This post describes how to obtain Linux Privilege Escalation through SUDO abuse.
The tool can be used by pentesters, system admins, CTF players, students, System Auditors and trolls :).
**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.
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.
- 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
- New checks and/or scenarios:
- CVE-2019-14287 – runas
- No CVE yet – sudoedit – absolute path
- CVE-2019-18634 – pwfeedback
- User Impersonation
- 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.
./sudo_killer.sh -c -e -r report.txt -p /tmp
- 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
- -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
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!
**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 (This version maybe a bit more up-to-date):
service docker start docker pull th3xace/sudo_killer_demo docker run --rm -it th3xace/sudo_killer_demo
- Build locally from Dockerfile :
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.
Several videos are provided below with different scenarios of exploitation.
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