# LFI2RCE via PHP\_SESSION\_UPLOAD\_PROGRESS

<details>

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### Basic Info

If you found a **Local File Inclusion** even if you **don't have a session** and `session.auto_start` is `Off`. If **`session.upload_progress.enabled`** is **`On`** and you provide the **`PHP_SESSION_UPLOAD_PROGRESS`** in **multipart POST** data, PHP will **enable the session for you**.

```bash
$ curl http://127.0.0.1/ -H 'Cookie: PHPSESSID=iamorange'
$ ls -a /var/lib/php/sessions/
. ..
$ curl http://127.0.0.1/ -H 'Cookie: PHPSESSID=iamorange' -d 'PHP_SESSION_UPLOAD_PROGRESS=blahblahblah'
$ ls -a /var/lib/php/sessions/
. ..
$ curl http://127.0.0.1/ -H 'Cookie: PHPSESSID=iamorange' -F 'PHP_SESSION_UPLOAD_PROGRESS=blahblahblah'  -F 'file=@/etc/passwd'
$ ls -a /var/lib/php/sessions/
. .. sess_iamorange

In the last example the session will contain the string blahblahblah
```

Note that with **`PHP_SESSION_UPLOAD_PROGRESS`** you can **control data inside the session**, so if you includes your session file you can include a part you control (a php shellcode for example).

{% hint style="info" %}
Although most tutorials on the Internet recommends you to set `session.upload_progress.cleanup` to `Off` for debugging purpose. The default `session.upload_progress.cleanup` in PHP is still `On`. It means your upload progress in the session will be cleaned as soon as possible. So this will be **Race Condition**.
{% endhint %}

### The CTF

In the [**original CTF**](https://blog.orange.tw/2018/10/) where this technique is commented, it wasn't enough to exploit the Race Condition but the content loaded needed to start also with the string `@<?php`.

Due to the default setting of `session.upload_progress.prefix`, our **SESSION file will start with a annoying prefix** `upload_progress_` Such as: `upload_progress_controlledcontentbyattacker`

The trick to **remove the initial prefix** was to **base64encode the payload 3 times** and then decode it via `convert.base64-decode` filters, this is because when **base64 decoding PHP will remove the weird characters**, so after 3 times **only** the **payload** **sent** by the attacker will **remain** (and then the attacker can control the initial part).

More information in the original writeup <https://blog.orange.tw/2018/10/> and final exploit <https://github.com/orangetw/My-CTF-Web-Challenges/blob/master/hitcon-ctf-2018/one-line-php-challenge/exp_for_php.py>\
Another writeup in <https://spyclub.tech/2018/12/21/one-line-and-return-of-one-line-php-writeup/>

<details>

<summary><a href="https://www.twitch.tv/hacktricks_live/schedule"><strong>🎙️ HackTricks LIVE Twitch</strong></a> <strong>Wednesdays 5.30pm (UTC) 🎙️ -</strong> <a href="https://www.youtube.com/@hacktricks_LIVE"><strong>🎥 Youtube 🎥</strong></a></summary>

* Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
* Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
* Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
* **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
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</details>


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