This is a three-part blog about OPSEC for Blue Teams. This first part expresses some of my ideas about the risk of alerting the adversary and OPSEC for getting OSINT and context on domains and IPs. The second part is about testing tools (I performed tests on PassiveTotal and VirusTotal) which provide context and/or OSINT in relation to OPSEC. The last part will be on sandboxes, secure communications and sharing of info & data when dealing with a targeted attack.

When talking about adversaries in this series, I mean the ones which are targeting your company. So I do not discuss a threat actor executing a malware or phishing campaign against a large and diverse group of victims. You can be less strict on following certain OPSEC rules when you know you deal with a non-targeted attack. Still, following secure practices in both cases will make sure your default behaviour is in line with good OPSEC rules.