thinQtankLABS

Detection Engineering & Incident Response: CVE-2026-42945

Respond to an NGINX worker-crash incident (CVE-2026-42945). Reconstruct the timeline from access and error logs, assess DoS versus RCE using the host ASLR setting, find the vulnerable rewrite config, engineer a detection rule, then contain with a config change, eradicate with an upgrade, verify and report.

Intermediate 21 guided steps 6 tasks About 75 minutes Runs in your browser

Skills you will practice

  • Access and error log correlation
  • Timeline reconstruction
  • DoS vs RCE impact assessment
  • Detection engineering
  • Compensating controls
  • Containment and eradication
  • Incident reporting

Certifications this lab maps to

This lab builds hands-on skills that appear on these certification exams. thinQtank Learning runs instructor-led training camps for each — click one to see upcoming classes.

CompTIA CySA+ CS0-003 Log analysis, detection and IR Training at thinQtank Learning EC-Council Certified Incident Handler E|CIH Incident-handling lifecycle Training at thinQtank Learning EC-Council Certified Ethical Hacker CEH Exploitation patterns and IOCs Training at thinQtank Learning ISC2 CISSP CISSP Security Operations domain Training at thinQtank Learning
Part of these certification lab packages: CySA+ CS0-003 CISSP Certified Ethical Hacker (CEH) CEH Certified Incident Handler (E|CIH) E|CIH GCIH GCIH GCIA GCIA

The scenario

An internet-facing NGINX proxy (CVE-2026-42945 open) had a burst of worker crashes right after crafted requests. You are the responder. Classify it.

What you will do

  1. Open and classify the incident4 steps

    Open the incident · Read the alert · Read the ticket · Classify it

  2. Reconstruct the timeline3 steps

    Pull the attacker’s requests · Correlate the error log · What signal killed the workers?

  3. Assess impact and find the trigger4 steps

    Check ASLR · Was RCE likely? · Find the vulnerable rewrite · Record IOCs

  4. Engineer a detection rule4 steps

    Study the sample · Write a rule · Test and tune · Why a run of '?', not any '?'

  5. Contain, eradicate, verify4 steps

    Contain: remove the trigger config · Eradicate: upgrade NGINX · Verify the host · Confirm detection holds

  6. Report2 steps

    Write the report · Config fix vs upgrade

How this lab works

A real Linux-style console. Commands run against real files, so hashes, hex dumps and comparisons give real results.

A file browser where you can place evidence into the lab, either the file provided or one of your own.

Reset a single step, a whole task or the entire lab. The environment is rebuilt so you can try again cleanly.

Progress saves after every step. Close the tab and come back later; your files and answers are waiting.