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
# Pwnkit Exploit Instructions
I did not write this. This is only to document my exection/instruction of exploit use as there are some very intricate and complicated steps to follow.
Files come from the following source:
https://packetstormsecurity.com/files/165739/PolicyKit-1-0.105-31-Privilege-Escalation.html
Additional assistance on execution found here:
https://ine.com/blog/exploiting-pwnkit-cve-20214034
This was tested/executed on OSCP's Blackgate Practice VM:
Ubuntu 20.04
Kernel 5.8.0-63-generic
How to know if vulnerable:
Check for available SUID and make sure `/usr/bin/pkexec` is a SUID binary:
`find / -perm -4000 2>/dev/null`
Check permissions of the binary:
`ls -al /usr/bin/pkexec`
Check pkexec version:
`/usr/bin/pkexec --version`
Vulnerable version found on Blackgate: `pkexec version 0.105`
Make sure compiler is available on the victim machine.
`gcc version`
# Exploit Execution
Copy the files over to the vicitm machine (Makefile, evil-so.c, exploit.c)
And compile using 'make all' command.
Execute './exploit'
Check shell
# Compilation errors
if you get an error stating that `cc: error trying to exec 'cc1': execvp: No such file or directory`.
use `locate cc1' command to find the binaries:
```
locate cc1
/lib/modules/4.15.0-20-generic/kernel/drivers/iio/adc/cc10001_adc.ko
/lib/modules/4.15.0-20-generic/vdso/.build-id/a0/297fe29f8038ef50a10a26c9fcf5249ccc1184.debug
/usr/lib/gcc/x86_64-linux-gnu/7/cc1
/usr/lib/gcc/x86_64-linux-gnu/7/libcc1.so
/usr/lib/gcc/x86_64-linux-gnu/7/plugin/libcc1plugin.so
/usr/lib/gcc/x86_64-linux-gnu/7/plugin/libcc1plugin.so.0
/usr/lib/gcc/x86_64-linux-gnu/7/plugin/libcc1plugin.so.0.0.0
/usr/lib/x86_64-linux-gnu/libcc1.so.0
/usr/lib/x86_64-linux-gnu/libcc1.so.0.0.0
# Then Export the location to Path for reference, try to build again
Jack@oscp:/home/Jack$ export PATH=$PATH:/usr/lib/gcc/x86_64-linux-gnu/7/cc1
```
文件快照
[4.0K] /data/pocs/100a34b65da9d07dd3f23168fec5979dbea03bde
├── [ 186] evil-so.c
├── [ 626] exploit.c
├── [ 147] Makefile
└── [1.9K] README.md
0 directories, 4 files
备注
1. 建议优先通过来源进行访问。
2. 如果因为来源失效或无法访问，请发送邮箱到 f.jinxu#gmail.com 索取本地快照（把 # 换成 @）。
3. 神龙已为您对POC代码进行快照，为了长期维护，请考虑为本地POC付费，感谢您的支持。