1. Overview

Prisma Cloud lets you create runtime rules that block discrete processes inside a container. It is an alternative to stopping an entire container when the violation of a runtime rule is detected.

2. Capabilities

Prisma Cloud runtime rules let you deny specific processes. When you specify the Prevent action in a runtime rule, Prisma Cloud blocks containers from running processes that are not defined in the model or the explicitly allowed processes list. The rest of the container continues to execute without disruption. The alternative to discrete blocking is container blocking, which stops the entire container when a denied process is detected.

The Prevent action is not supported on Debian 8.

Prisma Cloud also lets you deny file system writes to specific directories. Like the process rule, file system rules can be configured with the Prevent action, which blocks the creation and modification of any files in the specified directories. This mechanism is designed to prevent bad actors from writing certificates or binary attack tools to disk, all without killing the process that initiated the write or stopping the entire container.

The Prevent action for host file system rules requires a Linux kernel version 4.20 or later.
The Prevent action in file system rules is not supported when the Docker storage driver is set to aufs. It is supported for other storage drivers, such as devicemapper and overlay2. If you specify a Prevent action, but the storage driver does not support it, Prisma Cloud will respond with an alert and log the following message in Defender’s log: "Docker storage driver on host doesn’t support discrete file blocking"

3. Creating discrete blocking rules

Discrete blocking rules are created under Defend > Runtime.

Runtime rules have both a Process and a File System tab. These tabs let you configure the following effects:

Disable

Deactivates the runtime sensor.

Alert

Logs an event for a violation. For process rules, the process continues to run. For file system rules, the file system write is permitted.

Prevent

For process rules, the process is killed. For file system rules, the file write is prevented.

Block

Stops the entire container when a violation is detected.

  1. Open Console

  2. Go to Defend > Runtime > Container Policy.

  3. Click Add rule.

  4. In the General tab, specify a rule name.

  5. Click on the Processes tab.

  6. Under Effect, select Prevent.

  7. In Explicitly denied processes, specify a list of process names or MD5 hashes for processes that should be blocked from running.

  8. Click Save.