It's resally common knowledge if you work as a Cyber crime responder or visit some of those forums (e.g. breachforums). Krebs of course has to have a few good contacts in those circles.
From Europol:
> Violent online groups are targeting and manipulating vulnerable children and young people across widely accessible online platforms. There are multiple groups, associations and evolving subgroups that make up the online network known as The Com – short for community. The Com is a virtual community of groups and individuals who conduct illicit activities that glorify serious violence, cruelty, and gore.
> Elements of The Com network are known to have extreme ideological views and victimise children, coercing them to commit violent acts. Predators groom their victims through different methods – one approach is establishing friendships based on trust or romantic relationships. Another technique involves the use of power or coercive tactics with one goal – taking control over the victims, while getting them to engage in serious violence, self-harm, or other gruesome. It’s a vicious cycle - the predators in this network influence children or young people into conducting acts that increasingly shame, incriminate, or isolate them, this in turn makes them more vulnerable to further exploitation.
https://www.europol.europa.eu/media-press/newsroom/news/law-...