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new(rules): Decoding Payload in Container #161

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Sep 12, 2023
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new(rules): Decoding Payload in Container #161

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23 changes: 23 additions & 0 deletions rules/falco-sandbox_rules.yaml
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Original file line number Diff line number Diff line change
Expand Up @@ -1712,3 +1712,26 @@
output: BPF Program Not Profiled (bpf_cmd=%evt.arg.cmd evt_type=%evt.type user=%user.name user_uid=%user.uid user_loginuid=%user.loginuid process=%proc.name proc_exepath=%proc.exepath parent=%proc.pname command=%proc.cmdline terminal=%proc.tty exe_flags=%evt.arg.flags %container.info)
priority: NOTICE
tags: [maturity_sandbox, host, container, mitre_persistence, TA0003]

- list: known_decode_payload_containers
items: []

- macro: base64_decoding
condition: (proc.cmdline contains "base64" and (proc.cmdline contains "--decode" or proc.cmdline contains "-d"))

- rule: Decoding Payload in Container
desc: >
Detect any use of {base64} decoding in a container. Legitimate applications may decode encoded payloads. The template list
known_decode_payload_containers can be used for simple tuning and customization, or you can adopt custom, more refined tuning. Less
sophisticated adversaries may {base64}-decode their payloads not only to obfuscate them, but also to ensure that the payload remains
intact when the application processes it. Note that injecting commands into an application's input often results in the application
processing passed strings like "sh -c". In these cases, you may be lucky and the encoded blob will also be logged. Otherwise, all you
will see is the {base64} decoding command, as the encoded blob was already interpreted by the shell.
condition: >
spawned_process
and container
and base64_decoding
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In general, rule is composed in a way that we can add more types of decoding as we see fit, for now only base64 decoding.

and not container.image.repository in (known_decode_payload_containers)
output: Decoding Payload in Container (evt_type=%evt.type user=%user.name user_uid=%user.uid user_loginuid=%user.loginuid process=%proc.name proc_exepath=%proc.exepath parent=%proc.pname command=%proc.cmdline terminal=%proc.tty exe_flags=%evt.arg.flags %container.info)
priority: INFO
tags: [maturity_sandbox, container, process, mitre_command_and_control, T1132]
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