JS-Tap

JS-Tap is a JavaScript payload for red teamers to attack web applications. It can be used as an XSS payload or post-exploitation implant to capture sensitive data like cookies, local storage, keyboard inputs, and application screenshots. By instrumenting client-side code heavily JS-Tap allows to monitor and exfiltrate data from targeted web applications.

Key Insights

JS-Tap injects itself into the web application’s client-side environment. Once deployed it monitors user interactions and captures data like cookies, local storage, and keystrokes. This data is then sent back to the attacker to gather user behavior and potential application weaknesses.

Modes

JS-Tap has two operation modes: trap mode and implant mode. Trap mode is used as an XSS payload, and JS-Tap creates a full-page iframe and redirects the user within the application. Implant mode is used when the payload is directly added to the targeted application and no iframe is needed.

Command and Control

The payload includes a command and control (C2) system to execute custom JavaScript payloads on compromised clients. This allows us to interact dynamically with the infected environment and gather data based on the attacker’s goals.

Known Variants

No known variants. The tool is modular and customizable so the attacker can adapt it to the target and goal.

Mitigation Strategies

Implement Content Security Policy (CSP) headers to block unwanted scripts.
Audit and sanitize user inputs to prevent XSS.
Use security tools to detect and block malicious JavaScript.
Perform thorough security testing to find and fix client-side vulnerabilities.

Targeted Industries or Sectors

JS-Tap is used by security professionals and attackers to test and exploit web applications. It’s not targeting specific industries or sectors but can be used to any web application with client-side vulnerabilities.

Associated Threat Actors

No threat actors have been publicly known to use JS-Tap. The tool is available on open-source platforms so it’s accessible to everyone, security researchers and potential malicious actors.