CVE-2018-20852 : Vulnerability Insights and Analysis

In Python versions before 3.7.3, a vulnerability exists in the validation of domains in the http.cookiejar.DefaultPolicy.domain_return_ok function. This flaw could allow an attacker to expose existing cookies to a malicious server by setting up a hostname with another valid hostname as a suffix.

Understanding CVE-2018-20852

This CVE pertains to a security issue in Python versions prior to 3.7.3 that could lead to the exposure of cookies to unauthorized servers.

What is CVE-2018-20852?

The vulnerability arises from incorrect domain validation in Python's http.cookiejar module, potentially enabling attackers to access existing cookies.

The Impact of CVE-2018-20852

The vulnerability could be exploited by malicious actors to steal cookies from legitimate servers, compromising user data and privacy.

Technical Details of CVE-2018-20852

This section provides a deeper insight into the technical aspects of the CVE.

Vulnerability Description

The issue lies in the http.cookiejar.DefaultPolicy.domain_return_ok function, allowing for the leakage of cookies to unauthorized servers.

Affected Systems and Versions

Versions 2.x through 2.7.16, 3.x before 3.4.10, 3.5.x before 3.5.7, 3.6.x before 3.6.9, and 3.7.x before 3.7.3 are impacted by this vulnerability.

Exploitation Mechanism

Attackers can exploit this vulnerability by creating a server with a deceptive hostname to trick programs using http.cookiejar.DefaultPolicy into sending cookies to the wrong server.

Mitigation and Prevention

Protecting systems from CVE-2018-20852 requires immediate actions and long-term security practices.

Immediate Steps to Take

Update Python to version 3.7.3 or newer to mitigate the vulnerability.
Avoid connecting to untrusted servers using programs that utilize http.cookiejar.DefaultPolicy.

Long-Term Security Practices

Regularly update Python and other software to the latest versions to patch security flaws.
Implement network monitoring and intrusion detection systems to detect unauthorized access attempts.

Patching and Updates

Stay informed about security advisories and apply patches promptly to address known vulnerabilities.