Falco is a behavioral activity monitor designed to detect anomalous activity in your applications. Powered by sysdig’s system call capture infrastructure, Falco lets you continuously monitor and detect container, application, host, and network activity… all in one place, from one source of data, with one set of rules.
Falco is hosted by the Cloud Native Computing Foundation (CNCF) as a sandbox level project. If you are an organization that wants to help shape the evolution of technologies that are container-packaged, dynamically-scheduled and microservices-oriented, consider joining the CNCF. For details read the Falco CNCF project proposal.
What kind of behaviors can Falco detect?
Falco can detect and alert on any behavior that involves making Linux system calls. Thanks to Sysdig’s core decoding and state tracking functionality, Falco alerts can be triggered by the use of specific system calls, their arguments, and by properties of the calling process. For example, you can easily detect things like:
- A shell is run inside a container
- A container is running in privileged mode or is mounting a sensitive path like /proc from the host.
- A server process spawns a child process of an unexpected type
- Unexpected read of a sensitive file (like /etc/shadow)
- A non-device file is written to /dev
- A standard system binary (ls) makes an outbound network connection
How you use it
Falco is deployed as a long-running daemon. You can install it as a Debian/rpm package on a regular host or container host, or you can deploy it as a container.
Falco is configured via a rules file defining the behaviors and events to watch for, and a general configuration file. Rules are expressed in a high-level, human-readable language. We’ve provided a sample rule file ./rules/falco_rules.yaml as a starting point – you can (and will likely want!) to adapt it to your environment.
When developing rules, one helpful feature is Falco’s ability to read trace files saved by sysdig. This allows you to “record” the offending behavior once, and replay it with Falco as many times as needed while tweaking your rules.
Once deployed, Falco uses the Sysdig kernel module and userspace libraries to watch for any events matching one of the conditions defined in the rule file. If a matching event occurs, a notification is written to the configured output(s).
When Falco detects suspicious behavior, it sends alerts via one or more of the following channels:
- Writing to standard error
- Writing to a file
- Writing to syslog
- Pipe to a spawned program. A common use of this output type would be to send an email for every Falco notification.
More details on these alerts are described [here](Falco Alerts).
- Support for K8s Audit Events : Falco now supports K8s Audit Events as a second stream of events in addition to syscalls. For full details on the feature, see the wiki.
- Transparent Config/Rule Reloading: On SIGHUP, Falco will now reload all config files/rules files and start processing new events. Allows rules changes without having to restart falco [#457] [#432]
- The reference integration of falco into a action engine now supports aws actions like lambda, etc. [#460]
- Add netcat to falco docker images, which allows easier integration of program outputs to external servers [#456] [#433]
- Links cleanup related to the draios/falco -> falcosecurity/falco move [#447]
- Properly load/unload kernel module when the falco service is started/stopped [#459] [#418]
- Better coverage (e.g. reduced FPs) for critical stack, hids systems, ufw, cloud-init, etc. [#445]
- New rules
Launch Package Management Process in Container,
Netcat Remote Code Execution in Container, and
Lauch Suspicious Network Tool in Containerlook for running various suspicious programs in a container. [#461]
- Misc changes to address false positives in GKE, Istio, etc. [#455] [#439]
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