd on Linux systems) or external URLs. The vulnerability allows bypassing XML parsing restrictions that should prevent such entity resolution.
Detection Methods for CVE-2023-20855
Indicators of Compromise
- Unusual XML-based requests containing DOCTYPE declarations or ENTITY definitions in vRealize Orchestrator logs
- Unexpected file access attempts from the vRealize Orchestrator service account
- Network connections from vRealize Orchestrator to unexpected internal or external destinations
- Authentication events followed by suspicious XML parsing errors or exceptions
Detection Strategies
- Monitor vRealize Orchestrator application logs for XML parsing exceptions or DTD-related warnings
- Implement network-level detection for outbound connections from vRealize Orchestrator to unusual destinations
- Deploy file integrity monitoring on sensitive configuration files that could be targeted via XXE
- Enable audit logging for all authenticated sessions and correlate with XML-based API calls
Monitoring Recommendations
- Configure SIEM alerts for patterns indicative of XXE exploitation attempts in HTTP request payloads
- Monitor for privilege escalation events following non-administrative user authentication
- Review access logs for repeated attempts to access XML-processing endpoints
- Implement anomaly detection for unusual data exfiltration patterns from vRealize infrastructure
How to Mitigate CVE-2023-20855
Immediate Actions Required
- Apply the security patches referenced in VMware Security Advisory VMSA-2023-0005 immediately
- Review and audit all non-administrative user accounts with access to vRealize Orchestrator
- Implement network segmentation to limit exposure of vRealize Orchestrator to trusted networks only
- Enable enhanced logging on vRealize Orchestrator to detect potential exploitation attempts
Patch Information
VMware has released security patches addressing this vulnerability. Administrators should consult the VMware Security Advisory VMSA-2023-0005 for specific patch versions and upgrade instructions applicable to their deployment.
The advisory provides detailed guidance on affected versions and the corresponding fixed releases for both vRealize Orchestrator and vRealize Automation.
Workarounds
- Restrict network access to vRealize Orchestrator management interfaces using firewall rules
- Implement Web Application Firewall (WAF) rules to filter XML payloads containing DOCTYPE or ENTITY declarations
- Review and minimize the number of users with access to vRealize Orchestrator
- Consider temporarily disabling non-essential XML-processing functionality until patches can be applied
- Implement additional authentication controls such as multi-factor authentication for vRealize access
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
