We're implementing DNS filtering with Pi-hole for all agent traffic, which is working well. Our current allowlist is locked down.
The problem is when a new agent version or feature needs to communicate with a new external domain for updates or telemetry. This seems to happen quarterly.
What's the operational best practice here? Letting the update fail and then manually adding the domain after a ticket feels reactive and creates a compliance gap (agents out of date). Pre-emptively allowing broad update domains seems to defeat the point.
Is there a common pattern for staging or canary-ing these new domain requests? Or a way to get ahead of the vendor's changes? We're particularly concerned about this under SOC 2 and HIPAA, as an update failure could lead to a vulnerability we can't patch.
Your core problem is letting the vendor drive your security boundary. They add a domain, you scramble to allow it.
You can't get ahead of their changes unless they publish a formal, versioned domain manifest with each release. Most don't, because they don't have to. Ask for it in your next contract review.
The compliance gap is real, but the alternative is whitelisting *.vendorcloud.com. That's worse. A failed update is a detectable event. A covert call-home channel you've pre-approved is a policy violation you'll never see.
Staging groups won't fix the fundamental issue. You're still reacting. Force the vendor to be predictable, or find one that is.
Show me the CVE.
You're right that predictability is the real fix. Getting a formal manifest in the contract is the goal, but I've found you can sometimes reverse-engineer a stopgap.
If the vendor provides a package (deb/rpm/docker) for their agent, you can extract the potential domains pre-deployment. Static analysis on the binaries or a quick run in a sandboxed network with a packet sniffer often reveals the endpoints it tries to hit. We do this now in a staging pipeline for any new agent version.
It's still reactive to their release cycle, but it moves the discovery from production failure to a pre-merge check.
trivy image --severity HIGH,CRITICAL
Static analysis and sandboxing is a solid tactical move, especially if you can bake it into your pipeline. I've done similar with `strace` and eBPF to catch DNS lookups.
The caveat is that some agents fetch configuration from an initial endpoint that then dictates subsequent domains. Your sandbox run might only see the first stage unless you simulate a full update cycle.
It's still a race, but you're right that shifting the failure to staging is an operational win. Have you hit any cases where the domains were obfuscated or only resolved via a CDN's anycast? That can make the allowlist a moving target.
Secrets? Not on my disk.
Yeah, that second-stage config fetch is a killer. Had one agent that pulled a JSON blob from a primary domain, which contained three new CDN hostnames for the actual update payload. Missed it in the initial sandbox run because the config was version-gated and our test environment didn't have an old enough agent version to trigger the update logic.
Obfuscation's rare in my experience, but CDN anycast is the norm now. You're not whitelisting a domain, you're whitelisting a provider. Makes the whole exercise feel a bit theatrical, honestly. You either trust Akamai or Fastly as a whole, or your update breaks.
Assume breach.
I'm still setting up my first agent, and this whole second-stage config fetch is worrying. If the sandbox only sees the first call, how do you trigger the full update cycle without pushing to prod? Do you just keep an old version running in staging forever?