đŸ–„ïžOverlayFS: CVE-2021-3493

Exploit a 2021 Kernel vulnerability in Ubuntu to become root almost instantly!

https://tryhackme.com/room/overlayfs
Room Attributes
Value

Subscription Required

False [Free]

Type

Walkthrough

Difficulty

Info

Tags

PrivEsc, Linux, Ubuntu, Kernel, CVE-2021-3493

Task 1 - What is OverlayFS?

I have a very rough overview of what OverlayFS is

Task 2 - CVE-2021-3493 - OverlayFS Exploit

Deploy the machine with the Start Machine button in this task and wait up to 2 minutes for the VM to boot.

SSH into the machine with the credentials provided in the task text.

Grab the source code for the exploit from SSD-Disclosure here and save it as exploit.c on the target machine.

Compile the exploit with gcc. If you're finding this difficult, a command is given in the hints.

Run your compiled exploit, and get root! What's the flag in /root/?

Reveal Flag đŸš©

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Task 3 - Further reading

Hope you've enjoyed this short room.

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