CVE-2021-23240 : What You Need to Know

Sudo before version 1.9.5 is affected by CVE-2021-23240, allowing a local unprivileged user to escalate privileges through symlink attacks. This vulnerability impacts systems with SELinux RBAC support in permissive mode.

Understanding CVE-2021-23240

This section will provide insights into the nature and implications of the CVE-2021-23240 vulnerability.

What is CVE-2021-23240?

The CVE-2021-23240 vulnerability exists in

selinux_edit_copy_tfiles

in

sudoedit

, enabling a local unprivileged user to gain file ownership and escalate privileges by manipulating temporary files with symlinks. Notably, systems without SELinux are not susceptible to this exploit.

The Impact of CVE-2021-23240

The impact of this vulnerability is significant as it allows an attacker to elevate their privileges on the system, potentially leading to further exploitation and compromise of sensitive data.

Technical Details of CVE-2021-23240

In this section, we delve into the technical aspects and specifics of CVE-2021-23240.

Vulnerability Description

The vulnerability in

sudoedit

allows a local unprivileged user to exploit symlink vulnerabilities, ultimately gaining elevated file ownership and escalated privileges on the system.

Affected Systems and Versions

All systems running Sudo versions before 1.9.5 are vulnerable to CVE-2021-23240, particularly those with SELinux RBAC support in permissive mode.

Exploitation Mechanism

By replacing a temporary file with a symlink leading to an arbitrary file target, an unprivileged local user can abuse the vulnerability to gain file ownership and privilege escalation.

Mitigation and Prevention

This section outlines crucial steps to mitigate and prevent exploitation of CVE-2021-23240.

Immediate Steps to Take

Users are advised to upgrade Sudo to version 1.9.5 or higher to patch the vulnerability. Additionally, enforcing least privilege access can limit the impact of potential symlink attacks.

Long-Term Security Practices

Implementing robust file permission settings, regularly monitoring system logs for suspicious activities, and conducting security awareness training can enhance long-term security posture.

Patching and Updates

Regularly applying security patches and updates, especially for critical software components like Sudo, is essential to address known vulnerabilities and protect against exploitation.