CVE-2020-10593 : Security Advisory and Response

Tor before 0.3.5.10, 0.4.x before 0.4.1.9, and 0.4.2.x before 0.4.2.7 allows remote attackers to cause a Denial of Service (memory leak), aka TROVE-2020-004. This occurs in circpad_setup_machine_on_circ because a circuit-padding machine can be negotiated twice on the same circuit.

Understanding CVE-2020-10593

This CVE identifies a vulnerability in Tor versions prior to specified releases that can be exploited by remote attackers to trigger a Denial of Service attack due to a memory leak issue.

What is CVE-2020-10593?

CVE-2020-10593 is a vulnerability in Tor versions before 0.3.5.10, 0.4.x before 0.4.1.9, and 0.4.2.x before 0.4.2.7 that allows attackers to cause a Denial of Service by exploiting a memory leak.

The Impact of CVE-2020-10593

The vulnerability can be exploited remotely, potentially leading to a Denial of Service condition on affected systems running the vulnerable Tor versions.

Technical Details of CVE-2020-10593

This section provides more in-depth technical details about the CVE.

Vulnerability Description

The vulnerability in Tor versions before specified releases allows remote attackers to trigger a Denial of Service attack through a memory leak issue in circpad_setup_machine_on_circ.

Affected Systems and Versions

Tor versions before 0.3.5.10
Tor 0.4.x before 0.4.1.9
Tor 0.4.2.x before 0.4.2.7

Exploitation Mechanism

The vulnerability can be exploited remotely by causing a circuit-padding machine to be negotiated twice on the same circuit, resulting in a memory leak and potential Denial of Service.

Mitigation and Prevention

To address CVE-2020-10593, follow these mitigation and prevention strategies:

Immediate Steps to Take

Update Tor to versions 0.3.5.10, 0.4.1.9, or 0.4.2.7 or later to mitigate the vulnerability.
Monitor network traffic for any suspicious activity that could indicate exploitation of the vulnerability.

Long-Term Security Practices

Regularly update and patch Tor and other software to ensure protection against known vulnerabilities.
Implement network segmentation and access controls to limit the impact of potential attacks.

Patching and Updates

Apply patches and updates provided by the Tor project promptly to address security vulnerabilities and enhance system security.