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Executive Summary
CVE-2023-2163 is a critical vulnerability identified in the Linux Kernel, specifically affecting versions 5.4 and above. This vulnerability arises from incorrect verifier pruning in the Berkeley Packet Filter (BPF), leading to unsafe code paths being incorrectly marked as safe. The consequences of this flaw are severe, including arbitrary read/write in kernel memory, lateral privilege escalation, and container escape. Given the widespread use of the Linux Kernel in various sectors, including finance, healthcare, and government, the potential impact of this vulnerability is significant. Immediate action is required to mitigate the risks associated with CVE-2023-2163.
Technical Information
CVE-2023-2163 is a high-severity vulnerability in the Linux Kernel, specifically affecting versions 5.4 and above. The vulnerability is rooted in the Berkeley Packet Filter (BPF), a technology used for packet filtering and network monitoring. The issue arises from incorrect verifier pruning, which leads to unsafe code paths being incorrectly marked as safe. This flaw can be exploited to perform arbitrary read/write operations in kernel memory, escalate privileges laterally within a system, and escape containerized environments.
The vulnerability has been assigned a CVSS v3.1 Base Score of 8.8, indicating its high severity. The vector for this vulnerability is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H, which means it requires local access, low attack complexity, and low privileges to exploit. The impact on confidentiality, integrity, and availability is high.
The root cause of CVE-2023-2163 is a flaw in the BPF verifier, which is responsible for ensuring that BPF programs are safe to execute. Due to incorrect pruning, unsafe code paths are incorrectly marked as safe, allowing attackers to exploit these paths to perform arbitrary read/write operations in kernel memory. This can lead to lateral privilege escalation, where an attacker with limited privileges can gain higher privileges within the system. Additionally, in containerized environments, this vulnerability can be used to escape the container and gain access to the host system.
For a detailed technical analysis, refer to the Google Security Blog: https://bughunters.google.com/blog/6303226026131456/a-deep-dive-into-cve-2023-2163-how-we-found-and-fixed-an-ebpf-linux-kernel-vulnerability
Exploitation in the Wild
CVE-2023-2163 has been actively exploited in the wild, primarily targeting systems running affected versions of the Linux Kernel. Exploits have been observed in various attack scenarios, including lateral privilege escalation, container escape, and arbitrary read/write operations in kernel memory. Indicators of Compromise (IOCs) include unusual read/write operations in kernel memory, unexpected privilege escalations, and container escape attempts.
For more information on observed exploits, refer to the Rapid7 vulnerability database: https://www.rapid7.com/db/vulnerabilities/ubuntu-cve-2023-2163/
APT Groups using this vulnerability
While specific APT groups exploiting CVE-2023-2163 have not been publicly identified, the nature of the vulnerability makes it a valuable target for advanced persistent threats seeking to escalate privileges or escape containerized environments. Given the critical nature of this vulnerability, it is likely that APT groups targeting sectors such as finance, healthcare, and government may leverage this flaw in their attacks.
Affected Product Versions
CVE-2023-2163 affects Linux Kernel versions from 5.4 up to (excluding) 6.3. It is crucial for organizations running these versions to apply the necessary patches to mitigate the risks associated with this vulnerability.
Workaround and Mitigation
To mitigate the risks associated with CVE-2023-2163, it is recommended to update the Linux Kernel to a patched version that addresses this vulnerability. The patch can be found in the official Linux Kernel repository: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=71b547f561247897a0a14f3082730156c0533fed
In addition to updating the kernel, organizations should monitor their systems for Indicators of Compromise (IOCs), such as unusual read/write operations in kernel memory, unexpected privilege escalations, and container escape attempts. Implementing security best practices, such as the principle of least privilege, regular system updates, and continuous monitoring, can also help mitigate the risks associated with this vulnerability.
References
For further details and updates, refer to the following resources:
NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-2163
Google Security Blog: https://bughunters.google.com/blog/6303226026131456/a-deep-dive-into-cve-2023-2163-how-we-found-and-fixed-an-ebpf-linux-kernel-vulnerability
Ubuntu Security: https://ubuntu.com/security/CVE-2023-2163
Rapid7: https://www.rapid7.com/db/vulnerabilities/ubuntu-cve-2023-2163/
Packet Storm: https://packetstormsecurity.com/files/cve/CVE-2023-2163
Google Security Research: https://google.github.io/security-research/pocs/linux/cve-2023-2163/
Rescana is here for you
At Rescana, we understand the critical importance of staying ahead of emerging threats. Our Continuous Threat and Exposure Management (CTEM) platform helps organizations identify, assess, and mitigate vulnerabilities like CVE-2023-2163. By leveraging our advanced threat intelligence and monitoring capabilities, we provide our customers with the tools and insights needed to protect their systems and data. If you have any questions about this report or any other issue, please contact us at ops@rescana.com.
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