CVE-2021-41139 : Exploit Details and Defense Strategies

Anuko Time Tracker is an open-source PHP web-based time tracking application. Versions prior to 1.19.30.5600 are vulnerable to a reflected XSS issue in the time.php file, allowing attackers to execute malicious JavaScript on a user's browser.

Understanding CVE-2021-41139

Anuko Time Tracker prior to version 1.19.30.5600 is susceptible to a reflected XSS vulnerability that enables the execution of attacker-supplied JavaScript in a user's browser through crafted URI links.

What is CVE-2021-41139?

In Anuko Time Tracker versions prior to 1.19.30.5600, a lack of input validation in the date parameter of the URI allows for the injection of malicious scripts, leading to potential XSS attacks.

The Impact of CVE-2021-41139

The vulnerability has a high severity score of 8.1 on the CVSS scale, with high impacts on confidentiality and integrity. It requires user interaction to exploit and poses a risk of executing arbitrary JavaScript in the context of the user's session.

Technical Details of CVE-2021-41139

Anuko Time Tracker's vulnerability to reflected XSS in the time.php file exposes systems to various risks.

Vulnerability Description

The issue arises from the lack of input sanitization in the date parameter of the URI, allowing malicious JavaScript to be executed in a user's browser via crafted links.

Affected Systems and Versions

Product: timetracker
Vendor: Anuko
Versions Affected: < 1.19.30.5600

Exploitation Mechanism

An attacker can exploit this vulnerability by crafting a URI with malicious JavaScript and convincing a logged-on user to click on the link. Once clicked, the attacker-supplied JavaScript executes in the user's browser.

Mitigation and Prevention

Taking immediate steps and implementing long-term security practices are crucial to mitigate the risks associated with CVE-2021-41139.

Immediate Steps to Take

Update to version 1.19.30.5600, where the vulnerability is patched.
Introduce

ttValidDbDateFormatDate

function as in the latest version.
Add a call to the function within the access checks block in time.php.

Long-Term Security Practices

Educate users on the risks of clicking on unknown or suspicious links.
Implement secure coding practices to sanitize and validate user inputs.

Patching and Updates

Regularly update the Anuko Time Tracker application to the latest version to ensure the security patches are in place.