How to filter out noisy internal scans from your threat feed without breaking rules?

You're right about the subnet list being a maintenance nightmare. The Log Source ID method everyone's circling is solid, but it hinges on one assumption: that your scanner's traffic is isolated.

If it isn't, you're back to square one. You'll spend that "one-time project" trying to get the logging team to split it out, and they'll just tell you it's not a priority. Seen it happen.

Might be easier to flag the scan sessions at the source. Make the scanner send a specific event your rules can key off of.

Yeah, the "tune your rules" advice always feels like it's missing the point. If it's not one rule, how do you even start?

The reference collection method everyone's talking about makes sense, but I'm new to this. When you tried the internal scanner subnet collection, was the main problem just keeping the IPs updated, or did it break other things too? Like, did excluding those subnets accidentally hide real traffic from somewhere else?

You're absolutely right that splitting the scanner traffic is a one-time project, but the key is treating that isolation as a formal logging requirement, not an ad-hoc request. I've seen teams get stuck because they approach the logging team with "we need to filter this noise," which gets deprioritized. Frame it as a security control: "Our vulnerability management platform requires a dedicated, immutable log source identifier for audit and compliance." That usually shifts it from a nice-to-have to a mandatory deliverable.

The other nuance is that once you have that dedicated log source, you should also hash its ID into your rule logic, not just the collection name. If someone renames or copies the reference collection, your rule breaks silently. The condition should be something like `AND NOT sourceLogSourceId=hash('sha256', 'Scanner_Controller_v1.0')`. This makes the dependency explicit and auditable.

That's a really good point about framing it as a compliance requirement. I hadn't thought of that. Makes total sense to get it prioritized.

The hashed ID trick is smart, too. It stops a simple rename from breaking everything. But if you go that route, how do you handle it when the scanner itself gets an upgrade and you need to change that ID? Do you just have to remember to update the hash in the rule logic manually?

Great question. That's exactly why the hashed ID should live in a reference collection, not hard-coded in the rule logic. You update the single source-of-truth collection when the scanner changes, and all the rules referencing it pick up the new hash automatically. The rule stays the same, it just queries the current value from the collection.

So your upgrade process is: update scanner, update the collection, test. No hunting through rule logic. It decouples the configuration from the detection logic, which is way more maintainable.

The catch is making sure that collection update is part of the official change control for the scanner upgrade. If that step gets missed, you're blind until someone notices.

Exactly! That decoupling is a huge win for maintenance. Been burned by that "missed step" scenario before, though.

We added a simple post-change validation check to our scanner upgrade runbook - a quick query that runs after the collection update to confirm the new ID is being excluded. It's a one-liner in our orchestration tool and catches the failure before the scanner even starts its first post-upgrade scan.

Might sound like overkill, but it's saved us from that exact blind spot at least twice when the change control checklist got... creative.

That automation step for validation is honestly brilliant. It turns a manual process into a self-healing one, and you're right, it's the exact kind of detail that gets skipped when a process gets "creative."

I'd add that making that query visible to a dashboard, not just part of a hidden orchestration script, can prevent the problem from even starting. When the logging team sees a big red "Scanner Isolation Failed" tile after an upgrade, they're motivated to fix it before you even file a ticket. It turns a technical check into a shared accountability metric.

Glad to hear it's saved you a couple of times, that's the best proof of concept there is.

Shared accountability only works if the teams share the same dashboard. If it's on your SOC dashboard but the logging team never sees it, it's just another alarm you have to chase.

That visibility has to be forced. We embedded that status check into the platform team's deployment health dashboard, the one they actually look at. No red tile on a dashboard they ignore.

Oh wow, this is exactly the kind of headache I'm trying to figure out at my place. The reference data collection for subnets seems like a good idea in theory, but reading this makes me realize how messy it gets fast.

You mentioned trying it across multiple business units. Did you have a central team managing that collection, or was each unit responsible for updating their own scanner IPs? I can imagine that coordination being its own full-time job, especially with dynamic IPs.

It sounds like the goal is a clean feed, but managing that exception list creates a whole new layer of work. Is the trade-off worth it, or is there a better starting point?

You're absolutely right about the cascading effect. Tuning individual rules is a losing battle because the scanner traffic influences building blocks like "Multiple Port Scan Sources" or "Reconnaissance Activity," which then feed into dozens of offense rules.

The most effective method I've found is to start from the root, at the log source level. Instead of filtering at the rule stage, you can create a dedicated, isolated log source for your vulnerability scanner's traffic. This involves working with the team that manages your log collectors or forwarders to have the scanner's traffic sent with a distinct, immutable identifier (like a specific source IP or a custom QID). You then create a Reference Data Collection that contains *only* that unique identifier.

You then modify the critical building blocks themselves. For example, in the "Reconnaissance Activity" building block, your condition becomes `AND [Log Source] NOT IN 'Scanner_Identifier_Collection'`. This excludes all scanner-sourced events from entering the logic chain at the very beginning, so they never propagate to any dependent rules. It centralizes the control point to a single reference collection update.

The maintenance burden shifts from managing a list of ephemeral IPs to managing a single, stable identifier. Even if the scanner's IP changes, the log forwarding rule can be configured to always apply that identifier, keeping the reference collection static. This approach does require initial coordination with the logging infrastructure team, but it's a one-time architectural fix versus endless rule tuning.