An "RDP connection to DC" investigation arrived with device {}, process {} and
two indexed entities, both of them false — the 32-hex tails of its own alert
RRNs, which the IOC regex cannot tell from an MD5. Its four real values were
sitting in the payload, unmapped:
source_account vbalbakakis
destination_account vassilisadmin
source_asset_address sgazswvdip-01.toto.priv
destination_asset_address scazsvpdc01.toto.priv
The mappings assumed an alert has one host and one user, which holds for a
process_start_event and not for an auth rule: a connection names both ends and
neither is "the host". So source and destination now land on src_endpoint and
dst_endpoint, the acting account on actor.user and the account acted upon on
user — the distinction that lets a lateral move be read in one line.
That choice is also what makes the fields placeable. The layout builder's field
picker is a closed <select> over the OCSF catalogue in web/src/lib/ocsf.ts;
a path absent from it cannot be put on a layout at all. All four targets are in
that catalogue. `detection`, the open-vocabulary catch-all, is not and cannot
be — it keeps its value in the Context tab, which renders the whole tree, but a
layout cannot reference it, so anything meant for a layout has to be mapped to a
real OCSF field first.
evidences[] is flattened at the same time. It emitted "device": {}, "process":
{} and "attacks": {"technique": {}} whenever those keys were absent — three
empty objects per alert, filling the context and hiding what was populated.
Verified against the RDP investigation: four entities where there were none,
two hosts and two accounts, and no false hash once the incident type's
extraction policy is set to selected/host,ip,user.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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