TaoSecurity Blog

This is a quick note to point blog readers to my Zeek in Action YouTube video series for the Zeek network security monitoring project .  Each video addresses a topic that I think might be of interest to people trying to understand their network using Zeek and adjacent tools and approaches, like Suricata, Wireshark, and so on.  I am especially pleased with Video 6 on monitoring wireless networks . It took me several weeks to research material for this video. I had to buy new hardware and experiment with a Linux distro that I had not used before -- Parrot .  Please like and subscribe, and let me know if there is a topic you think might make a good video.

Are you a network security monitoring dinosaur like me? Do you prefer to inspect your Zeek logs using the command line instead of a Web-based SIEM? If yes, try this one weird trick! I store my Zeek logs in JSON format. Sometimes I like to view the output using jq. If I need to search directories of logs for a string, like a UID, I might* use something like zgrep with the following syntax: $ zgrep "CLkXf2CMo11hD8FQ5" 2020-08-16/* 2020-08-16/conn_20200816_06:00:00-07:00:00+0000.log.gz:{"_path":"conn","_system_name":"ds61","_write_ts":"2020-08-16T06:26:10.266225Z","_node":"worker-01","ts":"2020-08-16T06:26:01.485394Z","uid":"CLkXf2CMo11hD8FQ5","id.orig_h":"192.168.2.76","id.orig_p":53380,"id.resp_h":"196.216.2.24","id.resp_p":21,"proto":"tcp","service":"ftp",...

I spent a chunk of the day troubleshooting a network security monitoring (NSM) problem. I thought I would share the problem and my investigation in the hopes that it might help others. The specifics are probably less important than the general approach. It began with ja3 . You may know ja3 as a set of Zeek scripts developed by the Salesforce engineering team to profile client and server TLS parameters. I was reviewing Zeek logs captured by my Corelight appliance and by one of my lab sensors running Security Onion. I had coverage of the same endpoint in both sensors. I noticed that the SO Zeek logs did not have ja3 hashes in the ssl.log entries. Both sensors did have ja3s hashes. My first thought was that SO was misconfigured somehow to not record ja3 hashes. I quickly dismissed that, because it made no sense. Besides, verifying that intution required me to start troubleshooting near the top of the software stack. I decided to start at the bottom, or close to the bottom. I ha...