CVE-2018-20239 : Exploit Details and Defense Strategies

CVE-2018-20239, published on April 29, 2019, addresses a vulnerability in Atlassian Application Links that could allow remote attackers to inject arbitrary HTML or JavaScript.

Understanding CVE-2018-20239

This CVE identifies a cross-site scripting (XSS) vulnerability in various Atlassian products due to insecure handling of the "applinkStartingUrl" parameter.

What is CVE-2018-20239?

Prior to version 5.0.11, Atlassian Application Links were susceptible to XSS attacks, enabling malicious actors to inject unauthorized code.

The Impact of CVE-2018-20239

The vulnerability could be exploited by remote attackers to execute malicious scripts, potentially leading to unauthorized data access or manipulation.

Technical Details of CVE-2018-20239

Vulnerability Description

The flaw allowed for the injection of arbitrary HTML or JavaScript through the "applinkStartingUrl" parameter, affecting multiple Atlassian products.

Affected Systems and Versions

Atlassian Application Links before 5.0.11
Confluence before 6.15.2
Crucible before 4.7.0
Crowd before 3.4.3
Fisheye before 4.7.0
Jira before 7.13.3 and 8.x before 8.1.0

Exploitation Mechanism

Attackers could exploit the vulnerability by injecting malicious code via the vulnerable parameter, potentially leading to XSS attacks.

Mitigation and Prevention

Immediate Steps to Take

Upgrade Atlassian Application Links to version 5.0.11 or higher.
Apply patches provided by Atlassian for affected products.

Long-Term Security Practices

Regularly monitor and update software for security patches.
Implement input validation mechanisms to prevent XSS vulnerabilities.

Patching and Updates

Ensure all Atlassian products, especially those mentioned, are regularly updated with the latest security patches to mitigate the risk of XSS vulnerabilities.