CVE-2017-8820 : What You Need to Know
Learn about CVE-2017-8820, a vulnerability in Tor versions before 0.2.5.16, 0.2.6 through 0.2.8 before 0.2.8.17, 0.2.9 before 0.2.9.14, 0.3.0 before 0.3.0.13, and 0.3.1 before 0.3.1.9, allowing remote attackers to cause a denial of service.
Tor versions before 0.2.5.16, 0.2.6 through 0.2.8 before 0.2.8.17, 0.2.9 before 0.2.9.14, 0.3.0 before 0.3.0.13, and 0.3.1 before 0.3.1.9 are vulnerable to a security issue that allows remote attackers to cause a denial of service by exploiting a flaw in the way directory authorities handle malformed descriptors.
Understanding CVE-2017-8820
This CVE entry identifies a vulnerability in Tor software versions that could lead to a denial of service attack.
What is CVE-2017-8820?
CVE-2017-8820 is a security vulnerability found in Tor versions prior to 0.2.5.16, 0.2.6 through 0.2.8 before 0.2.8.17, 0.2.9 before 0.2.9.14, 0.3.0 before 0.3.0.13, and 0.3.1 before 0.3.1.9. It allows remote attackers to trigger a denial of service by exploiting a specific flaw in the handling of malformed descriptors by directory authorities.
The Impact of CVE-2017-8820
The vulnerability in CVE-2017-8820 could be exploited by remote attackers to cause a denial of service, potentially leading to service disruption or unavailability.
Technical Details of CVE-2017-8820
CVE-2017-8820 involves the following technical aspects:
Vulnerability Description
The vulnerability in Tor versions before the specified releases allows for a denial of service attack through a flaw in descriptor handling by directory authorities.
Affected Systems and Versions
- Tor before 0.2.5.16
- Tor 0.2.6 through 0.2.8 before 0.2.8.17
- Tor 0.2.9 before 0.2.9.14
- Tor 0.3.0 before 0.3.0.13
- Tor 0.3.1 before 0.3.1.9
Exploitation Mechanism
Remote attackers can exploit this vulnerability by sending specially crafted malformed descriptors to directory authorities, triggering a NULL pointer dereference and causing the application to crash.
Mitigation and Prevention
To address CVE-2017-8820, consider the following mitigation strategies:
Immediate Steps to Take
- Update Tor software to versions 0.2.5.16, 0.2.6 through 0.2.8.17, 0.2.9.14, 0.3.0.13, or 0.3.1.9 to mitigate the vulnerability.
- Monitor for any unusual activity that could indicate a denial of service attack.
Long-Term Security Practices
- Regularly update Tor software to the latest stable releases to ensure protection against known vulnerabilities.
- Implement network monitoring and intrusion detection systems to detect and respond to potential attacks.
Patching and Updates
- Stay informed about security advisories and patches released by Tor Project to address vulnerabilities like CVE-2017-8820.