I've been deploying and evaluating Secureframe for our PCI DSS and SOC 2 Type 2 compliance program over the last quarter. The automated evidence collection is generally sound, but we've hit a persistent and critical blocker with the SCAP-based compliance scans for our Windows Server fleet (2019 & 2022). The scans consistently fail, and after a week of packet captures and log analysis, I've isolated the root cause to Windows Firewall rules—specifically, the default behavior when the scanner's source IP isn't whitelisted.
The Secureframe agent initiates a SCAP scan via the OpenSCAP library, which attempts to connect to the Windows target using Windows Remote Management (WinRM) and the Windows Management Instrumentation (WMI) stack. The failure pattern isn't a simple timeout; it's a structured rejection by the host's local firewall. Crucially, this occurs even on hosts where WinRM is explicitly enabled and listening.
Here’s the technical breakdown from our diagnostics:
* **Primary Issue:** The Windows Firewall `Windows Remote Management (HTTP-In)` rule is scope-limited. By default, it often restricts allowed source IPs to the local subnet. The Secureframe scanner, originating from its cloud infrastructure, does not match this scope.
* **Secondary Issue:** The SCAP checks require DCOM (WMI over RPC) access on dynamic high ports (TCP 49152-65535). The default `Windows Management Instrumentation (WMI-In)` rule allows this, but again, only for sources within the "Local subnet" scope.
* **Evidence from `Test-WSMan`:** Running a simple connectivity test from a permitted host works, but from the scanner's network perspective, it fails at the firewall layer. Packet captures show TCP SYN packets being dropped with no RST.
**Current Workaround & The Core Problem:**
Our temporary fix involves modifying the firewall rules via GPO or script to allow the Secureframe scanner CIDR ranges. This is operationally burdensome and a security concern.
```powershell
# Example of the rule modification we had to implement (via script/GPO):
Set-NetFirewallRule -Name "WINRM-HTTP-In-TCP" -RemoteAddress @("192.0.2.0/24", "ScannerCIDR2") -Direction Inbound
```
The core problem is that Secureframe's documentation on SCAP scanning is woefully inadequate for real-world enterprise environments. It assumes an open network path or provides only generic "enable WinRM" instructions. There is no official, maintained list of scanner IP ranges, nor guidance on firewall rule configuration for locked-down hosts.
**My questions for the community and Secureframe team:**
1. Does Secureframe maintain and publish a definitive, stable CIDR block list for its SCAP scanning infrastructure to allow for precise firewall whitelisting?
2. Has anyone engineered a more elegant solution than blanket firewall rule modifications? (e.g., a lightweight agent-based collector that pushes data instead of requiring cloud-pulled scans).
3. Is there a documented, approved method to provide equivalent compliance evidence for these Windows benchmarks without relying on the failing remote SCAP scan?
I'll be escalating this through our account channel, but I'm keen to hear if others have deconstructed this particular failure mode. The lack of network-level requirements documentation is a significant oversight for a product in this space.
-- alex
Default WinRM firewall rules are scoped to the local subnet for a reason. Opening them to a SaaS scanner's entire egress IP range is excessive.
Use a jump host or a dedicated scanner instance in the same VPC/VNet. Lock the rule to that single, internal IP. You shouldn't be allowing inbound WinRM from the internet, even from a vendor's IP space.
The real issue is the scanner design expecting this. Push back on Secureframe. Their agent should deploy a lightweight collector inside your perimeter, not probe WinRM from the outside.
Least privilege is not a suggestion.
Agreed, locking the rule to a single internal IP is the right move. The jump host idea is solid, but in practice we've found you often need to allow the vendor's IP range initially just to get their agent deployed onto that jump host in the first place, which creates a chicken-and-egg problem.
Instead, we used a temporary, highly restricted Network Security Group rule in Azure that only allowed WinRM from Secureframe's published IPs. Once their agent was installed on our internal scanner VM, we flipped the rule to only allow traffic from that VM to the target servers and dropped the external IPs entirely. It's an extra step, but it closes the perimeter again.
Automate everything. Twice.