CVE-2021-3759 represents a memory overflow vulnerability found in the Linux kernel’s ipc functionality, specifically within the memcg subsystem. This vulnerability arises when a local user calls the semget function multiple times to create semaphores, leading to resource starvation and resulting in denial of service. With a CVSS score of 5.5, this is classified as a medium severity vulnerability, primarily impacting system availability.
The potential risk to organizations includes significant downtime, as attackers may exploit this vulnerability to disrupt system operations. Given its local attack vector, the urgency for defenders to address this vulnerability is moderate, particularly for environments using Debian and Linux kernels.
Organizations should prioritize patching this vulnerability to mitigate any risk of denial of service. Monitoring and auditing of systems should also be conducted to ensure the integrity of the environment.
The vulnerability was published on August 23, 2022. As of now, there is confirmed exploit availability, which adds to the urgency for organizations to implement necessary mitigations.
Vulnerability Details
This vulnerability allows a local user to starve resources through improper handling of semaphore creation, specifically when invoking the semget function. The CVSS vector for this vulnerability is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H, indicating a local attack vector with low complexity and low privileges required, leading to a high impact on availability.
Affected products include the Linux kernel and Debian Linux 10.0. The CWE classifications associated with this vulnerability are CWE-400 (Uncontrolled Resource Consumption) and CWE-770 (Allocation of Resources Without Limits).
Technical Analysis
The root cause of this vulnerability lies in the Linux kernel's memory management when handling the semget function. Attackers with local access can trigger this flaw by creating numerous semaphores, ultimately exhausting system resources. The attack vector is local, with an attack complexity rated as low, allowing relatively unprivileged users to exploit this vulnerability without requiring user interaction.
The implications of this vulnerability extend to significant impacts on the availability of affected systems. Although confidentiality and integrity are not directly impacted, the denial of service could lead to operational disruptions.
Risk & Impact Analysis
Real-world deployment risks associated with CVE-2021-3759 include potential downtime and resource exhaustion leading to operational limitations. Organizations leveraging Debian or Linux environments are particularly at risk due to dependency on the Linux kernel's ipc functionality. The blast radius could be significant, particularly in multi-user systems where local exploitation could be achieved without sophisticated skills.
Given the CVSS score of 5.5, organizations should address this vulnerability in their priority patch cycle. The availability impact is rated as high, necessitating immediate attention to mitigate possible service disruptions.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | Yes |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The vulnerability affects all versions of the Linux kernel prior to the vendor patch. Specifically, Debian Linux 10.0 is confirmed as affected. Organizations should ensure they are on the latest version to mitigate risks.
Mitigation & Remediation
Organizations should prioritize patching this vulnerability by upgrading to the latest version of the Linux kernel and Debian distributions. If immediate patching is not possible, consider implementing configuration hardening by limiting local user access and monitoring for abnormal semaphore usage.
For further assistance in vulnerability management, organizations can leverage vulnerability management programs to ensure ongoing security.
Detection Guidance
To detect potential exploitation of this vulnerability, organizations should monitor logs for excessive semaphore creation requests and investigate any unusual resource consumption patterns. Behavioral anomalies indicating resource starvation should also be flagged for further analysis.
AppSecure Threat Intelligence Insight
CVE-2021-3759 highlights a significant risk in local privilege management within the Linux kernel ecosystem. As local exploitation becomes increasingly prevalent, organizations must remain vigilant and proactive in monitoring and patching vulnerabilities.
This incident emphasizes the importance of continuous security assessments. Organizations should consider implementing regular penetration testing to identify and remediate similar vulnerabilities.
Finally, organizations should stay informed about emerging threats and trends in vulnerability management by reviewing resources such as the Vulnerability Management Program Design to enhance their security posture.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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