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from the cat-and-mouse-and-dogged-determination dept.
A couple years ago I set up a simple brochure-ware site for the School Board in the district here in Brooklyn, hosted on a VPS instance on Linode, to publicize the dates of public meetings, meeting minutes, etc. The VPS doesn't contain any sensitive information so I locked down the ports to 80, 443, and 22, hardened the SSH with measures like fail2ban, kept the system updated every week or so, and called it a day.
Last week, though, the site was compromised. Blowing the instance away and re-creating it from physical backups is not a problem, but in poring through the system to figure out how it was breached I realized both that my own security chops aren't deep enough and that standard best security practices might not be good enough anymore, anyway, given the many vulnerabilities exposed in the last year and realities like the NSA trove that Shadow Brokers leaked.
So the question for the more experienced security professionals in the Soylent community is, can they recommend a good guide and/or site to hone linux security chops and forensic skills that's current?
(Score: 2, Insightful) by Anonymous Coward on Sunday June 04 2017, @12:49AM
You are probably making the most basic mistake when doing the triage. You are still trusting the machine. Do not trust any of the tools on the machine to give you an honest answer. A few tools that may give you anywhere close to a reliable answer is to compare the contents of /proc to what the tools report (missing PIDs, cmdline files, etc), rkhunter and chkrootkit on both the machine and a live cd, comparing hashes using a tool like rpm -V, hashing all files on the computer and comparing them to the hashes made by the tools on a live cd. Basically, once your computer is compromised, verify the trust you give it as anything can be changed by an adversary with enough privileges.