CVE-2021-4154 represents a significant vulnerability within the Linux kernel that could have serious implications for affected systems. This vulnerability allows local attackers to exploit a use-after-free flaw in the cgroup v1 parser, specifically within the function cgroup1_parse_param located in kernel/cgroup/cgroup-v1.c. Given its CVSS score of 8.8, classified as high severity, the risk to organizations includes potential privilege escalation, leading to container breakouts and denial of service on the system.
The nature of this vulnerability highlights the critical need for timely remediation. As local attackers could exploit this flaw with relatively low complexity and privileges, organizations are urged to prioritize patching this vulnerability immediately. The potential impact on system integrity and availability underscores the urgency of addressing this issue.
Currently, there are known exploitations of this vulnerability, although no public proof of concept (PoC) has been confirmed. This situation emphasizes the need for proactive measures to safeguard systems against potential attacks. Organizations must remain vigilant and implement necessary security measures to mitigate risks associated with this vulnerability.
In summary, organizations using affected versions of the Linux kernel must take immediate action to patch this vulnerability to prevent possible exploitation that could lead to severe consequences.
Vulnerability Details
The official description of CVE-2021-4154 highlights a use-after-free flaw in the cgroup1_parse_param function in the Linux kernel's cgroup v1 parser. This vulnerability can be exploited by a local attacker with user privileges to escalate privileges through the fsconfig syscall parameter. The result could be a container breakout and a denial of service on the system.
With a CVSS score of 8.8, the vulnerability is classified as high severity. The attack vector is local, requiring low attack complexity and only low privileges. There is no user interaction required, and the scope of the impact is considered changed, affecting confidentiality, integrity, and availability significantly.
The vulnerability was published on February 4, 2022, and has been noted under CWE-416 (Use After Free). Organizations utilizing the Linux kernel versions specified in the configurations section are particularly at risk.
Technical Analysis
The root cause of CVE-2021-4154 lies in the mishandling of memory management within the cgroup v1 parser, specifically the cgroup1_parse_param function. Attackers may leverage this flaw by manipulating the fsconfig syscall parameter, leading to a condition where previously freed memory can be accessed again. The attack vector is local, meaning that an attacker must have access to the system where the vulnerable kernel is running.
The attack complexity is low, as the prerequisites for exploitation are minimal, requiring only user-level privileges. No user interaction is necessary for the attack to succeed. The impacts are severe, with significant confidentiality, integrity, and availability consequences for the affected systems.
Risk & Impact Analysis
The real-world deployment risk associated with CVE-2021-4154 is substantial. Organizations utilizing the affected Linux kernel versions are at risk of privilege escalation, which could lead to unauthorized access to sensitive data and functionalities. The potential for container breakout further amplifies this risk, especially in environments relying on containerization for deployment.
As this vulnerability affects critical components of the operating system, the blast radius for an attack leveraging this flaw could be extensive. Organizations must assess their exposure and implement immediate patching as part of their urgent remediation strategy. Given its high severity status, this should be prioritized in the patch cycle.
Signal | Status |
|---|---|
Known Exploit | Yes |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The following versions of the Linux kernel are affected by CVE-2021-4154:
All versions from 5.1 up to, but not including, 5.4.134; from 5.5 up to, but not including, 5.10.52; from 5.11 up to, but not including, 5.12.19; from 5.13 up to, but not including, 5.13.4; and the 5.14:rc1 version are vulnerable. Organizations should ensure they upgrade to the patched versions as they become available.
Mitigation & Remediation
To mitigate the risks associated with CVE-2021-4154, organizations should prioritize patching their affected systems. It is crucial to upgrade the Linux kernel to the latest stable version that includes the fix for this vulnerability.
If an immediate upgrade is not possible, organizations can implement additional security measures such as restricting user access rights, monitoring for unusual activity that may indicate exploitation attempts, and employing network controls to limit exposure.
Continuous penetration testing can help to identify vulnerabilities and ensure that the system remains secure against emerging threats.
Detection Guidance
Organizations should implement logging mechanisms to capture system calls related to the cgroup functionality. Monitoring for behavioral anomalies and unexpected container behaviors can help detect potential exploitation attempts.
Network signatures should also be developed to alert on suspicious activity that could indicate an attempt to exploit this vulnerability. Regular assessments and audits may further assist in identifying any changes in system configurations or unauthorized access.
AppSecure Threat Intelligence Insight
CVE-2021-4154 represents a critical point of concern within the Linux kernel, highlighting the ongoing challenges of maintaining security in complex environments. The pattern of privilege escalation vulnerabilities continues to be a significant threat to organizations.
Security teams should take this as a reminder to regularly review their security posture and implement best practices in vulnerability management. The lessons learned from this incident can guide future defenses against similar vulnerabilities.
Understanding penetration testing methodology can help organizations identify and remediate vulnerabilities effectively.
Moreover, leveraging resources like an established vulnerability management program can provide a structured approach to addressing vulnerabilities proactively.
To further enhance security, organizations should consider engaging in red teaming exercises to simulate real-world attacks and better understand their security weaknesses.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
.webp)