Steps To Take
Figure out where you are using log4j or a vulnerable product that uses log4j. Check the list at https://github.com/NCSC-NL/log4shell regularly because it is updated continuously!
Patch your software, or apply one of the mitigations mentioned in the link to the NCSC GitHub repo. Don’t forget: it’s not just internet-facing systems that can be attacked.
If you can’t patch or mitigate, make sure that a vulnerable server cannot make an internet connection as a temporary solution.
Configure your IDS and SIEM to block the IOCs and implement detection rules, again we refer to https://github.com/NCSC-NL/log4shell for this information (and keep it up to date because there are also many ways to bypass the detection rules).
If you have indications of compromise of a server, take the standard incident response and forensic measures: isolate, contain and investigate.
Asset Management
It is clear that most organizations are at risk currently since the exploit is so easy and the vulnerability so widespread. Knowing what you have (asset management) is extremely important and knowing what software components you use (SBOM)
OT Systems
Also, we expect not just IT systems, but also OT systems to be impacted by this vulnerability. Due to the often embedded nature of applications in OT environments, we expect it will take a lot longer to know and find out what OT products are especially vulnerable. But it is very plausible that OT data historians and loggers will turn out to be vulnerable.
Further Updates
We will update this page when new developments or information become relevant. For our customers, please contact your account manager if you have any questions concerning this vulnerability.