CVE-2020-14311 Explained : Impact and Mitigation
Learn about the symlink handling vulnerability in Grub2 before version 2.06, allowing a heap-based buffer overflow. Understand the impact, affected systems, exploitation, and mitigation steps.
A vulnerability in Grub2 before version 2.06 could allow an attacker to trigger a heap-based buffer overflow by exploiting a symlink issue on ext filesystems.
Understanding CVE-2020-14311
Grub2, a popular bootloader, is susceptible to a specific symlink-related vulnerability that could lead to a heap-based buffer overflow.
What is CVE-2020-14311?
The vulnerability in Grub2 arises when handling symlinks on ext filesystems. By creating a symbolic link with an inode size of UINT32_MAX, an attacker can cause an arithmetic overflow, resulting in a zero-sized memory allocation and subsequent heap-based buffer overflow.
The Impact of CVE-2020-14311
The impact of this vulnerability is rated as MEDIUM severity with a CVSS base score of 5.7. The attack complexity is considered HIGH, with a LOCAL attack vector and HIGH availability impact. While there is no confidentiality impact, the integrity impact is HIGH, and HIGH privileges are required for exploitation.
Technical Details of CVE-2020-14311
Grub2's vulnerability can be further understood through its technical aspects.
Vulnerability Description
The issue in Grub2 before version 2.06 stems from handling symlinks on ext filesystems, leading to a heap-based buffer overflow.
Affected Systems and Versions
- Product: Grub2
- Vendor: The Grub2 Project
- Vulnerable Version: 2.06
Exploitation Mechanism
The vulnerability can be exploited by creating a symbolic link with specific characteristics on ext filesystems, triggering a chain of events that result in a heap-based buffer overflow.
Mitigation and Prevention
Protecting systems from CVE-2020-14311 requires immediate actions and long-term security practices.
Immediate Steps to Take
- Update Grub2 to version 2.06 or later to mitigate the vulnerability.
- Monitor for any unusual system behavior that could indicate exploitation attempts.
Long-Term Security Practices
- Regularly update and patch all software components to prevent known vulnerabilities.
- Implement strong access controls and least privilege principles to limit the impact of potential attacks.
- Conduct security assessments and audits to identify and address any security gaps.
Patching and Updates
- Apply patches provided by the vendor promptly to address the vulnerability in Grub2.