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name: hunt-session description: "Hunt Session Management vulnerabilities — session fixation (no regeneration on login), insufficient invalidation on logout / password-change / email-change, predictable or low-entropy session IDs, JWT-as-session with no exp/revocation, refresh-token rotation/reuse-detection gaps, OAuth/SSO session linkage, device-bound-session (DBSC) downgrade, and cookie attribute issues (Secure/HttpOnly/SameSite/__Host-). Validate with TWO real sessions (attacker A + victim B), body-diff every 200, and OOB confirmation for theft chains. Medium to Critical (fixation→admin hijack, no-invalidation→persistent ATO)." sources: hackerone_public, portswigger_research, owasp_wstg report_count: 18

Autonomous Testing Priority

Missing HttpOnly on cookies is auto-detected — focus your active testing on lifecycle invalidation (higher impact).

Pattern 1 — Session survives logout (most common high-value finding):

1. Login and note the session token/cookie value
2. Call the logout endpoint (/logout, POST /api/logout, etc.)
3. Try to use the OLD session token to access a protected resource (/api/me, /dashboard, /account)
4. If 200 with user data → session not invalidated on logout = ATO persistence

Pattern 2 — Session not regenerated on login (session fixation):

1. GET any page to receive a pre-authentication session token/cookie
2. POST valid credentials to the login endpoint
3. Compare the session token BEFORE and AFTER login
4. If the token is unchanged → session fixation vulnerability

Pattern 3 — Session survives password change:

1. Login → record session A value
2. Change the password via the account settings endpoint
3. Replay session A on a protected endpoint
4. If 200 → token not rotated on credential change = persistent ATO (critical chain when combined with XSS/cookie theft)

Content-type: Login and session endpoints vary — use application/json for REST APIs, application/x-www-form-urlencoded for traditional web forms. Try both if the first returns an unexpected response.

Proof: A protected-resource 200 response (with user data) using a session token that should have been invalidated confirms the finding.

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HUNT-SESSION — Session Management

Crown Jewel Targets

Session fixation leading to admin hijack = Critical. Session surviving a password change = High-to-Critical (persistent ATO from a stolen cookie that the victim believes they revoked by resetting their password).

Highest-value chains:

• Session fixation — server accepts a session ID set by the client and does NOT regenerate it on login → attacker pre-plants an ID, victim authenticates, attacker rides the now-authenticated session → persistent ATO.
• No invalidation on logout — old token still works after /logout → theft window never closes.
• No invalidation on password / email change — a stolen session survives the victim's "I think I was hacked, let me reset" → persistent ATO. This is the single highest-paid session bug class.
• Refresh-token reuse without rotation-detection — a leaked refresh token mints fresh access tokens forever; no reuse-detection means the legitimate user's later refresh does NOT revoke the attacker's branch.
• Predictable / low-entropy session ID — sequential, timestamp- or userId-derived IDs → brute-force or compute other users' sessions.
• JWT-as-session with no exp / no revocation list — stolen JWT = permanent access; logout is cosmetic.

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Grounding — patterns that shaped each phase

No invented CVE/report IDs below. These are the named, publicly-documented patterns this skill encodes:

• Session fixation, login-CSRF, no-regeneration-on-auth — OWASP WSTG-SESS-03 / WSTG-SESS-01; the classic ACROS / Mitja Kolšek session-fixation paper. Highest-impact variant: fixing the session of an SSO/admin user.
• SameSite=Lax sibling-subdomain CSRF reaching session state — Argo CD CVE-2024-22424 (Lax cookies sent on top-level cross-site navigations from a sibling subdomain). Use this when a session cookie relies on SameSite=Lax as its only CSRF defence.
• Refresh-token rotation & automatic reuse-detection — the Auth0/IETF OAuth-Security-BCP model: a rotated refresh token, if replayed, must invalidate the entire token family. Absence = the core bug to prove.
• Device Bound Session Credentials (DBSC) — the W3C/Chrome DBSC draft binds a session to a TPM/device key. Test the downgrade: does the server still accept a non-bound cookie when the DBSC challenge is stripped?
• Cookie attribute hardening — OWASP WSTG-SESS-02; __Host-/__Secure- prefixes per RFC 6265bis. Missing HttpOnly is only a finding when a real XSS/DOM sink exists (chain with hunt-xss/hunt-dom).
• Entropy — NIST SP 800-63B requires ≥64 bits of entropy in a session identifier. Treat anything decodable to a counter/timestamp/userId as a finding regardless of length.

