I think almost every one of us working in the IR/Threat Intel area has faced this question at least once: shall we share intel information?

Although I have my own opinion on this, I will try to state some of the most common arguments I have heard in these years, pro and against sharing publicly, as objectively as possible not to influence the reader.

Why not sharing publicly?

• Many organizations do not share because do not want to give away the information that they (may) have been attacked or breached. On this regard, there are closed trusted groups of organizations within the same sector (e.g. ISAC communities) where the willingness to share in such closed environments increases.
• Trust is an extremely important factor within the intelligence community, and establishing trust is impossible when sharing publicly. Moreover, by not knowing with whom they are sharing, people are inclined to share less or not to share at all.
• Part of the community suggests that we should “stop providing our adversaries with free audits”[1], since in many occasions it has been observed a clear change within the TTP after the publications of analysis’ results on blogs or reports.

Why sharing publicly? 

• Relegating everything to sub communities may bring the problem of missing the big picture, since this may tend to create silos on the long term, and organizations relying entirely on them may miss the opportunity to correlate information shared from organizations belonging to other sectors.
• Many small organizations may not always be able to afford getting access to premium intelligence services, nor to enter in any of these closed sub-communities for several reasons. 
• Part of the community believes that we should share publicly because bad guys just don’t care and this is also proven by the fact that often times they reuse the same infrastructure and modus operandi.
• By sharing only within closed groups, those mostly affected would be DFIR people who uses such public information as their source of intel to understand if they have been compromised or not.

What is your view on this?

Pasquale

[1] – “When Threat Intel met DFIR”, http://archive.hack.lu/2015/When%20threat%20intel%20met%20DFIR.pdf