CVE-2018-18850 in Octopus Deploy
Summary
by MITRE
In Octopus Deploy 2018.8.0 through 2018.9.x before 2018.9.1, an authenticated user with permission to modify deployment processes could upload a maliciously crafted YAML configuration, potentially allowing for remote execution of arbitrary code, running in the same context as the Octopus Server (for self-hosted installations by default, SYSTEM).
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 06/03/2023
The vulnerability CVE-2018-18850 represents a critical security flaw in Octopus Deploy versions ranging from 2018.8.0 through 2018.9.x prior to 2018.9.1. This issue specifically targets the deployment process configuration handling mechanism within the Octopus Server software, which is widely used for automating software deployments across various environments. The vulnerability exists in the YAML parsing and processing functionality that allows users to define deployment processes and configurations. The flaw stems from insufficient input validation and sanitization when processing YAML files that are uploaded as part of deployment process definitions. This particular vulnerability falls under the CWE-774 category of inadequate input validation and is classified as a code injection vulnerability within the ATT&CK framework under the technique of Command and Scripting Interpreter. The vulnerability is particularly dangerous because it requires only authenticated access with specific permissions, making it exploitable by users who already have legitimate access to the system.
The technical implementation of this vulnerability occurs when an authenticated user with permission to modify deployment processes uploads a maliciously crafted YAML configuration file. The Octopus Server processes this YAML file without proper validation of the content structure, allowing specially crafted YAML that contains executable code or references to external resources that could be interpreted and executed by the server. The YAML parsing mechanism fails to properly sanitize or validate the input, creating a path for arbitrary code execution. When the server processes the malicious YAML, it can execute commands with the same privileges as the Octopus Server process itself, which by default runs with SYSTEM-level privileges in self-hosted installations. This privilege escalation allows the attacker to gain full control over the deployment server and potentially access other systems connected to the deployment infrastructure. The vulnerability demonstrates a classic insecure deserialization issue where the server blindly trusts the input structure without proper security checks.
The operational impact of this vulnerability is severe and multifaceted, affecting organizations that rely on Octopus Deploy for their software deployment automation. Attackers who can exploit this vulnerability can execute arbitrary code on the deployment server, potentially leading to complete system compromise, data exfiltration, or disruption of deployment operations. The default SYSTEM-level execution context provides attackers with extensive privileges to modify or delete deployment configurations, access sensitive deployment artifacts, and potentially move laterally within the network infrastructure. Organizations using self-hosted Octopus Deploy installations face the highest risk as these servers typically have elevated privileges and access to critical system resources. The vulnerability also impacts the integrity of the deployment pipeline, as attackers could modify deployment processes to inject malicious code into production deployments, potentially compromising the security of deployed applications. This vulnerability directly violates the principle of least privilege and can lead to significant business disruption and security incidents.
Organizations should immediately apply the patch released in version 2018.9.1 to address this vulnerability, as no effective workarounds exist for this particular flaw. The mitigation strategy involves updating to the patched version of Octopus Deploy and implementing additional security controls such as network segmentation and privilege monitoring to limit potential damage. Security teams should also review and audit existing deployment process configurations to identify any potentially malicious or unauthorized modifications. Access controls should be strictly enforced, ensuring that only authorized personnel have permissions to modify deployment processes, and that these permissions are regularly reviewed and audited. The vulnerability highlights the importance of input validation and secure configuration management practices, aligning with NIST cybersecurity frameworks and the principle of defense in depth. Organizations should also consider implementing additional monitoring and logging of deployment process modifications to detect potential exploitation attempts and maintain compliance with security standards such as ISO 27001 and CIS Controls. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other deployment automation tools and systems within the organization's infrastructure.