CVE-2020-1045 : What You Need to Know

Microsoft ASP.NET Core Security Feature Bypass Vulnerability

Understanding CVE-2020-1045

A security feature bypass vulnerability in Microsoft ASP.NET Core.

What is CVE-2020-1045?

A vulnerability exists in the way ASP.NET Core parses encoded cookie names, allowing an attacker to set a second cookie with a specially crafted name.

The Impact of CVE-2020-1045

Severity: High
CVSS Score: 7.5
Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: High
Availability: None
Exploit Code Maturity: Proof-of-Concept
Remediation Level: Official Fix
Report Confidence: Confirmed

Technical Details of CVE-2020-1045

A security feature bypass vulnerability in ASP.NET Core cookie parsing.

Vulnerability Description

The cookie parser in ASP.NET Core decodes entire cookie strings, potentially allowing a malicious attacker to set a second cookie with a crafted name.

Affected Systems and Versions

Affected Versions:
ASP.NET Core 2.1: Version 2.0
ASP.NET Core 3.1: Version 3.0

Exploitation Mechanism

Attackers can exploit the vulnerability by manipulating encoded cookie names to bypass security features.

Mitigation and Prevention

Steps to mitigate the CVE-2020-1045 vulnerability:

Immediate Steps to Take

Apply the official security update provided by Microsoft to fix the cookie parser handling.
Monitor for any unusual cookie behavior that might indicate exploitation.

Long-Term Security Practices

Regularly update and patch ASP.NET Core to ensure the latest security fixes are in place.
Educate developers on secure coding practices to prevent similar vulnerabilities.
Implement secure cookie handling mechanisms in applications.

Patching and Updates

Follow Microsoft's official guidance on patching ASP.NET Core to address the security feature bypass vulnerability.