Falco: A cloud-native security tool
Falco
Falco is a cloud-native security tool. It provides near real-time threat detection for cloud, container, and Kubernetes workloads by leveraging runtime insights. Falco can monitor events defined via customizable rules from various sources, including the Linux kernel, and enrich them with metadata from the Kubernetes API server, container runtime, and more. Falco supports a wide range of kernel versions, x86_64 and ARM64 architectures, and many different output channels.
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).
Falco Alerts
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.
Install & Tutorial
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