CVE-2024-50063
Description
A flaw was found in the Linux kernel's Berkeley Packet Filter (BPF) subsystem. A privileged local attacker could exploit this by crafting BPF programs that improperly use "tail calls" to switch between different kernel function hooks. This bypasses critical security checks related to BPF program context or return values, potentially leading to information disclosure or privilege escalation.
Statement
The default Red Hat Enterprise Linux kernel prevents unprivileged users from being able to use eBPF by the kernel.unprivileged_bpf_disabled sysctl. This would require a privileged user with CAP_SYS_ADMIN or root to be able to abuse this flaw reducing its attack space.
For the Red Hat Enterprise Linux 9 to confirm the current state, inspect the sysctl with the command:
cat /proc/sys/kernel/unprivileged_bpf_disabled
The setting of 1 would mean that unprivileged users can not use eBPF, mitigating the flaw.
Mitigation
To mitigate this issue, ensure that unprivileged eBPF usage is disabled. This can be achieved by setting the `kernel.unprivileged_bpf_disabled` sysctl to 1.
To check the current status:
`cat /proc/sys/kernel/unprivileged_bpf_disabled`
To disable unprivileged eBPF usage for the current session:
`echo 1 > /proc/sys/kernel/unprivileged_bpf_disabled`
To make this change persistent across reboots, create a file named `/etc/sysctl.d/99-disable-unprivileged-bpf.conf` with the following content:
`kernel.unprivileged_bpf_disabled = 1`
Then, apply the changes:
`sysctl --system`
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.7 | 7.8 | 7.8 |
| Attack Vector | Local | Local | Local |
| Attack Complexity | Low | Low | Low |
| Privileges Required | High | Low | Low |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | High | High | High |
| Integrity Impact | High | High | High |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Other
Technical Impact: Alter Execution Logic
An attacker could cause the product to skip critical steps or perform them in the wrong order, bypassing its intended business logic. This can sometimes have security implications.
Frequently Asked Questions
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