CVE-2018-12475 in Open Build Service
Summary
by MITRE
A Externally Controlled Reference to a Resource in Another Sphere vulnerability in obs-service-download_files of openSUSE Open Build Service allows authenticated users to generate HTTP request against internal networks and potentially downloading data that is exposed there. This issue affects: openSUSE Open Build Service .
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Analysis
by VulDB Data Team • 11/12/2020
The vulnerability identified as CVE-2018-12475 represents a critical security flaw within the openSUSE Open Build Service's obs-service-download_files component, classified under the CWE-202 category for externally controlled references to resources in other spheres. This issue manifests as an insecure direct object reference vulnerability that enables authenticated users to manipulate resource access patterns and potentially bypass intended security boundaries. The flaw specifically resides in how the build service handles external resource downloads, creating an attack vector where legitimate users can leverage their authenticated access to initiate HTTP requests against internal network resources that should otherwise remain protected from external access.
The technical implementation of this vulnerability stems from insufficient validation of resource references within the download service functionality. When authenticated users submit build requests that involve downloading files from external sources, the system fails to properly sanitize or validate the URLs provided by users. This allows attackers to craft malicious download requests that target internal network resources, potentially including sensitive systems, databases, or administrative interfaces that are not directly exposed to the public internet. The vulnerability essentially enables a form of internal network reconnaissance and data exfiltration through the legitimate build service infrastructure.
The operational impact of this vulnerability extends beyond simple data exposure, creating potential pathways for more sophisticated attacks within the build environment. An authenticated attacker could leverage this flaw to access internal systems that are typically protected by network segmentation, potentially gaining access to build artifacts, source code repositories, or even administrative interfaces of the build service itself. The attack surface is particularly concerning because it operates within the legitimate workflow of the build service, making detection more challenging and potentially allowing for prolonged unauthorized access without triggering standard security monitoring alerts. This vulnerability directly aligns with ATT&CK technique T1071.004 for application layer protocol usage and T1046 for network service discovery.
Mitigation strategies for CVE-2018-12475 should focus on implementing strict input validation and resource reference sanitization within the obs-service-download_files component. Organizations should enforce network segmentation policies that prevent the build service from accessing internal network resources, implement proxy configurations that restrict outbound connections to approved domains only, and establish comprehensive monitoring for unusual download patterns or requests targeting non-standard resources. Additionally, the service should be configured to operate with minimal necessary privileges and should validate all external resource references against a predefined whitelist of approved domains or IP ranges. The vulnerability underscores the importance of principle of least privilege and proper resource isolation in build and CI/CD environments, with remediation efforts aligning with security best practices outlined in NIST SP 800-53 and ISO 27001 frameworks. Regular security audits of build service components and automated vulnerability scanning should be implemented to prevent similar issues from emerging in future deployments.