This is a PoC for Nimbuspwn, as originally described in https://www.microsoft.com/security/blog/2022/04/26/microsoft-finds-new-elevation-of-privilege-linux-vulnerability-nimbuspwn/
It runs reliably on Ubuntu Desktop installs, but does not run by default on Ubuntu Server installs. It is possible to configure a server install to be vulnerable, although this is not expected to be a common configuration.
This vulnerability is generally not present in pure systemd-networkd based systems, since in that case, the legitimate systemd-networkd process will be holding the required D-Bus name. However, it is present where attempts have been made to disable systemd-networkd, for example using scripts such as https://gist.github.com/polrus/772618cfead9c1b63b246584024d7765, which enables NetworkManager for Ubuntu Server installs.
sudo apt update
sudo apt -y install network-manager
sudo nano /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg
Add content: "network: {config: disabled}" and save
sudo nano /etc/netplan/50-cloud-init.yaml
Add "renderer: NetworkManager" to "network:" block
sudo netplan generate
sudo netplan apply
sudo systemctl enable NetworkManager.service
sudo systemctl restart NetworkManager.service
sudo systemctl disable systemd-networkd
To aid detection of this specific poc we have released a sigma rule. It should be noted that this sigma rule is specific to our poc code and may not detect all possible exploit attempts.
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