CVE-2023-50263 in Nautobot
Summary
by MITRE • 12/13/2023
Nautobot is a Network Source of Truth and Network Automation Platform built as a web application atop the Django Python framework with a PostgreSQL or MySQL database. In Nautobot 1.x and 2.0.x prior to 1.6.7 and 2.0.6, the URLs `/files/get/?name=...` and `/files/download/?name=...` are used to provide admin access to files that have been uploaded as part of a run request for a Job that has FileVar inputs. Under normal operation these files are ephemeral and are deleted once the Job in question runs.
In the default implementation used in Nautobot, as provided by `django-db-file-storage`, these URLs do not by default require any user authentication to access; they should instead be restricted to only users who have permissions to view Nautobot's `FileProxy` model instances.
Note that no URL mechanism is provided for listing or traversal of the available file `name` values, so in practice an unauthenticated user would have to guess names to discover arbitrary files for download, but if a user knows the file name/path value, they can access it without authenticating, so we are considering this a vulnerability.
Fixes are included in Nautobot 1.6.7 and Nautobot 2.0.6. No known workarounds are available other than applying the patches included in those versions.
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Analysis
by VulDB Data Team • 01/04/2024
The vulnerability described in CVE-2023-50263 affects Nautobot versions 1.x and 2.0.x prior to 1.6.7 and 2.0.6 respectively, representing a critical authorization flaw within the web application's file handling mechanisms. This issue stems from improper access controls on specific endpoints that manage file retrieval for automated job processes, creating a pathway for unauthorized file access that could potentially expose sensitive data or system resources. The affected URLs `/files/get/?name=...` and `/files/download/?name=...` are designed to provide administrative access to temporary files uploaded as part of Job execution processes that utilize FileVar inputs, which are typically ephemeral and automatically deleted after job completion. The vulnerability manifests due to the default implementation of file storage through `django-db-file-storage` which fails to enforce user authentication requirements for these specific endpoints, despite their intended purpose of accessing restricted administrative files.
The technical nature of this vulnerability aligns with CWE-285, which addresses improper authorization in software systems, specifically manifesting as an authorization bypass that allows unauthenticated access to protected resources. The flaw exists because the application's access control mechanisms are not properly implemented on the file retrieval endpoints, creating a scenario where any user can access files if they know the specific file name, even though the system does not provide a mechanism for directory traversal or enumeration of available files. This represents a classic case of insufficient authorization checks where the application assumes that the mere presence of a file name parameter is sufficient for access, without verifying user credentials or permissions. The vulnerability is particularly concerning because it operates on the principle of "security through obscurity" being insufficient, as the lack of proper authentication mechanisms means that even if file names are not directly discoverable through enumeration, they can still be accessed through guesswork or other means of information gathering.
From an operational impact perspective, this vulnerability could enable attackers to access sensitive data that was intended to be restricted to authorized administrative users only, potentially including configuration files, logs, or other potentially sensitive information that might have been uploaded as part of automated job processes. The exposure of such files could lead to information disclosure, system compromise, or other security incidents depending on the nature of the data contained within the accessible files. Attackers could leverage this vulnerability to gain unauthorized access to job-related artifacts that might contain credentials, system configurations, or other sensitive information that could be used for further attacks within the network infrastructure managed by Nautobot. The impact is amplified by the fact that these files are part of automated job processes that might be executed with elevated privileges or contain information relevant to network operations and security posture.
The mitigation for this vulnerability requires immediate upgrade to Nautobot versions 1.6.7 or 2.0.6, which contain the necessary patches to implement proper authentication requirements for the affected file retrieval endpoints. These updates ensure that users must possess appropriate permissions to access FileProxy model instances before being granted access to the files, thereby implementing proper authorization controls as required by security best practices. Organizations should also consider implementing additional monitoring and access controls around file storage areas to detect any unauthorized access attempts or unusual file access patterns. The fix addresses the core issue by enforcing proper access control checks on the file retrieval endpoints, ensuring that only users with appropriate permissions can access files through the `/files/get/` and `/files/download/` URLs, thus preventing unauthorized access to potentially sensitive data that is part of the automated job execution processes within the Nautobot platform. This vulnerability demonstrates the importance of implementing proper authentication and authorization controls even for seemingly simple file access mechanisms, as the absence of such controls can lead to significant security risks within network automation platforms.