CVE-2018-0824: Microsoft COM for Windows Deserialization of Untrusted Data Vulnerability

CVE-2018-0824 is a deserialization of untrusted data vulnerability in Microsoft COM for Windows. Per the CISA summary, it allows privilege escalation and remote code execution via a specially crafted file or script.

COM is a foundational Windows component, so this class of flaw can put systems at risk of full compromise if untrusted input reaches the vulnerable path. Confirm exact impact, affected configurations, and fixes against the vendor advisory.

How it works

The weakness is CWE-502: Deserialization of Untrusted Data. In this class of flaw, software accepts serialized objects or data streams from an untrusted source and reconstructs them without adequate validation or type restrictions. An attacker who can supply the data can embed objects that, when deserialized, trigger unintended method calls, object construction, or code execution in the context of the process performing the deserialization.

For this Microsoft COM vulnerability, the CISA summary states that a specially crafted file or script is used to reach the vulnerable deserialization logic, resulting in privilege escalation and remote code execution. No further exploit mechanics are provided here; defenders should treat any untrusted file or script interaction with COM as a potential vector and obtain precise details from the vendor advisory.

Am I affected? How to find it in your systems

The vulnerability affects Microsoft Windows systems that use COM. COM is present by default on most Windows installations and is commonly invoked by applications, scripts, services, and administrative tools.

• Inventory all Windows hosts (workstations, servers, domain controllers, and virtual machines) and map which ones run software or scripts that create or consume COM objects.
• Compare installed Windows builds and update levels against the versions listed in the Microsoft advisory for CVE-2018-0824; do not assume any particular release is safe without confirmation.
• Identify processes and services that load COM-related libraries or that accept files/scripts from untrusted sources (user shares, email, web downloads, remote administration tools).
• Review logs for anomalous process creation, unexpected elevation of privilege, or script/file execution that coincides with COM activity. Telemetry from endpoint detection tools that monitor object deserialization or unusual COM activation can surface suspicious behavior, though exact indicators must be validated against vendor guidance.

How to remediate

Patch first. Apply the vendor-supplied update for CVE-2018-0824 as described in the Microsoft advisory. CISA’s required action is to apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

• Deploy the update through your standard patch management process, prioritizing internet-facing, high-privilege, and multi-user systems.
• Verify successful installation by checking the update history or build information against the advisory.
• After patching, reduce residual risk for this weakness class by limiting the attack surface: restrict which accounts and processes can instantiate COM objects, enforce least privilege, and ensure that any remaining serialization paths reject untrusted input.

If you can't patch immediately

Use compensating controls to lower the likelihood and impact of exploitation until the vendor update can be applied.

• Network segmentation: isolate Windows hosts that process untrusted files or scripts from critical assets and limit lateral movement paths.
• Application control and script restrictions: block or tightly constrain execution of untrusted scripts and files that could interact with COM.
• Disable or restrict non-essential COM functionality and features that accept external input where operationally feasible.
• Virtual patching or host-based controls: if available, apply rules that inspect or block suspicious deserialization patterns or COM activation from untrusted sources.
• Heightened monitoring: alert on privilege-escalation events, unexpected COM object creation, and anomalous file/script activity; retain logs for forensic review.

If your data may have been exposed

Actively exploited vulnerabilities of this type can lead to system compromise and subsequent data exposure. Ransomware use is not documented for this CVE. If you suspect exploitation, isolate affected hosts, preserve forensic evidence, and follow your incident-response process. You can also run a free exposure scan of your email address to check whether it appears in known breach data sets.