2021 Ubuntu Overlayfs LPE
Description
This module exploits a vulnerability in Ubuntu's implementation of overlayfs. The vulnerability is the result of failing to verify the ability of a user to set the attributes in a running executable. Specifically, when Overlayfs sends the set attributes data to the underlying file system via `vfs_setxattr`, it fails to first verify the data by calling `cap_convert_nscap`. This vulnerability was patched by moving the call to `cap_convert_nscap` into the `vfs_setxattr` function that sets the attribute, forcing verification every time the `vfs_setxattr` is called rather than trusting the data was already verified.
Author(s)
- ssd-disclosure
- bwatters-r7
Platform
Linux
Development
Module Options
To display the available options, load the module within the Metasploit console and run the commands 'show options' or 'show advanced':
msf > use exploit/linux/local/cve_2021_3493_overlayfs
msf exploit(cve_2021_3493_overlayfs) > show targets
...targets...
msf exploit(cve_2021_3493_overlayfs) > set TARGET < target-id >
msf exploit(cve_2021_3493_overlayfs) > show options
...show and set options...
msf exploit(cve_2021_3493_overlayfs) > exploit
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