CVE-2020-15708

What it actually does

Local attacker with access to the host can connect to the world-readable and writable libvirt control socket, allowing arbitrary file writes or code execution within the context of the libvirt process.

Why it matters to the business

Attackers on the same system can gain elevated access, tamper with virtualization configurations, or disrupt virtual machines, leading to downtime, data integrity issues, and potential full host compromise on affected Ubuntu systems.

How an attack unfolds

An attacker with local shell access locates the overly permissive libvirt control socket created by the packaging, connects directly to it, and issues commands that leverage the socket's privileges to overwrite files or inject and execute code.

How to fix it

Upgrade to a corrected libvirt packaging for Ubuntu 20.04 LTS or later releases that enforces proper socket permissions; verify and correct ownership and mode on the control socket if manual mitigation is required.

How to confirm the fix worked

Confirm the control socket permissions are no longer world-readable and writable (mode 660 or stricter, owned by root:libvirt), and test that non-privileged users cannot connect or issue commands.

Typical attack path

1. Obtain local user access on an affected Ubuntu 20.04 host
2. Locate the world-writable libvirt control socket
3. Connect to the socket using standard tools
4. Issue commands to overwrite arbitrary files or execute code

How to detect it

Review system logs for unexpected connections or commands to the libvirt control socket, and inspect file integrity or recent modifications to virtualization configuration and socket files.

What your security team should do

• Prioritize patching all Ubuntu 20.04 systems running libvirt
• Audit socket permissions across virtualization hosts
• Restrict local user access on systems hosting libvirt
• Monitor for unexpected file modifications in virtualization directories