Definition
In computing, a sink, or data sink generally refers to the destination of data flow
The word sink has multiple uses in computing:
- In software engineering, an event sink is a class or function that receives events from another object or function
- In cyber security, a sink function is a target function, maybe a vulnerable one, that receives an user's input and does not check it properly
Example
function writeToDOM() { // sink function
const search = document.getElementById('search').value;
const results = document.getElementById('results');
results.innerHTML = 'You searched for: ' + search;
}In the context of web application security, sink functions often make use of the following methods:
document.write()innerHTML()eval()
Use cases
- concolic execution or symbolic execution are often used to automatically create new inputs that can unlock new execution paths, enlarging the code coverage. The more the code is explorable, the easier is to analyze it and to find sink functions