Project: KubeArmor (Provisioning / Security & Compliance)
File: host_security_policy_specification.md

Here is the specification of a host security policy. ```text apiVersion: security.kubearmor.com/v1 kind:KubeArmorHostPolicy metadata: name: [policy name] spec: severity: [1-10] # --> optional (1 by default) tags: ["tag", ...] # --> optional message: [message] # --> optional nodeSelector: matchLabels: process: matchPaths: path: [absolute executable path] ownerOnly: [true|false] # --> optional fromSource: # --> optional path: [absolute exectuable path] matchDirectories: dir: [absolute directory path] recursive: [true|false] # --> optional ownerOnly: [true|false] # --> optional fromSource: # --> optional path: [absolute exectuable path] matchPatterns: pattern: [regex pattern] ownerOnly: [true|false] # --> optional file: matchPaths: path: [absolute file path] readOnly: [true|false] # --> optional ownerOnly: [true|false] # --> optional fromSource: # --> optional path: [absolute exectuable path] matchDirectories: dir: [absolute directory path] recursive: [true|false] # --> optional readOnly: [true|false] # --> optional ownerOnly: [true|false] # --> optional fromSource: # --> optional path: [absolute exectuable path] matchPatterns: pattern: [regex pattern] readOnly: [true|false] # --> optional ownerOnly: [true|false] # --> optional network: matchProtocols: protocol: [TCP|tcp|UDP|udp|ICMP|icmp] fromSource: path: [absolute exectuable path] capabilities: matchCapabilities: capability: [capability name] fromSource: path: [absolute exectuable path] action: [Audit|Block] (Block by default) ``` Note Please note that for system calls monitoring we only support audit action no matter what the value of action is For better understanding, you can check . Now, we will briefly explain how to define a host security policy. Common A security policy starts with the base information such as apiVersion, kind, and metadata. The apiVersion and kind would be the same in any security policies. In the case of metadata, you need to specify the name of a policy. ```text apiVersion: security.kubearmor.com/v1 kind: KubeArmorHostPolicy metadata: name: [policy name] ``` Make sure that you need to use `KubeArmorHostPolicy`, not `KubeArmorPolicy`. Severity You can specify the severity of a given policy from 1 to 10. This severity will appear in alerts when policy violations happen. ```text severity: [1-10] ``` Tags The tags part is optional. You can define multiple tags (e.g., WARNING, SENSITIVE, MITRE, STIG, etc.) to categorize security policies. ```text tags: ["tag1", ..., "tagN"] ``` Message The message part is optional. You can add an alert message, and then the message will be presented in alert logs. ```text message: [message] ``` NodeSelector The node selector part is relatively straightforward. Similar to other Kubernetes configurations, you can specify \(a group of\) nodes based on labels. ```text nodeSelector: matchLabels: ``` If you do not have any custom labels, you can use system labels as well. ```text kubernetes.io/arch: [architecture, (e.g., amd64)] kubernetes.io/hostname: [host name, (e.g., kubearmor-dev)] kubernetes.io/os: [operating system, (e.g., linux)] ``` Process In the process section, there are three types of matches: matchPaths, matchDirectories, and matchPatterns. You can define specific executables using matchPaths or all executables in specific directories using matchDirectories. In the case of matchPatterns, advanced operators may be able to determine particular patterns for executables by using regular expressions. However, we generally do not recommend using this match. ```text process: matchPaths: path: [absolute executable path] ownerOnly: [true|false] # --> optional fromSource: # --> optional path: [absolute executable path] matchDirectories: dir: [absolute directory path] recursive: [true|false] # --> optional ownerOnly: [true|false] # --> optional fromSource: # --> optional path: [absolute exectuable path] matchPatterns: pattern: [regex pattern] ownerOnly: [true|false] # --> optional ``` In each match, there are three

ownerOnly \(static action: allow owner only; otherwise block all\) If this is enabled, the owners of the executable\(s\) defined with matchPaths and matchDirectories will be only allowed to execute. recursive If this is enabled, the coverage will extend to the subdirectories of the directory defined with matchDirectories. fromSource If a path is specified in fromSource, the executable at the path will be allowed/blocked to execute the executables defined with matchPaths or matchDirectories. For better understanding, let us say that an operator defines a policy as follows. Then, /bin/bash will be only allowed (blocked) to execute /bin/sleep. Otherwise, the execution of /bin/sleep will be blocked (allowed). ```text process: matchPaths: path: /bin/sleep fromSource: path: /bin/bash ``` File The file section is quite similar to the process section. ```text file: matchPaths: path: [absolute file path] readOnly: [true|false] # --> optional ownerOnly: [true|false] # --> optional fromSource: # --> optional path: [absolute file path] matchDirectories: dir: [absolute directory path] recursive: [true|false] # --> optional readOnly: [true|false] # --> optional ownerOnly: [true|false] # --> optional fromSource: # --> optional path: [absolute file path] matchPatterns: pattern: [regex pattern] readOnly: [true|false] # --> optional ownerOnly: [true|false] # --> optional ``` The only difference between 'process' and 'file' is the readOnly option. readOnly \(static action: allow to read only; otherwise block all\) If this is enabled, the read operation will be only allowed, and any other operations \(e.g., write\) will be blocked. Network In the case of network, there is currently one match type: matchProtocols. You can define specific protocols among TCP, UDP, and ICMP. ```text network: matchProtocols: protocol: [protocol(,)] # --> [ TCP | tcp | UDP | udp | ICMP | icmp ] fromSource: path: [absolute file path] ``` Capabilities In the case of capabilities, there is currently one match type: matchCapabilities. You can define specific capability names to allow or block using matchCapabilities. You can check available capabilities in . ```text capabilities: matchCapabilities: capability: [capability name(,)] fromSource: path: [absolute file path] ``` Syscalls In the case of syscalls, there are two types of matches, matchSyscalls and matchPaths. matchPaths can be used to target system calls targeting specific binary path or anything under a specific directory, additionally you can slice based on syscalls generated by a binary or a group of binaries in a directory. You can use matchSyscall as a more general rule to match syscalls from all sources or from specific binaries. ``` syscalls: matchSyscalls: syscall: syscallX syscallY fromSource: # --> optional path: [absolute exectuable path] dir: [absolute directory path] recursive: [true|false] # --> optional matchPaths: path: [absolute directory path | absolute exectuable path] recursive: [true|false] # --> optional syscall: syscallX syscallY fromSource: # --> optional path: [absolute exectuable path] dir: [absolute directory path] recursive: [true|false] # --> optional ``` There is one options in each match. fromSource If a path is specified in fromSource, kubearmor will match only syscalls generated by the defined source. For better undrestanding, lets take the example below. Only unlink system calls generated by `/bin/bash` will be matched. ```text process: matchPaths: path: /bin/sleep syscall: unlink fromSource: path: /bin/bash ``` recursive If this is enabled, the coverage will extend to the subdirectories of the directory. Action The action could be Audit or Block in general. In order to use the Allow action, you should define 'fromSource'; otherwise, all Allow actions will be ignored by default. ```text action: [Audit|Block] ``` If 'fromSource' is defined, we can use all actions for specific rules. ```text action: [Allow|Audit|Block] ``` For System calls monitoring, we only support audit mode no matter what the action is set to.