CVE-2021-21243 in OneDev
Summary
by MITRE • 01/16/2021
OneDev is an all-in-one devops platform. In OneDev before version 4.0.3, a Kubernetes REST endpoint exposes two methods that deserialize untrusted data from the request body. These endpoints do not enforce any authentication or authorization checks. This issue may lead to pre-auth RCE. This issue was fixed in 4.0.3 by not using deserialization at KubernetesResource side.
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Analysis
by VulDB Data Team • 02/15/2021
The vulnerability CVE-2021-21243 affects OneDev, an all-in-one DevOps platform that provides integrated solutions for software development lifecycle management. This critical security flaw exists in versions prior to 4.0.3 and represents a severe pre-authentication remote code execution vulnerability that can be exploited without requiring any valid credentials or authentication. The vulnerability specifically targets the Kubernetes REST endpoint functionality within the platform, where two distinct methods are exposed to handle incoming requests. These methods perform deserialization operations on data received from the request body without proper validation or authentication checks, creating an exploitable attack surface that allows malicious actors to execute arbitrary code on the affected system.
The technical implementation of this vulnerability stems from the platform's failure to implement proper input validation and authentication mechanisms for the Kubernetes resource endpoints. When the KubernetesResource component processes incoming requests, it deserializes untrusted data directly from the request body without enforcing any authorization controls or authentication requirements. This deserialization process creates a dangerous attack vector because the platform accepts serialized objects from external sources without proper sanitization or verification. The vulnerability is classified under CWE-502 as "Deserialization of Untrusted Data" which is a well-known weakness that can lead to remote code execution when objects are instantiated from unverified serialized input. Attackers can craft malicious serialized payloads that, when processed by the vulnerable deserialization methods, execute arbitrary commands on the target system with the privileges of the OneDev service account.
The operational impact of this vulnerability is severe and far-reaching for organizations using affected versions of OneDev. Since the vulnerability allows pre-authentication remote code execution, attackers can exploit it from any network location without requiring valid credentials, making it particularly dangerous for systems accessible from the internet. The attack surface is expanded by the fact that the Kubernetes REST endpoints are exposed without authentication, meaning that any user with access to the platform's network can potentially exploit this vulnerability. This issue directly maps to ATT&CK technique T1059.007 "Command and Scripting Interpreter: PowerShell" and T1059.001 "Command and Scripting Interpreter: Command Shell" as attackers can leverage the RCE capability to execute malicious commands, establish persistence, and move laterally within the compromised environment. The vulnerability's exploitation can lead to complete system compromise, data exfiltration, and potential use as a foothold for further attacks within the organization's infrastructure.
The fix implemented in OneDev version 4.0.3 addresses the root cause by eliminating the deserialization functionality at the KubernetesResource side, which represents a defensive programming approach to prevent the exploitation of this vulnerability. This remediation aligns with security best practices outlined in the OWASP Top 10 2021, particularly the A08:2021 - Software and Data Integrity Failures category, which emphasizes the importance of preventing deserialization attacks. Organizations should prioritize upgrading to version 4.0.3 or later to mitigate this vulnerability, as the patch directly addresses the insecure deserialization pattern that was enabling the remote code execution capability. Additionally, administrators should consider implementing network segmentation, monitoring for suspicious API activity, and conducting thorough security assessments of their DevOps environments to ensure comprehensive protection against similar vulnerabilities that may exist in other components of their infrastructure. The vulnerability serves as a reminder of the critical importance of secure coding practices, particularly around deserialization operations, and the necessity of implementing proper authentication and authorization controls for all exposed endpoints in cloud-native and DevOps environments.