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IT

I’ve Been an IdIoT

From time to time we have to be the family’s IT support. It comes with the profession. Today I had work to do for Mum and Dad. The CCTV just wasn’t working. They were going on holiday, hadn’t checked the cameras in a while but they weren’t accessible from their phones. They really wanted them back before they went away.

The tell tale signs quickly came apparent after I logged in to the NVR (Network Video Recorder) which is a Dahua model. The camera list read “HACKED”, “CHANGE”, “FIRMWARE”. The issue with the device falling off the network turned out to be that a deliberately faulty IPv6 address had been set which also knocked out IPv4 communication.

Best I can tell they had fallen victim to an attack that appeared back in 2017. The default super user account for this NVR is ‘88888888’ and the default password is ‘888888’. Last time I’d checked out the CCTV I noticed this was in place and I really should have changed this. On Dahua NVRs this super user account should not be accessible from remote. The system should check if the access request had been made from local or remote and – in case of the latter – deny access accordingly. The flaw apparently is that this check isn’t properly done. The article linked also references a Facebook post which suggests that using Dahua’s DDNS also made it easy for the attackers to identify and target vulnerable devices. My parents were indeed using Dahua’s DDNS.

In other words the system was a sitting duck on the internet.

I can only assume someone out there has written a script to look for vulnerable Dahua devices exposed to the internet, log in via the admin account using default or easy to guess passwords and then apply setting changes to forcibly remove these devices off the internet. Malicious but also a public service. The device runs an embedded version of Linux and could have easily ended up part of a botnet if hacked firmware was uploaded.

To resolve the attack I reset the unit to factory defaults, uploaded new firmware to both NVR and cameras then set accounts with strong passwords using the XKCD method. I do not have a high trust of IoT devices but not being particularly happy about going up a ladder to replace the cameras this was the best I could do.

It should be noted that Dahua’s website is diabolical for finding firmware updates. You cannot just search a model number to find the device and associated firmware. I needed to check a load of firmware releases to see which ones were pertinent. I had a few attempts with what I thought was correct firmware but apparently wasn’t. I am thankful that the devices can do checks of the firmware to be installed because the risk of bricking the devices in this scenario is real.

In the industry we all know the lessons and we all recognise when a chain of events start happening and not get stopped then the results can be catastrophic. In the case of my parents I assume someone’s shut off network access deliberately but the reality is that someone could’ve used the CCTV access to determine that nobody was in the house. The cameras point to the drive where their cars are parked after all.

Let’s conclude it by reiterating the standard points:

  • Default passwords (and arguably account names) aren’t acceptable for an internet facing device. I had an opportunity to change it and I didn’t. Whilst the admin account should not have been accessible remotely it was thanks to a firmware flaw. Changing that password could’ve stopped this attack in progress.
  • Firmware updates need to be done as often as they become available. Security issues happen. Pobody’s nerfect right? As soon as those vulnerabilities and fixes become apparent they need to be tested and deployed.
  • Trust is a weakness and no trust is owed to the average IoT device. The industry is notorious for bad security practices and abandoning devices within a short lifecycle. Ideally these devices shouldn’t be left open on the internet but placed behind a VPN where the access can be defended slightly better. That’s not a practical solution for most home networks so there must be an accepted risk.
  • I will reserve judgement on using a DDNS. The CCTV was registered with a *.dahuaddns.com address which I suppose makes it pretty easy to focus an attack if you can narrow it down to specific devices or a single manufacturer. I would suggest using a static IP instead but my parent’s ISP does not offer this. Comment below if you have anything to offer on this as I don’t know how much safer you are with a custom DNS.

By Joe Scott

A technical consultant from West Yorkshire, UK specialising in SQL Server. Member of Round Table Britain and Ireland. Challenging myself to open water swimming.

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