Lion Cipher Lab
Cut false-positive IOCs with MISP warninglists
- Threat Intel Analyst
- Intermediate
- ~40 min
- Free · no account required
Why it matters
The fastest way to cause an outage with threat intelligence is to push a raw list of extracted indicators straight into a blocklist. Buried in that list are your own DNS resolver, a private IP range, and a CDN that half the internet rides on — block those and you take down name resolution or a business-critical site, then drown the analyst in noise. MISP warninglists are the free, offline hygiene gate that catches those known-benign values before they hurt you. Running that gate, and understanding why it is triage and not truth, is a core threat-intel skill.
What you'll learn
- IOC hygiene
- false-positive reduction
- MISP warninglists
- CIDR matching in Python
- triage judgment
Steps in this lab
- The problem: raw IOCs are dangerous to block
- What a warninglist is
- Clone the dataset (one command, then offline)
- Understand the match `type` — this is the whole trick
- Build a realistic dirty IOC list
- Write the filter script
- Run it and read the measured before/after
- The judgment: a gate, not an oracle