Description

A recently identified Linux Netfilter kernel flaw, known as CVE-2023-32233, has the potential to grant root-level privileges and full control of a system to unprivileged local users. Netfilter, a network address translation and packet filtering framework integrated into the Linux kernel, can be managed through utilities like IPtables and UFW. The flaw stems from Netfilter nf_tables' vulnerability to accepting invalid updates in its configuration, which allows for invalid batch requests that can corrupt the subsystem's internal state under certain circumstances. This corruption exposes a use-after-free vulnerability, enabling arbitrary reads and writes in the kernel memory. Security researchers have successfully demonstrated an exploit for CVE-2023-32233 and shared it on the Openwall mailing list. Multiple Linux kernel versions, including the current stable version (v6.3.1), are affected by this vulnerability. It's important to note that the CVE-2023-32233 vulnerability requires local access to a Linux device for exploitation. In response, engineer Pablo Neira Ayuso submitted a commit to the Linux kernel source code that introduces two functions to manage the lifecycle of anonymous sets within the Netfilter nf_tables subsystem. This fix ensures proper handling of anonymous set activation and deactivation, preventing further updates and mitigating memory corruption. By doing so, the fix thwarts attackers from escalating their privileges to root level by preventing the exploitation of the use-after-free issue. Security researchers Piotr Krysiuk and Patryk Sondej discovered the Linux Netfilter kernel flaw and reported it to the Linux kernel team. They have announced that the exploit and detailed exploitation techniques will be publicly disclosed on May 15th, 2023, in compliance with the Linux-distros list policy.