What is Prototype Pollution?
Prototype Pollution is a vulnerability in which an attacker manipulates the prototype of an object. By doing so, they can add or modify existing prototype properties or methods. When these polluted prototypes are then used by the application logic, unintended side effects can occur.
Prototype Pollution Through Analogy
A Quick Dive into Prototypes
The Foundation of Prototype Pollution
Now, imagine if someone with malicious intent could change the city’s blueprint to include a hidden backdoor in every building. This would mean that they could access any building in the city without detection. Similarly, prototype pollution allows a hacker to introduce or modify properties in an object’s prototype.
How Does It Happen?
Back in our city, if the malicious blueprint alteration went unnoticed, every new building constructed would have this hidden backdoor. In a similar vein, once a prototype is polluted, any new object created will inherit the polluted properties, leading to potential data breaches, application crashes, or even remote code execution.
A Real-World Scenario
Imagine a scenario where our city’s residents can suggest new amenities via an online portal. If the portal doesn’t validate suggestions properly, a malicious user might suggest adding a “spy camera” to the blueprint of every building. In the digital world, an application might accept user input to customize user profiles. If this input isn’t properly validated and sanitized, an attacker could exploit this to pollute the prototype and introduce malicious properties or methods.
Mitigating the Risk
- Avoid Directly Modifying Prototypes: Just as you wouldn’t let anyone tamper with the city’s blueprint, don’t allow direct modifications to an object’s prototype.
- Validate and Sanitize User Input: Before accepting any new tree in the public park, ensure it’s not harmful. Similarly, always validate user input and sanitize it to prevent malicious modifications.
- Use Libraries Wisely: Just as our city would trust established construction companies, only use well-maintained libraries that are aware of and defend against such vulnerabilities.
- Regular Audits: Just as our city would conduct regular checks on its infrastructure, periodically audit your codebase for potential vulnerabilities. Tools like
eslint-plugin-securitycan help detect potential prototype pollution points.