thinQtankLABS

Detection Engineering & Incident Response: CVE-2026-31431

Respond to a local privilege-escalation compromise on a shared Linux host (CVE-2026-31431). Reconstruct the timeline from auth and audit logs, find the attacker's sudoers persistence, engineer and tune a behavioral detection rule, then contain, eradicate, patch, verify and report.

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

Skills you will practice

  • Auth and audit log correlation
  • Timeline reconstruction
  • Privilege-escalation impact analysis
  • Indicators of compromise
  • Detection engineering and rule tuning
  • 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 Privilege-escalation techniques 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 Linux+ XK0-005 CISSP Certified Ethical Hacker (CEH) CEH Certified Incident Handler (E|CIH) E|CIH GCIH GCIH GCIA GCIA

The scenario

Yesterday the kernel bug was just a scanner finding. Overnight the SIEM correlated a local user opening a crypto socket from /tmp, then /etc/shadow being written, then a root shell. You are the responder. Classify it.

What you will do

  1. Open and classify the incident4 steps

    Open the incident folder · Read the correlated alert · Read the ticket · Classify the incident

  2. Reconstruct the timeline4 steps

    Pull the user’s auth events · When did root access appear? · Correlate the audit log · Which file was corrupted?

  3. Determine impact and persistence3 steps

    Inspect the sudoers drop-in · What persistence was planted? · Record the IOCs

  4. Engineer a detection rule4 steps

    Study the sample · Write a rule · Test and tune · Why behavior, not the username?

  5. Contain, eradicate, verify4 steps

    Remove the persistence · Patch the kernel · Verify the host · Confirm detection holds

  6. Report2 steps

    Write the report · Why eradicate before closing?

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.