UniFi OS Hacking

With the UDM / UDM Pro I’ve been regularly expressing disappointment that Ubiquiti is transitioning to a custom Linux distro that doesn’t have a package manager and doesn’t really have any provisions for persisting anything useful across reboots — particularly configuration changes and mechanisms to launch your own scripts.

With the second-stage transition to “UniFi OS” they’ve been moving more things into containers and it has now spread from the UDM Pro to the UNVR-4, which was previously running straight Debian with no containers.

Yesterday it was pointed out to me that “UniFi OS” isn’t merely a re-branding of the “UbiOS” the UDM debuted with. The unfi-os container is a full Debian environment. A quick investigation on my UDM Pro showed that I could enter the unifi-os container, apt install software packages, and make changes which persist across reboots. It would appear that all changes within the container are persistent via an overlay for / which goes to persistent storage on the host.

This is not at all how Containers are supposed to be used, it is a gross violation of best practices… but it’s a foot in the door to using these devices in ways that Ubiquiti didn’t bless.

I’m super-disappointed that nobody seems to be exploring the unifi-os container in public. Google turns up nothing, there hasn’t been anything meaningful on /r/UniFi or ubntwiki.com. Probably all hidden on the Discord.

I don’t love UniFi Threat Management and neither should you

When Ubiquiti put out the first Beta releases of IDS / IPS, I was surprised by the overall excitement of the enthusiast community. People were snatching up $2,000+ USG-XG-8s just to be able to use this feature without slowing down their WAN. Cheaper line-rate IDS / IPS has been a major force behind the UDM / UDM Pro hype train.

I am far less enthused, about IDS / IPS specifically and UniFi Threat Management in general.

My core issue: It’s Free.

Free is not inherently bad. I use lots of things that are free. Ubiquiti is built on lots of things that are free — VyOS, Linux, OpenWRT, hostapd. But security is different. Security is a process, not a deliverable.

Look at how Ubiquiti is offering security. Did they produce an IDS / IPS product? No, it’s just Suricata. Are they employing an army of security professionals to discover new threats, analyze alerts from their customers, produce new signatures? No, they’re just passing along the free rulesets that any Suricata user has the ability to use. Is Ubiquiti adding any value to Suricata alerts, such as making them easier to interpret or correlate? Heck no.

There’s a saying that If you’re not the customer, you’re the product. Does that apply here? Also, no. Enabling UniFi’s IDS/IPS isn’t passing any value back to the Open Information Security Foundation, the Suricata project, or any of their sponsoring organizations.

My other issue: What Ubiquiti is providing isn’t particularly good.

IDS / IPS: Suricata is purely signature based, like an antivirus program from 30 years ago… only worse. Most signatures are simplistic, prone to false positives, and the alerts they generate do not provide much context to decide whether they warrant further investigation or can be ignored. I’m not positive about this, due to the minimal information provided, but I think many of the alerts I’ve received are for traffic that the firewall was going to drop anyways.

There are many things Ubiquiti could be doing to add value to Suricata alerts — pruning rulesets and providing more context would be a great start — but that would require substantial investment.

Zeek (Bro) is generally considered better than Suricata, in that it’s focussed on flagging anomalous traffic instead of depending on signatures, but turning that into a user-friendly solution also requires significant investment.

DNS Filtering: I’ve previously written about this. In short, they’ve delivered an extremely simplistic filtering solution that depends on redirecting DNS traffic to an undisclosed 3rd-party. The manner in which they’ve implement filtering is unsuitable for a broad range of common DNS scenarios and they’ve provided zero control beyond choosing from the 3rd-party’s three filtering options.

It’s not worth using. Use PiHole and / or OpenDNS at home. Subscribe to Cisco Umbrella for business filtering.

Network Scanners: The Endpoint Scanner is basically a point-in-time nmap. No history, no correlation with UniFi’s Client History data. The Internal Honeypot is also extremely simplistic — it seems to alert simply on connection attempts to particular ports.

