IOServer released a new version of its OPC Server application that partially mitigates the vulnerabilities found in the software.
Independent researcher Hinge of foofus.net, who found the vulnerability, tested the new version and found that it partially resolves these remotely exploitable vulnerabilities, according to a report on ICS-CERT. Exploits that target these vulnerabilities are publicly available.
IOServer OPC Server 188.8.131.52 and earlier are the versions affected by the issue.
These vulnerabilities allow an attacker to download any file on the file system without authentication.
IOServer is an Australia-based company that produces the OPC Server, designed to exchange data between the human-machine interface and the programmable logic controllers. IOServer said its OPC Server deploy across several sectors including manufacturing, building automation, oil and gas, and electric utilities. IOServer said these products are primarily in the United States and Europe with a small percentage in Asia.
CVE-2012-4680 is the number assigned to these three closely related vulnerabilities, which has a CVSS v2 base score of 7.8.
The three vulnerabilities are insufficient access controls, directory listing, and directory transversal.
The application stores sensitive data under the Web document root with insufficient access control, which might make it accessible to unauthorized parties.
In addition, the product stores sensitive information in files or directories accessible to actors outside of the intended control sphere.
The software uses external input to construct a pathname that is intended to identify a file or directory located underneath a restricted parent directory. However, the software does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. This allows arbitrary access to any file on the server.
IOServer did create a new version (Version 184.108.40.206) to correct the directory traversal vulnerability. The researcher found this new version still contains insufficient access controls and allows directory listings inside the root directory and its subdirectories.
In addition to the patch, the researcher recommends users ensure the “Root Directory” configuration value has a trailing backslash. This helps to mitigate the remaining issues, although an attacker can still get a directory listing of the root directory itself (but not subdirectories) with this in place.