Mmcp.market

mid-engagement-ir-detection skill

by elementalsouls·elementalsouls/Claude-BugHunter·4.7k stars·MIT

Methodology for detecting client SOC patches, attacker activity, and security-state changes that occur DURING a red-team engagement — and converting those observations into deliverable findings. Built from authorized red-team work where the client patched a confirmed SQLi within 30 minutes of detection AND an external attacker locked multiple new accounts during a single test session. Use when (a) running ANY active engagement against a monitored target, (b) a previously-confirmed finding stops reproducing, (c) baseline timing shifts unexpectedly, or (d) you notice response patterns changing during testing.

A100/100content scan

Is the mid-engagement-ir-detection skill safe?

Clean: nothing in its files matched our rules. We read 1 file in the folder on 2026-09-28.

No findings.

Install the mid-engagement-ir-detection skill

A skill is a folder. Copy it into your agent's skills folder and the agent loads it when the task matches its description. 

git clone --depth 1 https://github.com/elementalsouls/Claude-BugHunter.git /tmp/Claude-BugHunter
mkdir -p ~/.claude/skills
cp -r /tmp/Claude-BugHunter/skills/mid-engagement-ir-detection ~/.claude/skills/mid-engagement-ir-detection
available in every project

In the Claude apps, zip the folder and upload it from the Skills settings. The folder on GitHub

The instructions your agent would load

SKILL.md as published, without the frontmatter. Read it on GitHub

When to use this skill

Trigger when:

  • Running active testing against a target with active SOC monitoring
  • A confirmed-vulnerable finding stops reproducing on recheck
  • Baseline timing shifts unexpectedly (3× slower, sudden errors, new headers)
  • Response sizes change between test windows
  • New WAF cookies or headers appear that weren't there at session start
  • Lockout / error rates change between test windows (especially LOCKED count for credential attacks)
  • Engagement is "assume breach" or "white box" — client knows you're testing

DO NOT use for:

  • Bug bounty (client doesn't know you're there; no real-time IR)
  • Pure recon (no state-change happening)
  • One-off vulnerability scanning (no temporal dimension)

The core insight

In a real red-team engagement against a competent SOC, the security state of the target is not static. It changes during your test in response to your traffic. These state changes are:

  1. Themselves valuable findings (positive operational observations about IR responsiveness)
  2. Confirmation evidence (mid-engagement patch = the original vulnerability was real)
  3. Classification signals (WAF rule deployment vs code fix — different remediation depth)

Anti-pattern: treating reproduction failure as evidence the original signal was a false positive. Original PoC artifacts captured before the change are still the vulnerability finding.

The discipline — capture before, diff after

Before any active test:

# Capture pre-test fingerprint of the target
fingerprint = {
    "ts_pre": time.time(),
    "ip_seen": "<operator-src-ip>",
    "baseline_response_time_ms": <measure>,
    "baseline_response_size_bytes": <measure>,
    "response_headers": <capture set>,
    "waf_cookies": <list>,
    "lockout_count_in_state": <count from o365_attempts.json>,
}

Persist to engagementlog/fingerprintpre.json.

During the test:

Log every test result with full context (timestamp, IP, payload, response code, response size, response time, headers if relevant) to JSONL append-only.

After the test session OR on first failed-recheck:

fingerprint_post = same structure
delta = {
    "baseline_time_change_ms": post.time - pre.time,
    "baseline_size_change_bytes": post.size - pre.size,
    "new_headers_appeared": post.headers - pre.headers,
    "new_waf_cookies": post.cookies - pre.cookies,
    "new_lockouts": post.locked_count - pre.locked_count,
}

If any delta is significant — investigate, don't retract.