GeoIP Filtering: Hey, it does exactly what’s expected! I wish it did more tho. In particular, I might like to drop traffic from some countries to particular ports (VPN-related) but not others (HTTP / HTTPS).

IP Reputation: Tor blocking and Restrict Access to Malicious IP Addresses do what they say, tho again, it’s unclear what the information source is and if 3rd-party disclosures are involved.

Missing Features: Competing Unified Threat Management solutions generally have features that Ubiquiti isn’t (yet) providing: A/V scanning, HTTP / HTTPS interception, email filtering, data loss (PII / PHI exfiltration) protection, integration with Network Access Protection / Network Access Control systems, and more.


 

At some level it’s great that Ubiquiti is making security tooling available to users with less technical expertise or budget. What’s not great is those are the demographics who will read the marketing and believe they’re getting much more than is actually being provided.

The Real MGP

UniFi Management Gateway Pro, that is. Who comes up with these names?

UMG-frontUMG-back

Freshly announced, ahead of being available for Early Access purchase, we have essentially a UDM Pro… minus the switch, minus the HDD bay, half the RAM… and no local controllers! Adopt it to your Cloud Key, cloud-provider, or self-hosted UniFi install.

It also has a built-in UniFi Smart Power Plug. I can understand why — reboot your Cable / DSL “modem” if the Internet goes down — but it’s just such an odd thing to integrate into what is otherwise a plain router.

I’m happy to see this, tho disappointed that it’s not in more of an ER-4 form-factor with an optional rack mount kit. Hopefully this is a sign that a smaller-but-equally-capable desktop unit will come eventually.

I’m also hoping that this is a sign that in the future it will be possible to disable all local controllers on the UDM / UDM Pro.

Update: They’ve tweaked the original post, now it’s “UniFi Managed Gateway Pro” and the UMG Pro will be the first of the “UniFi Managed Gateway Product Line.”

UniFi Internet Security DNS Filtering

Today I was prompted to figure out what exactly the DNS Filters settings in UniFi Internet Security are doing.

unifi-dns-filtering

The main thing that happens is that the DNS queries for the associated VLAN are forwarded to the cleanbrowsing.org public resolver for the chosen filtering category. This is accomplished by creating a new dnsfilter network interface, binding another instance of dnsmasq to it, and using NAT to redirect DNS queries from the associated VLAN.

The implementation is slick from a technical perspective but I have a couple major problems with it.

Firstly, cleanbrowsing.org supports DNS-over-TLS, DNS-over-HTTPS, and DNSCrypt, but Ubiquiti has chosen to forward the queries unencrypted.

Secondly, if you’re using a local DNS server, say Active Directory or PiHole, those NAT rules will prevent the local DNS from functioning when queries are coming from or destined to a filtered VLAN. This might be fixable with some config.gateway.json or scripting hackery on the USG, I have not dug into that, but UDM users are hosed since there is no json replacement nor a way to automatically run a script.

Thirdly, Ubiquiti could have licensed the cleanbrowsing.org RPZs, converted them to dnsmasq format for local blacklisting ala PiHole, and eliminated the need to forward DNS to a 3rd-party and interfere with cross-VLAN DNS.

I cannot recommend using this DNS filtering because it will cause issues if your DNS implementation isn’t “UniFi Default” and the filtering options are minimal. My personal preference for home use is a PiHole in conjunction with OpenDNS Home.

For an office, Cisco Umbrella is the way to go. Do not underestimate the value of having a commercial relationship with a security provider. I <3 PiHole, but if you try to figure out why it blocks, say, zombo.com, and how you’d get it removed, you will immediately recognize that “free” security lists aren’t worth more than you’re paying for it.

Update: Also want to point out that the dnsfilter interfaces use IPs in the 203.0.113.0/24 subnet. That is TESTNET-3 in RFC 5737. It’s unlikely this will ever cause a problem… but over the long haul, every misuse of an IPv4 subnet ends up causing a problem. The loopback range 127.0.0.0/8 or link-local 169.254.0.0/16 would have been more appropriate choices.