Advisory Details

This vulnerability allows remote attackers to execute arbitrary code on affected installations of Wecon LeviStudioU. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.

The specific flaw exists within the handling of XML files. When parsing the szFilename attribute of the MulStatus element, the process does not properly validate the length of user-supplied data prior to copying it to a fixed-length stack-based buffer. An attacker can leverage this vulnerability to execute code in the context of an administrator.

This vulnerability is being disclosed publicly without a patch in accordance with the ZDI 120 day deadline.

09/26/19 – ZDI provided the vulnerability reports to ICS-CERT
09/26/19 – ICS-CERT acknowledged the reports and provided an ICS-VU#
01/24/20 – ZDI requested any available update about the reports
01/24/20 – ICS-CERT indicated the vendor had acknowledged the reports, but that no further update was available
02/05/20 - ZDI requested any available update about the reports
02/06/20 – ICS-CERT replied that there was no update available
02/10/20 – ZDI notified ICS-CERT of the intent to publish the reports as 0-day on 02/20/20

-- Mitigation:
Given the nature of the vulnerability, the only salient mitigation strategy is to restrict interaction with the service to trusted machines. Only the clients and servers that have a legitimate procedural relationship with the service should be permitted to communicate with it. This could be accomplished in a number of ways, most notably with firewall rules/whitelisting.

• 2019-09-26 - Vulnerability reported to vendor
• 2020-02-20 - Coordinated public release of advisory