The three primary IR observations

Observation 1 — Mid-engagement WAF rule deployment

Symptoms:

  • Original payloads return identical response → no signal at all on recheck
  • Body size identical to baseline (login page reflection)
  • Timing reverts to baseline regardless of payload
  • New cookie or header in responses (e.g., cf-bm, cfbm, awselb)
  • Specific keyword in URL/body now triggers different response code (403, 406, 429)

Confirmation: retry with WAF-evasion variants:

  • URL-encode the payload differently (%27 vs %5cu0027)
  • Change request method (POST → PUT, GET → POST)
  • Different content-type (form-urlencoded → multipart)
  • Slower pace (5s → 60s between requests)
  • Mixed-case keywords (SLEEP → SlEeP)

If WAF-evasion variants restore the signal, the mitigation is at the WAF layer (bypassable).

If even WAF-evasion variants stay blocked, the mitigation is likely in code.

Finding template:

Subject: Mid-engagement mitigation deployed for <vulnerability X>
Observation: At engagement timestamp T0, vulnerability <X> on <endpoint> was
confirmed via <PoC>. At T0+<minutes>, recheck via the original payload no longer
reproduces the timing/error/size differential. <WAF-evasion variant> [does/does
not] restore the signal.

Description: This pattern is consistent with the client SOC observing engagement
traffic and deploying a mitigation in real time. Mitigation depth assessment:
[at-WAF, bypassable] vs [in-code, durable].

Impact (positive): Client SOC has both detection-grade visibility into application
traffic AND the authority to deploy mitigations within ~<minutes> of detection.

Impact (caveat): The original vulnerability did exist and was exploitable for at
least the engagement window before mitigation. If the mitigation is at the WAF
layer only, the underlying code-level flaw remains exploitable via alternative
payloads.

Recommendation:
1. Verify the mitigation is in code (parameterized queries, input sanitization),
   not just at the WAF layer.
2. Audit the codebase for the same root cause across sister applications.
3. (Positive) Document the IR responsiveness as a c

Observation 2 — Active concurrent attacker

Symptoms:

  • Many AADSTS50053 (LOCKED) responses despite your 1-attempt-per-user discipline
  • Lockouts cluster alphabetically or by some other sort key
  • New lockouts appear DURING your engagement (diff before/after)
  • LOCKED rate exceeds expected baseline (in our engagement: 11% of all attempts → red flag)

Math check:

  • Your discipline: 1 attempt per user lifetime
  • Smart Lockout default: lockout after 10 failed attempts; lockout duration starts at 60 seconds and grows with each subsequent lockout (not a flat 10-minute window)
  • Therefore: IF tool logs confirm exactly 1 attempt/user (no burst retries, no parallel-goroutine duplicate sends, no tool misconfiguration), you cannot mathematically cause Smart Lockout — verify journal.jsonl shows 1 attempt/user before asserting this
  • Therefore: every NEW AADSTS50053 accumulating during the window (per before/after diff) was caused by someone else; pre-existing locks may stem from the legitimate user's own failures or a prior test run, so attribute only the newly-accumulating locks to an external party

Confirmation:

  • Sort locked accounts alphabetically; if they cluster, attacker is using sorted username list
  • Compare pre-session lockout count vs post-session — new locks during your session = attacker is active right now
  • Probe a known-active "system" account (noreply@, info@, oc@) — if it's locked, attacker is hitting service mailboxes too (typically MFA-exempt → high-value to attackers)

Finding template:

Subject: Active external password-spray campaign detected during engagement

Observation: During M365 ROPC validation against the <tenant> Entra tenant, <N>
unique principals returned AADSTS50053 (Smart Lockout) when probed with a single
password attempt at safe pace. Our tool journal (journal.jsonl) confirms exactly
1 attempt per user with no duplicate sends, so under the Smart Lockout default
(lockout after 10 failed attempts) we cannot have caused these lockouts. The
attribution below applies to the <K> NEW locks that accumulated during our
engagement window between <timestamp_start> and <timestamp_end> (per before/after
diff); pre-existing locks are not attributed to this campaign.

Description: The pattern (alphabetical clustering, real-time accumulation,
including system mailboxes) is consistent with an external attacker performing
a username-list-driven password spray attack against the tenant.

