CVE-2021-4154 : Exploit Details and Defense Strategies
Learn about CVE-2021-4154, a use-after-free flaw in the Linux kernel's cgroup v1 parser that could lead to privilege escalation, container breakout, and system denial of service. Find out how to mitigate the vulnerability.
A local attacker with user privileges could exploit a use-after-free flaw in the Linux kernel's cgroup v1 parser, potentially leading to privilege escalation, container breakout, and system denial of service.
Understanding CVE-2021-4154
This CVE involves a vulnerability in the cgroup v1 parser of the Linux kernel that could be exploited by a local attacker to gain escalated privileges and disrupt system operations.
What is CVE-2021-4154?
CVE-2021-4154 is a use-after-free flaw in the cgroup1_parse_param function in kernel/cgroup/cgroup-v1.c, allowing a user with limited privileges to launch a privilege escalation attack by manipulating the fsconfig syscall parameter.
The Impact of CVE-2021-4154
The impact of this vulnerability includes the potential for a local attacker to perform a container breakout, leading to a denial of service on the system. The exploit could result in increased system vulnerability and unauthorized access.
Technical Details of CVE-2021-4154
This section provides detailed technical information about the vulnerability, including its description, affected systems and versions, and the exploitation mechanism.
Vulnerability Description
The vulnerability arises from a use-after-free flaw in the cgroup1_parse_param function, enabling unauthorized users to exploit the fsconfig syscall parameter for privilege escalation.
Affected Systems and Versions
The vulnerability impacts the Linux kernel and is specifically present in cgroup-v1.c. It has been identified in versions prior to kernel 5.14 rc2.
Exploitation Mechanism
By manipulating the fsconfig syscall parameter, a local attacker could trigger the use-after-free flaw, enabling them to escalate their privileges and potentially break out of container restrictions.
Mitigation and Prevention
In response to CVE-2021-4154, it is crucial to implement immediate steps to mitigate the risks posed by this vulnerability and establish long-term security practices to safeguard against similar issues.
Immediate Steps to Take
Users are advised to monitor security bulletins and apply patches promptly to address the vulnerability. Additionally, considering container security best practices can help prevent unauthorized privilege escalation.
Long-Term Security Practices
Establishing robust access controls, implementing regular security audits, and staying informed about security advisories are essential long-term security practices to enhance system resilience against potential threats.
Patching and Updates
Stay informed about kernel updates and security patches released by Linux distributions. Applying these patches in a timely manner can help address known vulnerabilities and strengthen system security.