Cross-refs: ATO chaining → hunt-ato; JWT alg/kid tampering → hunt-api-misconfig; OAuth code/state flaws → hunt-oauth; CSRF mechanics → hunt-csrf; cookie-theft sinks → hunt-xss / hunt-dom.

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Attack Surface Signals

Set-Cookie: session=...            # name varies: sid, JSESSIONID, connect.sid,
                                   # PHPSESSID, ASP.NET_SessionId, laravel_session, _csrf
/login /logout /api/login /oauth/token
/auth/refresh /api/token/refresh   # refresh-token rotation surface
/account/change-password /settings/email
?sid= ?session= in URL             # session-in-URL → leaks via Referer/logs (finding)

# Header signals worth flagging immediately:
Set-Cookie: session=abc; Path=/                 # no HttpOnly/Secure/SameSite
Set-Cookie: session=abc; SameSite=None          # None without Secure = rejected by modern browsers, but flag
Set-Cookie: __Host-sess=...; Secure; Path=/     # GOOD — hard to fixate
Sec-Session-Registration: ...                   # DBSC in play → test downgrade

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Step-by-Step Hunting Methodology

Two-session rule. Every invalidation/fixation claim is proven with TWO concrete sessions captured by a real flow — attacker A and victim B — never with hardcoded placeholder strings. Helpers below capture real cookies from curl's Netscape jar.

TARGET=target.com
JAR_A=$(mktemp); JAR_B=$(mktemp)

# Robust session-cookie extractor: handles #HttpOnly_ prefix lines and any
# cookie name (sid/JSESSIONID/connect.sid/PHPSESSID/...). Prints name=value.
get_cookie () {  # $1=jar  $2=name-regex (default: common session names)
  local jar="$1" re="${2:-session|sid|sess|JSESSIONID|connect\.sid|PHPSESSID|laravel_session}"
  awk -v re="$re" '
    /^#HttpOnly_/ { sub(/^#HttpOnly_/,""); }   # strip jar HttpOnly marker
    /^#/ { next }                              # skip remaining comments
    NF>=7 && $6 ~ re { print $6"="$7 }         # field6=name field7=value
  ' "$jar" | tail -1
}

Phase 1 — Session Fixation (regeneration-on-login)

# Step 1: grab a pre-auth session the SERVER hands an anonymous client.
curl -s -L -c "$JAR_A" "https://$TARGET/login" -o /dev/null
PRE=$(get_cookie "$JAR_A"); echo "pre-auth: $PRE"

# Step 1b (stronger): can we FORCE an arbitrary ID? attacker-chosen value.
FIX="session=AAAAdeadbeefAAAA"

# Step 2: authenticate while CARRYING the pre-auth/forced cookie (reuse same jar).
curl -s -L -c "$JAR_A" -b "$JAR_A" -X POST "https://$TARGET/login" \
  -d "username=attacker@example.com&password=CorrectHorse1" -o /dev/null
POST=$(get_cookie "$JAR_A"); echo "post-auth: $POST"

# DECISION:
#  - If $POST == $PRE (value unchanged across the auth boundary) AND that value
#    now returns authenticated data → FIXATION. The server reused the anon ID.
#  - If the forced $FIX value is accepted and authenticates → CRITICAL fixation
#    (attacker controls the ID; no email/XSS needed to plant it).
AUTH=$(curl -s -L -b "$JAR_A" "https://$TARGET/api/me")
echo "$AUTH" | head -c 200

FP guard: a value change is not automatically safe — some apps rotate the readable cookie but keep a stable server-side session keyed by a second cookie. Diff the FULL Set-Cookie set and confirm the old value is genuinely dead (Phase 2). Also confirm /api/me returns your identity, not a generic 200/landing page.

