Image-mode RHEL moves the host into an ostree-backed, container-built world. The threat model shifts up the stack, and most detection content built for traditional EL hosts quietly stops working.
A defender-oriented look at the SharePoint ToolShell chain (CVE-2025-53770 / 53771) — what the telemetry actually looks like in a real SIEM, where the first round of tuning breaks, and which assumptions about your SharePoint farm change the answer.
Continuous Access Evaluation and Device Bound Session Credentials closed some of the AitM gap, but session token theft against Entra ID is still the dominant identity attack and most of the detection burden still falls on the SOC. Here is the shape of the problem and where the first round of tuning has to land.
Token Protection and DBSC closed some doors in 2026 but left the SOC with a messier detection surface than the vendor decks suggest. Here is what the incident actually looks like in the SIEM, where the first round of tuning has to land, and what most teams get wrong on revocation.
A Nightwing contractor with CISA access kept a public GitHub repository called Private-CISA from November 13, 2025 to May 15, 2026 — 184 days of admin credentials to three AWS GovCloud accounts, Entra ID SAML certificates, Artifactory tokens, plaintext passwords in CSV, and the Landing Zone DevSecOps configuration for the agency tasked with everyone else’s vulnerability hygiene. The leak is bad. The thing that should worry defenders more is that the AWS keys remained valid for 48 hours after CISA was notified.
CVE-2026-42897 is an actively exploited OWA cross-site-scripting flaw in Microsoft Exchange Server 2016, 2019, and Subscription Edition. CVSS 8.1, KEV-listed, federal remediation deadline May 29. A specially crafted email runs JavaScript in the victim’s OWA session — session token theft, mailbox read, send-as, mailbox rules — and the catch buried in Microsoft’s guidance is that a permanent patch is gated behind Period 2 ESU enrollment for everyone still on 2016 or 2019. The EEMS mitigation works, with caveats. Here’s what’s real about it.
A defender’s view of the Famous Chollima / Nickel Tapestry IT worker scheme as it looks in 2026 — the telemetry that actually catches it, the false positives that swamp you in week one, and where it sits in the 800-53 catalog.
TeamPCP — the supply-chain crew behind the Trivy / Checkmarx / KICS / LiteLLM compromises and the Shai-Hulud worm — surfaced a sale listing on May 19, 2026 claiming roughly 4,000 GitHub private repositories of internal source code. The claim is pending verification, the ESIX score is 7.96, and the group’s track record is exactly the mix of ‘demonstrably capable’ and ‘inclined to repackage’ that makes this kind of listing operationally annoying. Here’s the read.
A defender-side look at where PRC pre-positioning campaigns against critical infrastructure stand heading into 2026, what living-off-the-land actually looks like in the SIEM, and which tuning calls separate the teams that catch it from the teams that don’t.
Image-mode RHEL and bootc move /usr to a read-only ostree commit and turn host updates into container pulls. That fixes one class of problem and creates a different one for defenders. Here is what actually changes on disk, what to detect, and where the model breaks.
