CVE-2021-3493 PoC — Linux kernel 安全漏洞

Source

https://github.com/inspiringz/CVE-2021-3493

Associated Vulnerability

Title:Linux kernel 安全漏洞 (CVE-2021-3493)
Description:The overlayfs implementation in the linux kernel did not properly validate with respect to user namespaces the setting of file capabilities on files in an underlying file system. Due to the combination of unprivileged user namespaces along with a patch carried in the Ubuntu kernel to allow unprivileged overlay mounts, an attacker could use this to gain elevated privileges.

Description

CVE-2021-3493 Ubuntu OverlayFS Local Privesc (Interactive Bash Shell & Execute Command Entered)

Readme

# CVE-2021-3493

![sample](images/sample.png)

Ubuntu OverlayFS Local Privesc

## Description

"Ubuntu specific issue in the overlayfs file system in the Linux kernel where it did not properly validate the application of file system capabilities with respect to user namespaces. A local attacker could use this to gain elevated privileges, due to a patch carried in Ubuntu to allow unprivileged overlayfs mounts." [- Ubuntu Security](https://ubuntu.com/security/CVE-2021-3493)

> Fixed in Linux 5.11

## Affected Versions

- Ubuntu 20.10
- Ubuntu 20.04 LTS
- Ubuntu 19.04 LTS
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS
- Ubuntu 14.04 ESM

> checklist: https://ubuntu.com/security/CVE-2021-3493

## Usage

- ```gcc exploit.c -o exploit```
- ```chmod +x exploit```
- ```./exploit shell|command```


## References

- https://github.com/briskets/CVE-2021-3493

File Snapshot

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