Phase 2 — Invalidation on Logout

# A logs in for real (fresh jar), capture A's live session.
curl -s -L -c "$JAR_A" -X POST "https://$TARGET/api/login" \
  -H 'Content-Type: application/json' \
  -d '{"email":"attacker@example.com","password":"CorrectHorse1"}' -o /dev/null
A=$(get_cookie "$JAR_A"); echo "A=$A"

# Baseline: what does an authenticated /api/me look like for A? (capture body, not just code)
BEFORE=$(curl -s -L -b "$JAR_A" "https://$TARGET/api/me")

# Logout A.
curl -s -L -b "$JAR_A" -X POST "https://$TARGET/api/logout" -o /dev/null

# Replay A's OLD cookie value explicitly (do NOT reuse the jar — logout may have
# overwritten it). Compare body + code against the authenticated baseline.
AFTER=$(curl -s -L -H "Cookie: $A" "https://$TARGET/api/me" -w '\n[%{http_code}]')
echo "AFTER: $AFTER"

FP discipline (mandatory):

• Don't trust the status code. A cached/edge 200 or a generic SPA shell returns 200 for everyone. Body-diff AFTER against BEFORE — the finding is only real if AFTER still contains A's unique identity marker (email, user-id, CSRF token, account name).
• Confirm with a negative control: a random/garbage cookie value must NOT return the same authenticated body. If garbage also yields 200 with user data, the endpoint isn't session-gated and there's no finding here.
• Re-test after a short delay and from a different IP — some servers lazily expire on next access or pin sessions to IP.

Phase 3 — Invalidation on Password / Email Change (persistent-ATO core)

# This is the real two-session flow. A = attacker holding a stolen/old session.
# B = the victim who changes their password believing it revokes access.
# (In a real engagement A is a session you legitimately captured for a TEST account
#  that you also control as B — never use a real third party.)

# 1) Log the TEST account in as session A, capture it.
curl -s -L -c "$JAR_A" -X POST "https://$TARGET/api/login" \
  -H 'Content-Type: application/json' \
  -d '{"email":"victim@example.com","password":"OldPass!1"}' -o /dev/null
SESSION_A=$(get_cookie "$JAR_A"); echo "SESSION_A=$SESSION_A"
BEFORE=$(curl -s -L -H "Cookie: $SESSION_A" "https://$TARGET/api/profile")

# 2) Log the SAME account in as session B (separate jar = "the victim's browser").
curl -s -L -c "$JAR_B" -X POST "https://$TARGET/api/login" \
  -H 'Content-Type: application/json' \
  -d '{"email":"victim@example.com","password":"OldPass!1"}' -o /dev/null

# 3) Victim (session B) changes the password.
curl -s -L -b "$JAR_B" -X POST "https://$TARGET/api/change-password" \
  -H 'Content-Type: application/json' \
  -d '{"old_password":"OldPass!1","new_password":"BrandNew!2"}' -o /dev/null

# 4) THE TEST: replay the OLD SESSION_A captured in step 1.
AFTER=$(curl -s -L -H "Cookie: $SESSION_A" "https://$TARGET/api/profile" -w '\n[%{http_code}]')
echo "AFTER pw-change: $AFTER"

Decision + FP discipline:

• Finding is confirmed only if AFTER returns 200 and the body still carries the account's unique data (body-diff vs BEFORE). A bare 200 on a public/SPA route is not proof.
• Run the garbage-cookie negative control again to prove the endpoint is session-gated.
• Repeat the identical flow for email-change (/settings/email) and for logout-all-devices — apps frequently invalidate the acting session (B) but not sibling sessions (A). That sibling-survival is the exact persistent-ATO primitive hunt-ato chains.
• Severity gate: if the change-password endpoint also lacks a current-password / MFA step-up (per hunt-mfa-bypass), A can pivot from read-only to full takeover → escalate.

Phase 4 — Cookie Attribute Analysis