module

vmwgfx Driver File Descriptor Handling Priv Esc

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Disclosed
Jan 28, 2022
Created
Feb 1, 2023

Description

If the vmwgfx driver fails to copy the 'fence_rep' object to userland, it tries to
recover by deallocating the (already populated) file descriptor. This is
wrong, as the fd gets released via put_unused_fd() which shouldn't be used,
as the fd table slot was already populated via the previous call to
fd_install(). This leaves userland with a valid fd table entry pointing to
a free'd 'file' object.

We use this bug to overwrite a SUID binary with our payload and gain root.
Linux kernel 4.14-rc1 - 5.17-rc1 are vulnerable.

Successfully tested against Ubuntu 22.04.01 with kernel 5.13.12-051312-generic.

Authors

h00die
Mathias Krause

Platform

Linux

Architectures

x86, x64

References

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/vmwgfx_fd_priv_esc
    msf exploit(vmwgfx_fd_priv_esc) > show targets
        ...targets...
    msf exploit(vmwgfx_fd_priv_esc) > set TARGET < target-id >
    msf exploit(vmwgfx_fd_priv_esc) > show options
        ...show and set options...
    msf exploit(vmwgfx_fd_priv_esc) > exploit
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