[Security][8.18] Document enhanced Linux process command line visibility

[benironside]

Description

On Linux systems with kernel versions below 5.10.16 (basically the systems that leverage kprobe for instrumentation), process command lines get cut off after 800 characters. This creates a security risk, attackers could hide malicious payloads by adding them after the 800 character limit.

We're going to change this behavior and need to document the new limits and truncation behavior.

Resources

https://github.com/elastic/security-team/issues/11339

Which documentation set does this change impact?

Elastic On-Prem and Cloud (all)

Feature differences

What release is this request related to?

8.18

Collaboration model

The documentation team

Point of contact.

Main contact: @nick-alayil

Stakeholders:

[nick-alayil]

This work has been completed for 8.18. It was initially targetted for Linux, but it looks like Defend Windows team has also applied the same approach for Windows.