CISA Alert: Water Sector PLC Targeting

Describe the network security of the industrial automation industry and their customers in a single statement. Lol.

I much prefer the non-vendor perspective on this. Andy Krapf, co-chair of the Water ISAC, has a great breakdown about the status quo systemic problems that water faces today.

The aim of a water network is to:

1. Take water from a water source (elevated dam -- strongly preferred, river, ocean) and as much as possible, gravity feed it to a treatment plant.

2. Treat the water using processes that are simplified/fail-safe as much as possible and could be operated manually by humans if necessary. This is where availability and safety engineers would design equipment to not be dependent on software and instead use mechanical or analogue electronics control.

3. Pre-position treated water as much as possible at ~50-90m hydraulic head (~500-900kPA) above the water faucets where people want to use the treated water and provide a buffer for X days of usage. Any pumps between the treatment plant and elevated storage therefore only need to operate intermittently to refill the buffer.

Sewerage networks have similar aims:

1. Let sewage flow as much as possible downhill to the treatment plant via gravity. Where a rising main (elevation gain) is required, place a large enough sump for X hours/days of usage and pump up to higher elevation from the sump.

2. Treat the sewage using processes that are simplified/fail-safe as much as possible and could be operated manually by humans if necessary. For example, a compressor used for aeration can be manually switched on/off with a mechanical switch and plugged into a diesel generator, and not require someone logging in with multi-factor authentication to a laptop to issue a command to a PLC to turn on the compressor.

3. Design overflows into the system for emergency release of partially or untreated sewage, and practice this process as part of disaster recovery exercises. This is generally an aim arising due to risk assessment process that says building a $1bn sump with 8 independent pumps is cost prohibitive versus the 1-in-200 year chance of untreated sewage messing up a downstream river for a few weeks.

Ultimately a lot of the cybersecurity risk comes down to government appetite to accept 1-in-1000 (or whatever) year failure modes. Is it worth investing now in triple modular redundant automated control systems (mostly used in safety-critical sectors such as aviation and space), or installing a just-in-case diesel generator at every one of 500 pumping stations across a region, or building $10bn of sewage sumps to hold sewage for up to a month, or building 2 treatment plants instead of 1 and using different technology for each, or hiring and training more humans to regularly exercise manual control and operation of a network, etc? Or just accept that once every 1000 years, some water rationing may be required, or a downstream river will be polluted for a few weeks?

CISA and its predecessors have been warning utility operators about critical infrastructure vulnerabilities for what, 15 years at this point? That goes back to the first Obama administration.

Yet here we are in 2026 and these utilities are still connecting these things to the raw Internet with default passwords. You cross a threshold where you're being deliberately careless.

When you are putting more effort into securing your Plex server on your home network then public utilities are taking on machinery that dumps chemicals into the local water, something is not right and finger-pointing isn't going to fix it.