CVE-2021-44731 Explained : Impact and Mitigation

The race condition in snapd's snap-confine binary could allow a local attacker to gain root privileges by executing arbitrary code, leading to privilege escalation.

Understanding CVE-2021-44731

What is CVE-2021-44731?

A race condition in snapd's snap-confine binary allowed a local attacker to escalate privileges by bind-mounting contents inside a snap's private mount namespace, enabling privilege escalation.

The Impact of CVE-2021-44731

This vulnerability could be exploited by a local attacker to gain root privileges through arbitrary code execution, resulting in privilege escalation.

Technical Details of CVE-2021-44731

Vulnerability Description

The race condition existed in snapd 2.54.2 snap-confine binary, allowing an attacker to gain root privileges by bind-mounting contents in a snap's private namespace.

Affected Systems and Versions

Vendor: Canonical Ltd.
Product: snapd
Versions Affected: unspecified, <= 2.54.2

Exploitation Mechanism

The attacker could perform a bind-mount attack inside the snap's private mount namespace, triggering the execution of arbitrary code by snap-confine and leading to privilege escalation.

Mitigation and Prevention

Immediate Steps to Take

Upgrade to snapd versions 2.54.3+18.04, 2.54.3+20.04, or 2.54.3+21.10.1
Monitor for unauthorized privilege escalations
Enforce the principle of least privilege

Long-Term Security Practices

Regularly update snapd and other software components
Conduct security assessments and audits
Implement secure coding practices

Patching and Updates

Apply security patches promptly to ensure that the snapd version is not vulnerable to this race condition and privilege escalation.