Urgent Security Alert: Critical Windows SMB Vulnerability (CVE-2022-26925) Under Active Attack
Cybersecurity authorities are issuing urgent warnings about a critical vulnerability in Microsoft Windows that is being actively exploited by malicious actors. This serious security flaw, tracked as CVE-2022-26925, can allow an attacker to gain complete control over an affected system, leading to a full network compromise.
This vulnerability is not theoretical; it is a clear and present danger to organizations of all sizes. Due to confirmed in-the-wild exploitation, immediate action is required to secure your network infrastructure.
Understanding the Threat: What is CVE-2022-26925?
The vulnerability resides within the Windows Server Message Block (SMB) protocol, a fundamental component used for file sharing, printer sharing, and other network communications. Specifically, the flaw allows for a sophisticated attack method known as an NTLM relay attack.
In this scenario, an unauthenticated attacker can coerce a domain controller to authenticate against a malicious server controlled by the attacker. This manipulation effectively “relays” the authentication credentials, tricking the system into granting the attacker elevated privileges.
The ultimate impact of a successful exploit is privilege escalation. A low-privilege user on the network can exploit this flaw to gain permissions equivalent to a domain administrator, giving them the “keys to the kingdom.” From there, an attacker can deploy ransomware, exfiltrate sensitive data, or move laterally across the entire network undetected.
Why This Is a Top-Priority Threat
What elevates this vulnerability from a routine issue to a critical alert is the confirmation of active exploitation by threat actors. Federal cybersecurity agencies have added CVE-2022-26925 to their Known Exploited Vulnerabilities (KEV) catalog, a list of security flaws that pose a significant risk to the federal enterprise and other organizations.
This means that attackers are not just testing this exploit; they are actively using it in real-world campaigns to compromise networks. The window of opportunity to defend against this threat is closing rapidly. All supported versions of Windows and Windows Server are potentially affected, making the attack surface incredibly wide.
Actionable Steps to Protect Your Network Immediately
Protecting your organization from this exploit requires a swift and decisive response. Waiting is not an option. Follow these essential steps to mitigate your risk.
Patch Immediately: The most critical step is to apply the security updates released by Microsoft in May 2022. These patches directly address the root cause of the vulnerability and are the most effective defense. Prioritize patching domain controllers and other critical servers first.
Review System Configurations: The original patch for this vulnerability required an additional registry key modification to be fully effective. Ensure that your post-patching process confirms that all necessary configurations detailed in Microsoft’s security guidance are correctly implemented.
Implement Network Hardening Mitigations: If immediate patching is not possible, or for an added layer of defense, consider these security measures:
- Enable SMB Signing: This security mechanism helps prevent relay attacks by requiring digital signatures on SMB packets, ensuring their integrity and authenticity.
- Disable NTLM Authentication: Where possible within your environment, disable NTLM and enforce the use of the more secure Kerberos authentication protocol.
- Block Outbound SMB Traffic: At your network perimeter firewall, block outbound traffic on TCP port 445. This can prevent internal systems from connecting to malicious external SMB servers.
In today’s threat landscape, proactive defense is the only viable strategy. The active exploitation of CVE-2022-26925 serves as a stark reminder that known vulnerabilities are prime targets for attackers. Take the necessary steps to patch and harden your systems today to prevent a potentially devastating security incident.
Source: https://go.theregister.com/feed/www.theregister.com/2025/10/21/cisa_windows_smb_bug/
