CVE-2022-30136

What it actually does

CVE-2022-30136 is a remote code execution vulnerability in the Windows Network File System (NFS) service. A network-adjacent or remote unauthenticated attacker can send specially crafted NFS traffic to an affected Windows Server running the NFS role and cause code execution on the target system. Because the CVSS vector is AV:N/AC:L/PR:N/UI:N with high confidentiality, integrity, and availability impact, exploitation does not require credentials or user interaction and may allow the attacker to execute arbitrary code in the context of the vulnerable service, potentially leading to full server compromise.

Why it matters to the business

Organizations running the Windows Server NFS role on affected versions face a high-impact server compromise risk. Successful exploitation could allow attackers to take control of file-serving infrastructure, steal or modify shared data, disrupt application workloads that depend on NFS shares, deploy malware, or use the compromised server as a pivot point into the broader network. Although this vulnerability is not listed in CISA KEV and no ransomware use is indicated in the provided data, the high CVSS score and high EPSS probability mean exposed NFS services should be treated as urgent remediation priorities, especially where NFS is reachable from untrusted networks.

How an attack unfolds

An attacker first identifies Windows Server systems exposing the NFS service, typically by scanning for NFS-related ports and confirming that the target is running Microsoft’s NFS implementation on an affected Windows Server version. The attacker then sends crafted NFS protocol requests designed to trigger the vulnerable code path in the Windows NFS service. If exploitation succeeds, the service processes the malicious request in a way that results in attacker-controlled code execution. From there, the attacker may establish persistence, run commands, access or alter files available to the server, dump credentials or tokens available on the host, disable defenses, and move laterally to other systems that trust or depend on the compromised server.

How to fix it

Apply the Microsoft security updates that address CVE-2022-30136 for all affected Windows Server systems, including Windows Server 2012, Windows Server 2016, and Windows Server 2019. Because no fixed version list was provided, use the applicable Microsoft June 2022 or later cumulative/security updates for the exact operating system build and servicing channel. Prioritize systems running the NFS role, especially those reachable from untrusted networks. If immediate patching is not possible, reduce exposure by disabling the NFS role where it is not required, restricting NFS access to trusted hosts only, blocking inbound NFS/RPC traffic at firewalls, segmenting file servers from general user networks, and monitoring NFS activity closely until updates are applied.

How to confirm the fix worked

Confirm whether the Windows NFS role is installed and running on affected servers, then verify that the applicable Microsoft security update for CVE-2022-30136 or a later cumulative update is installed. Administrators can validate exposure by checking installed Windows updates, OS build levels, and whether NFS services are listening on the network. Confirm that TCP/UDP 2049 and related RPC/NFS ports are not reachable from untrusted networks unless explicitly required. After remediation, perform authenticated vulnerability scanning or configuration assessment to confirm the system is no longer reported as vulnerable and verify that NFS service restrictions or firewall controls are operating as intended.

Typical attack path

1. Scan networks for systems exposing NFS services, commonly TCP/UDP 2049 and related RPC/NFS service ports.
2. Fingerprint the host as a Windows Server running the NFS role on an affected version such as Windows Server 2012, 2016, or 2019.
3. Send specially crafted NFS requests to trigger the remote code execution flaw.
4. Execute attacker-controlled code in the context of the vulnerable NFS service if exploitation succeeds.
5. Deploy a payload such as a reverse shell, command runner, credential theft tool, or malware loader.
6. Access, modify, or destroy data available to the server and its mounted or shared file paths.
7. Use the compromised server as a foothold for privilege escalation, lateral movement, data theft, or service disruption.

How to detect it

To determine whether exploitation may already have occurred, review network telemetry for unusual or untrusted NFS traffic to Windows servers, especially inbound connections to TCP/UDP 2049 and RPC-related ports from systems that are not legitimate NFS clients. Examine Windows event logs around suspicious NFS activity for service crashes, unexpected restarts, application errors, or faulting service processes associated with Microsoft NFS components. Hunt for post-exploitation artifacts on NFS servers: unusual child processes spawned by service-hosting processes, newly created local users, new services, scheduled tasks, suspicious PowerShell or command-shell execution, credential access tooling, unexpected outbound connections, and changes to files in shared directories. Correlate any anomalous NFS traffic with endpoint telemetry showing process execution, privilege escalation, or lateral movement. No specific public exploit strings or payload markers are inherent to this CVE from the provided data, so detection should focus on NFS exposure, malformed or anomalous NFS requests, service instability, and generic post-compromise behavior.

• tcp/2049
• udp/2049
• Service for NFS
• Server for NFS
• NfsService
• nfssvc.exe
• Event ID 7031
• Event ID 7034
• Event ID 1000
• cmd.exe /c
• powershell.exe -enc
• powershell.exe -EncodedCommand
• wscript.exe
• cscript.exe
• rundll32.exe
• regsvr32.exe
• schtasks /create
• sc.exe create
• net user
• net localgroup administrators

What your security team should do

• Inventory all Windows Server 2012, 2016, and 2019 systems and identify which have the Server for NFS role enabled.
• Patch all affected NFS-enabled Windows servers with the applicable Microsoft security update or later cumulative update as a high priority due to the 9.8 CVSS score and high EPSS probability.
• Immediately restrict network access to NFS services so only trusted clients can reach TCP/UDP 2049 and related RPC/NFS ports.
• Disable the NFS role on any server where it is not required.
• Review perimeter and internal firewall rules to ensure Windows NFS services are not exposed to the internet or broad internal networks.
• Run vulnerability scans after patching to verify CVE-2022-30136 is remediated.
• Hunt for suspicious NFS traffic, crashes of NFS-related services, unexpected child processes from service hosts, and post-exploitation activity on file servers.
• Increase monitoring of affected servers for credential dumping, new services, scheduled tasks, unusual administrative logons, and lateral movement attempts.