SUDO_KILLER Gain Root Using Privilege Escalation Various Methods

#sudo exploitation #Abusing sudo #Exploiting Sudo #Linux Privilege Escalation #OSCP

Linux Privilege Escalation through SUDO abuse

INTRO

**WARNING: SUDO_KILLER is part of the KILLER project. SUDO_KILLER is still under development and there might be some issues, please create an issue if you found any. **

Other tool will be added to the KILLER project in the coming months so stay tuned up. Also ideas, bug reports, contributions are more than welcome !

** Stay tuned : Follow me on twitter @ https://twitter.com/TH3xACE **

SUDO_KILLER is a tool that can be used for privilege escalation on linux environment by abusing SUDO in several ways. The tool helps to identify misconfiguration within sudo rules, vulnerability within the version of sudo being used (CVEs and vulns) and the use of dangerous binary, all of these could be abused to elevate privilege to ROOT.

SUDO_KILLER will then provide a list of commands or local exploits which could be exploited to elevate privilege. It is worth noting that the tool does not perform any exploitation on your behalf, the exploitation will need to be performed manually and this is intended.

Features

Some of the checks/functionalities that are performed by the tool.

Misconfigurations
Dangerous Binaries
Vulnerable versions of sudo – CVEs
Dangerous Environment Variables
Credential Harvesting
Writable directories where scripts reside
Binaries that might be replaced
Identify missing scripts

What version 2 of SK includes:

New checks and/or scenarios
1. CVE-2019-14287 – runas
2. No CVE yet – sudoedit – absolute path
3. CVE-2019-18634 – pwfeedback
4. User Impersonation
5. list of users in sudo group
Performance improved
Bugs corrected (checks, export, report,…)
Continous improvement of the way output presented
New videos will be added soon
Annonying password input several time removed
New functionality: offline mode – ability to extract the required info from audited system and run SK on host.
Testing environment : A docker to play with the tool and different scenarios, you can also train on PE.

Usage

Example Online mode

./sudo_killer.sh -c -e -r report.txt -p /tmp

Example Offline mode

Run extract.sh on system to be audited/victim machine. Copy the output from /tmp/sk_offline.txt on the system to be audited/victim machine to your host.

Note: Three checks are missing in the offline mode, still in dev… coming soon…

Run SK with the below parameter:

./sudo_killer.sh -c -i /path/sk_offline.txt

Optional arguments

-c : include CVE checks with respect to sudo version
-i : import (offline mode) from extract.sh
-e : include export of sudo rules / sudoers file
-r : report name (save the output)
-p : path where to save export and report
-s : supply user password for sudo checks (not recommended ++except for CTF)
-h : help

It is worth noting that when using the -c argument, the CVEs identified are only based on the sudo version in used. Very often, a sudo version might be vulnerable but specific condition must be met for exploitation.

SK also check if some conditions are met for several CVEs without the -c such as CVE-2014-0106, CVE-2015-5602, CVE-2017-1000367, CVE-2019-14287 and CVE-2019-18634.

CVEs check

To update the CVE database : run the following script ./cve_update.sh

Providing password (Important)

If you need to input a password to run sudo -l then the script will not work if you don’t provide a password with the argument -s.

How to run SK on the targetted/audited machine

If you are on a machine that has internet connection, just git clone the tool and run it. If you are on a machine that does not have internet, then git clone on your host, compress the tool (tar) then transfert the compressed file via http/smb (apache web server / python simplehttpserver / smb server / nc) then uncompressed the file on the targeted system and enjoy!

Notes

**NOTE : sudo_killer does not exploit automatically by itself, it was designed like this on purpose but check for misconguration and vulnerabilities and then propose you the following (if you are lucky the route to root is near!) :

a list of commands to exploit
a list of exploits
some description on how and why the attack could be performed

Why is it possible to run “sudo -l” without a password?

By default, if the NOPASSWD tag is applied to any of the entries for a user on a host, he or she will be able to run “sudo -l” without a password. This behavior may be overridden via the verifypw and listpw options.

However, these rules only affect the current user, so if user impersonation is possible (using su) sudo -l should be launched from this user as well.

Sometimes the file /etc/sudoers can be read even if sudo -l is not accessible without password.

Docker – Vulnerable testing environment

**IMPORTANT: The recommended way to test the tool is to use the docker image created on purpose for the testing. The image contained several vulnerabilities and misconfigurations related to the usage of SUDO.

Everything is tested from the Docker container available on Docker Hub !**

A Docker image is available on Docker Hub and automatically re-built at each update: https://hub.docker.com/r/th3xace/sudo_killer_demo . It is initially based on official debian:jessie Docker image (debian:jessie).

Pull SUDO_KILLER_DEMO Docker Image from the docker hub : service docker start docker pull th3xace/sudo_killer_demo docker run –rm -it th3xace/sudo_killer_demo
Build locally from Dockerfile (This version maybe a bit more up-to-date): service docker start git clone https://github.com/TH3xACE/SUDO_KILLER.git cd SUDO_KILLER docker build -t th3xace/sudo_killer_demo . docker run –rm -it th3xace/sudo_killer_demo

Note: It is important to note that the docker is just an environment that can be used to play with the tool since it contains several vulns to exploit. The tool is meant to be used on its own.

Demos

Several videos are provided below with different scenarios of exploitation.

The playlist url: https://www.youtube.com/watch?v=Q8iO9mYrfv8&list=PLQPKPAuCA40FMpMKWZLxQydLe7rPL5bml

Coming functionality and improvement

Credentials harvesting – done
Improve the way information on potential vuln and exploit are presented – done
Adding scenario + detection exploit for CVE-2019-14287 – done
Ability to extract data and do analysis offline – on your machine – partially done
Sudo token abuse – done
Dealing with aliases
Extracting sudo rules remotely via SSH (fully automated)
Blind SUDO – This is a new sub-project (whenever you need a password to run sudo -l but you don’t have it)
Audit mode (need to have read access to /etc/sudoers)
If you want me to add any other one… please submit an issue

Credits

The script was developed by myself with the help of online resources found on github and in the wild. Credits also to the authors of the exploits related to CVEs. The authors information and links can be found in the exploit and in the notes provided when running the tool. Special kudos to Vincent Puydoyeux, who gave me the idea to develop this tool and Koutto, for helping me with the docker thing and for improving the tool.

Disclaimer

This script is for Educational purpose ONLY. Do not use it without permission of the owner of the system you are running it. The usual disclaimer applies, especially the fact that me (TH3xACE) is not liable for any damages caused by direct or indirect use of the information or functionality provided by these programs. The author or any Internet provider bears NO responsibility for content or misuse of these programs or any derivatives thereof. By using these programs you accept the fact that any damage (dataloss, system crash, system compromise, etc.) caused by the use of the script is not my responsibility.

Download: https://github.com/TH3xACE/SUDO_KILLER

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Video 1 : Docker – Setup vuln environment	Video 8: Scenario 7 – Environment Variable
Video 2 : Scenario 1 – CVE exploitation	Video 9: Scenario 8 – CVE-2019-14287 – runas
Video 3 : Scenario 2 – Dangerous Bins	Video 10: Scenario 9 – sudoedit – absolute path
Video 4 : Scenario 3 – Misconfig (Wildcard)	Video 11: Scenario 10 – User impersonation I [X2]
Video 5 : scenario 4 – Misconfig (Excessive Rights)	Video 12: Scenario 10 – User impersonation II
Video 6 : Scenario 5 – Misconfig (Missing scripts)	Video 13: offline mode
Video 7 : Scenario 6 – Credentials Harvesting	Video ???????