Impact: An external adversary is actively attempting to compromise corporate
M365 accounts. The attacker has knowledge of the user-email schema and a
password-guess wordlist. <List of locked accounts is now in attacker's hands>
(Smart Lockout differentiates valid from invalid usernam

Observation 3 — Detection-induced rate limiting / IP blocks

Symptoms:

  • Specific IP starts returning 403 / 429 / 451 after a window of normal responses
  • Specific IP starts seeing dramatically slower responses (3x+ baseline)
  • TLS handshake fails or RST mid-connection
  • DNS suddenly returns NXDOMAIN for hosts that resolved before
  • Some hosts work from one IP but not another

Confirmation:

  • Rotate to a different IP and retry — if works, you got rate-limited/blocked
  • Compare TTL on DNS responses — sudden short TTL = active mitigation deployed
  • Check Server:, Via:, CF-Cache-Status: headers for CDN-introduced limits

Finding template (operational note, usually low/info severity):

Subject: Engagement traffic detected — IP <X> rate-limited at <timestamp>

Observation: After ~<N> requests in <window> from IP <X>, target <hostname>
began returning <code> for all subsequent requests. Rotation to IP <Y>
restored normal responses.

Description: Active anti-automation control at the perimeter (CDN/WAF/origin).

Impact (positive): Volumetric anti-automation is functional.

Impact (caveat): Rotation defeats this control trivially (cloud VMs cost <$5).
A patient adversary or spray-from-residential-proxies attacker is not affected.

State diff — the key technique

Maintain three pieces of state:

1. engagement_log/baseline.json — captured at session start

{
  "ts": "2026-05-08T13:00:00",
  "source_ip": "<operator-src-ip>",
  "targets": {
    "https://target.example.com/login": {
      "baseline_response_time_ms": 584,
      "baseline_response_size_bytes": 11966,
      "headers_seen": ["Server: Apache", "X-Powered-By: PHP/8.0.26"],
      "set_cookie_names": ["PHPSESSID"]
    }
  },
  "m365": {
    "lockout_count": 247,
    "valid_creds_count": 0
  }
}

2. engagement_log/journal.jsonl — append-only test log

Every test logs:

{"ts":"...","ip":"...","tool":"...","target":"...","payload":"...","resp_code":...,"resp_size":...,"resp_ms":...,"verdict":"...","notes":"..."}

3. engagementlog/statechanges.jsonl — observed deltas

When a state change is detected, append:

{"ts_observed":"2026-05-08T14:30:00","change_type":"baseline_time_shift","target":"https://<employee-app-host>/<app>/login.php","baseline_pre_ms":24412,"baseline_post_ms":90403,"interpretation":"likely WAF rule deployed","actions_taken":["tested WAF-evasion variants — no signal restoration","documented as IR-mitigation finding"]}

This third file is your finding evidence. Every entry is a candidate finding.

Tooling — automated state-change detection

# Bash watcher — runs every 5 min during engagement, alerts on shifts

cd "$ENGAGEMENT_DIR"

# Re-measure baseline timing on key targets
for target in "$@"; do
  ms=$(curl -sk -o /dev/null -w "%{time_total}" "$target" --max-time 30)
  ms_int=$(echo "$ms * 1000" | bc | cut -d. -f1)
  echo "$(date -u +%FT%TZ) $target $ms_int" >> baseline_history.log
done

# Diff against pre-session baseline
python3 - << 'PY'
import json, time
baseline = json.load(open("engagement_log/baseline.json"))
for line in open("baseline_history.log"):
    parts = line.strip().split()
    ts, target, ms = parts[0], parts[1], int(parts[2])
    if target in baseline["targets"]:
        pre = baseline["targets"][target]["baseline_response_time_ms"]
        if abs(ms - pre) > pre * 0.5:  # >50% shift
            print(f"ALERT {ts} {target} time {pre} -> {ms}")
PY

For lockout-count tracking on M365:

# Run every 30 min during M365 spray
LOCK_COUNT=$(grep -c '"AADSTS50053"' engagement_log/o365_results.jsonl)
echo "$(date -u +%FT%TZ) lockout_count $LOCK_COUNT" >> lockout_history.log
# Diff first vs last to surface delta

The "single signal recanted" rule

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