PoC Exploit Releases for CVE-2023-52447: A Linux Kernel Flaw Enabling Container Escape
Recently, researchers have published technical details and a proof-of-concept (PoC) exploit for a vulnerability in the Linux kernel, designated as CVE-2023-52447. With a CVSS score of 7.8, this use-after-free vulnerability affects Linux kernel versions from v5.8 to v6.6 and could have serious implications for systems that rely on containerization for security isolation.
At its core, CVE-2023-52447 is a use-after-free flaw in the Linux kernel’s BPF subsystem, specifically related to how arraymap pointers are managed in BPF programs. BPF is a powerful framework that allows users to run custom programs within the kernel, often used for network packet filtering, performance monitoring, and security applications. However, in this case, the vulnerability arises from improper reference counting in certain BPF programs.
The issue occurs when a BPF program holds an arraymap pointer from an array_of_maps without properly increasing the reference count. If the BPF program performs a time-consuming operation, it can allow another thread to free the arraymap and reclaim the memory, leading to a use-after-free condition.
The vulnerability can be exploited by carefully orchestrating a race condition between two threads:
- Modified victim arraymap’s max_entries and index_mask.
- Use victim arraymap to modified near array_of_maps’s value index 0 arraymap as (core_pattern-struct_bpf_array_offset).
- Update array_of_maps to modify core_pattern.
- Achieve container escape.
The security researcher has made the proof-of-concept (PoC) exploit available on GitHub, allowing security teams to better understand the CVE-2023-52447 vulnerability and how it can be exploited. While this PoC is an important resource for defensive measures, it also means that malicious actors have access to the exploit code, increasing the urgency for patching and mitigation.
Fortunately, the vulnerability has been addressed in a recent kernel patch. The issue was fixed via a commit to the Linux kernel, and organizations are strongly encouraged to update to the latest kernel versions that include this patch.
