CVE-2023-34994: TALOS-2023-1773 || Cisco Talos Intelligence Group

SUMMARY

An improper resource allocation vulnerability exists in the OAS Engine configuration management functionality of Open Automation Software OAS Platform v18.00.0072. A specially crafted series of network requests can lead to creation of an arbitrary directory. An attacker can send a sequence of requests to trigger this vulnerability.

CONFIRMED VULNERABLE VERSIONS

The versions below were either tested or verified to be vulnerable by Talos or confirmed to be vulnerable by the vendor.

Open Automation Software OAS Platform v18.00.0072

PRODUCT URLS

OAS Platform - https://openautomationsoftware.com/knowledge-base/getting-started-with-oas/

CVSSv3 SCORE

3.1 - CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L

CWE

CWE-770 - Allocation of Resources Without Limits or Throttling

DETAILS

The OAS Platform, capable of running on a variety of systems including Windows, Linux, and Docker, was built to facilitate simplified communication between various proprietary devices and applications that might otherwise be incompatible. This is done through use of the “Universal Data Connector”. In the “Connectivity Layer” OAS acts as an “IoT Gateway and protocol bus,” allowing for native communication with devices, databases, and cloud services. Connectors implemented in the “Connectivity Layer” can then communicate with each other via the OAS Live Data Cloud, representing the “Aggregation Layer”. This information can then be stored, analyzed, and visualized through the data historian, alarm logging/notification, and visualization tools that make up the “Application Layer”. OAS additionally exposes a few sets of developer tools, allowing for programmatic access to the platform.

Through the OAS Configuration tool, the functionality to load a saved configuration from disk or save a running configuration to disk is exposed to authenticated application users. Accompanying the configuration management tools is a remote file browser that allows users to create new directories.

It is important to note that these users exist within the OAS Engine exclusively, not on the underlying system. This means that an application user who is not authorized on the underlying system is capable of creating new directories anywhere that the underlying OAS user system account has access.

To create a new directory, a Create_Directory protobuf can be leveraged as part of a greater authenticated request. The format of this structure resembles the following, where the ExistingDirectory field contains the full path to the location where the new directory should be created, and the NewDirectory field contains the name of the new directory:

message Create_Directory {
  int32 Version = 1;
  U_EP UEP = 2;
  string ExistingDirectory = 3;
  string NewDirectory = 4;
}

Mitigation

Access to the OAS Engine configuration server and its traffic should be restricted to exclusively those hosts authorized for configuration. Additionally, where possible restrict read/write access for the OAS user to only locations that can safely be exposed to anyone on the network.

VENDOR RESPONSE

The fixed version v19 can be downloaded from: https://openautomationsoftware.com/downloads/releases/

TIMELINE

2023-06-22 - Vendor Disclosure
2023-09-02 - Vendor Patch Release
2023-09-05 - Public Release

Discovered by a member of Cisco Talos.