CVE-2021-4001 Explained : Impact and Mitigation
Learn about the CVE-2021-4001 race condition in the Linux kernel's ebpf verifier, allowing local privileged users to manipulate the frozen mapped address space. Find insights on impact, affected versions, mitigation steps, and prevention measures.
A race condition in the Linux kernel's ebpf verifier has been identified, allowing a local user with special privileges to manipulate the frozen mapped address space. This vulnerability impacts kernel versions before 5.16 rc2.
Understanding CVE-2021-4001
This section provides an overview of the CVE-2021-4001 vulnerability.
What is CVE-2021-4001?
The CVE-2021-4001 vulnerability is a race condition within the Linux kernel's ebpf verifier that enables a privileged local user to modify the frozen mapped address space.
The Impact of CVE-2021-4001
The impact of CVE-2021-4001 includes the potential for unauthorized manipulation of kernel memory by users with specific privileges, which could lead to security breaches and system compromise.
Technical Details of CVE-2021-4001
Exploring the technical aspects of CVE-2021-4001.
Vulnerability Description
This vulnerability arises from a missing lock in the kernel/bpf/syscall.c, specifically between bpf_map_update_elem and bpf_map_freeze operations, which can be exploited by local users with cap_sys_admin or cap_bpf privileges.
Affected Systems and Versions
The vulnerability affects kernel versions before 5.16 rc2, impacting the kernel's ebpf verifier functionality.
Exploitation Mechanism
The exploitation of this vulnerability involves leveraging the race condition to manipulate the frozen mapped address space, potentially leading to unauthorized modifications.
Mitigation and Prevention
Guidelines for addressing CVE-2021-4001 and enhancing system security.
Immediate Steps to Take
Immediate actions to mitigate the risk associated with CVE-2021-4001 include monitoring for any unauthorized modifications and restricting privileges of users with cap_sys_admin or cap_bpf capabilities.
Long-Term Security Practices
Implementing robust access control policies, regularly updating the kernel to patched versions, and monitoring system logs for suspicious activities are essential long-term security practices.
Patching and Updates
Applying patches released by Linux kernel maintainers and staying up-to-date with security advisories is crucial to addressing CVE-2021-4001 and other potential vulnerabilities.