Credssp Remote Code Execution Vulnerability March 2018 Security Update: Patch Verification Steps for Windows Systems

Microsoft’s CredSSP remote code execution vulnerability March 2018 security update was critical, leaving Windows systems dangerously exposed as attackers exploited remote sessions.

Picture this: A single unpatched machine on your network becomes the perfect entry point for a wormable exploit, spreading like wildfire across your entire system. Microsoft’s KB4093112 update fixed the flaw, but many still don’t know if their systems are truly protected.

This vulnerability, tracked as CVE-2018-0886, affected Windows 7 through Server 2016, enabling privilege escalation and full system compromise. The stakes? Data breaches, ransomware, and complete network domination—all because one update was missed.

In this guide, I’ll walk you through how to verify your patch status, spot hidden risks, and lock down CredSSP for good—so you can sleep easy knowing your defenses are airtight.

How to identify the CredSSP vulnerability patch in Windows systems

The CredSSP Remote Code Execution Vulnerability (CVE-2018-0886) was a critical flaw in Windows’ Credential Security Support Provider protocol. Microsoft released KB4093112 in March 2018 to fix it, but many systems still lack the patch. Here’s how to verify your Windows 7/8.1/10 or Server 2012/2016 is protected.

This vulnerability allowed attackers to execute malicious code remotely by exploiting Remote Desktop Services. Without the patch, systems were exposed to privilege escalation and even wormable exploits. Let’s confirm your system has the security update installed.

If you’re using Windows Server 2012/2016, also check the Security Update Installation log in C:\Windows\Logs\CBS\CBS.log for entries related to KB4093112. This log contains detailed installation timestamps and statuses.

For Remote Desktop Services (RDS) environments, ensure all session hosts and connection brokers are patched. Unpatched servers can still be exploited even if clients are updated.

If the patch is missing, manually install it from Microsoft’s Update Catalog using the KB4093112 link. After installation, reboot your system to apply changes.

Pro tip: Use Windows Server Update Services (WSUS) or Microsoft Endpoint Configuration Manager to automate patch verification across multiple machines in enterprise environments.

Remember, this patch isn’t just about CredSSP—it also includes fixes for CVE-2018-0887, another critical remote code execution flaw in the same protocol.

Common mistakes that leave systems vulnerable after patching

Applying the March 2018 CredSSP patch (KB4093112) is just the first step—many systems remain exposed due to misconfigurations. I’ve seen environments where admins installed the patch but overlooked critical settings like Group Policy or Remote Desktop Services updates.

These oversights can leave systems just as vulnerable as if no patch were applied at all.

One frequent issue is assuming the patch alone secures Remote Desktop Protocol (RDP) connections. The CredSSP vulnerability thrives on unencrypted RDP sessions, so even patched systems can be exploited if Network Level Authentication (NLA) isn’t enforced. Without NLA, attackers bypass the patch entirely by exploiting the underlying protocol.

Another common mistake is ignoring cumulative updates after the initial patch. Microsoft often releases follow-up fixes for CredSSP-related issues in later updates. For example, Windows 10 version 1803 introduced additional hardening for CredSSP, but many users stopped patching after the March 2018 update, leaving them exposed to newer variants.

Some organizations also neglect to verify whether third-party tools relying on CredSSP (like older versions of VMware Horizon or Citrix Virtual Apps) are compatible with the patch.

If these tools don’t support the updated CredSSP encryption protocols, they can force systems back into an insecure state by downgrading security settings.

To avoid these pitfalls, I recommend running a PowerShell audit of CredSSP settings across your estate. Check for the presence of KB4093112 and the correct Registry keys (e.g., EncryptionOracleRemediation). For RDP-heavy environments, enforce NLA and disable CredSSP entirely if not needed—this is the most secure option for non-RDP workloads.

Finally, don’t assume older Windows versions (like Windows 7 or Server 2012) are safe just because they received the patch. These systems often lack the TLS 1.2 support needed for modern CredSSP encryption. Upgrade or isolate them immediately to prevent exploitation.

Advanced verification: using PowerShell to audit CredSSP security settings

As an IT admin, verifying CredSSP encryption settings across multiple machines is critical to mitigate the March 2018 vulnerability (CVE-2018-0886). Microsoft introduced two key registry settings to enforce secure connections: RequireEncryptionForAuth and EncryptionOracleRemediation. These settings must be properly configured to prevent unencrypted authentication and oracle attacks.

PowerShell provides an efficient way to audit these settings remotely. You can use the Get-ItemProperty cmdlet to check registry values on local or remote systems. For large environments, combine this with a foreach loop to scan multiple machines.

This ensures consistency and reduces manual errors, which are common when verifying security settings across hundreds of endpoints.

To automate this process, use the following PowerShell script. It connects to remote machines and checks if the required registry values are set correctly. For example, this script can be run against a list of servers stored in a CSV file or pulled from Active Directory.

Always test it in a non-production environment first to ensure compatibility with your Windows versions (e.g., Server 2012 R2, Server 2016, or Windows 10/11).

For systems where these settings are missing or misconfigured, deploy a Group Policy or use PowerShell remoting to enforce the correct values. Regular audits—especially after major updates—help maintain a secure CredSSP posture and reduce exposure to remote code execution risks. 🖥️

Frequently asked questions about the CredSSP security update