Move threat model doc to GitHub

Move threat model doc to GitHub
Sort of, but needs more detail. The Monitor Server cannot directly log in to the App Server (say via SSH). However, it can trigger arbitrary commands to be executed by the OSSEC agent user. This user is pretty locked down though, see: http://www.ossec.net/?page_id=169 You would need privilege escalation vulnerabilities to do much beyond mess with monitoring (which you could already do if you had access to the monitor server).

OSSEC has an [active response](http://ossec-docs.readthedocs.org/en/latest/syntax/head_ossec_config.active-response.html) feature, which could theoretically be leveraged by an attacker to do more, but we do not enable it.