What makes inline JavaScript blocks a security risk?

Currently delving into the Chrome extension document titled "Content Security Policy (CSP)", and I came across an interesting piece of information:

The documentation mentions that inline JavaScript, as well as risky string-to-JavaScript techniques like eval, are prohibited from executing. This rule extends to both inline blocks and inline event handlers (such as <button onclick="...">).

...

Furthermore, there isn't a way to relax this restriction against running inline JavaScript. Even setting a script policy that includes unsafe-inline will not have any impact, as it is intentionally implemented this way.

Could someone shed light on why inline <script> blocks are deemed unsafe? Examples would be greatly appreciated if possible.

Many thanks in advance!

javascriptsecurityinline-scripting

Answer №1

According to the information provided:

A key restriction in place helps thwart a significant number of cross-site scripting attacks by eliminating the possibility of inadvertently running scripts from a dubious third-party source.

In essence, any script that is utilized must be stored in a separate file that is locally accessible to the extension. This precautionary measure prevents the loading of third-party scripts that may be injected into your page or included externally like so:

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>

For instance, consider a scenario where there is a form for users to fill out. If a user inputs a script tag with JavaScript embedded within it (such as on a discussion forum), and this input is not properly sanitized before being posted, it could lead to malicious code being executed whenever someone accesses that content. This security feature ensures that such scripts are prevented from executing.

Similar questions

If you have not found the answer to your question or you are interested in this topic, then look at other similar questions below or use the search

The issue with the AngularJS filter seems to be arising specifically when applied to

My AngularJS filter isn't functioning properly when used with an Object. Here's the View: <input type="text" ng-model="searchKeyUser.$" placeholder="Search Keys" class="form-control"><br> <ul class="list-group"> <li cla ...

javascriptarraysangularjsfiltercakephp-2.0

Retrieve the identifiers of various HTML elements and store them in an array

Within a div, there are multiple objects. I am trying to retrieve the IDs of all elements based on their class, knowing that the number of elements may vary. So far, my attempt has been: arr = $(".listitem #checkBox").hasClass('checkedItem').att ...

javascriptjqueryhtml

Utilizing ReactJS useState to eliminate a className

Basically, I'm trying to remove a className from an element when a button is clicked. I've attempted to use useState hooks and a regular function, with the onClick event on the button triggering this function/setUseState. However, the className l ...

javascriptcssreactjsuse-state

Setting values and options in Material UI AutoComplete and then assigning the selected value to an object when onChange event occurs - how can it be

I am working on a project where I have a brand object with the field cat_id. When the page loads, categories are loaded into an autocomplete select. My goal now is to set the value of category id as the value for a category option in the autocomplete, an ...

javascriptreactjsselectautocompletematerial-ui

Top technique for verifying the presence of duplicates within an array of objects

How can I efficiently check for duplicates in typescript within a large array of objects and return true or false based on the results? let testArray: { id: number, name: string }[] = [ { "id": 0, "name": "name1" }, ...

javascriptangulartypescript

Make a POST request using AJAX to the current page and retrieve a value using the $_POST method

I've been trying to solve this puzzle, but I can't seem to figure out what's going wrong... Here's the situation: I'm passing a value to a function and using AJAX to send this value via a POST request to the same page. Upon succes ...

javascriptphpjqueryajaxpost

I am currently working on a website that offers different themes, and I am attempting to update the iframe to reflect the selected theme on the site

I'm feeling lost on how to accomplish this task. Despite my efforts, I have been unable to find a solution so far. Perhaps utilizing javascript might be the key here, yet I am uncertain about integrating it into the existing script that I use for modi ...

javascripthtmlcssiframethemes

Express: using async and await leads to an error when attempting to access "result" before it has been initialized

When using the login function that utilizes ExecuteSQL to validate user existence, an error occurs during file execution related to async await. ReferenceError: Cannot access 'result' before initialization at /Users/naseefali/Documents/Projects ...

javascriptsql-serverapirestexpress

`Can I distribute configuration data to all components using a JavaScript file?`

My approach involves using config data to simultaneously affect the status of all components. I achieve this by importing the config object from the same JavaScript file and incorporating it into each component's data. It appears to work seamlessly, ...

javascriptvue.jsvue-component

PHP captures the checkbox value through the $_POST method, whereas jQuery removes the checked class from it

I currently have a form with 2 checkboxes: Registered and Not Registered. If the Registered checkbox is ticked, then 2 additional options should appear: Active and Not Active. If the Registered checkbox is unticked, both the Active and Not Active options ...

javascriptphpjquerycheckbox

javascriptfunction FindLargerValue(array, targetValue)

Looking for a JavaScript code to work with my function called BiggerOf(array, value). The function is designed to calculate how many elements in the array are bigger than a specific value and then print those elements. Here's an example of what I need ...

javascriptarraysfunction

Removing an item from a list by clicking a button

I am currently developing my own version of a mini Twitter platform. Everything is functioning smoothly, however I am facing an issue with deleting specific tweets upon the click of a button. I have attempted using splice(), but it consistently deletes th ...

javascripthtmlarrayssplice

Navigating an Array in Typescript

Angular is linked to node.js, which interacts with mongodb to fetch data successfully. However, I am now faced with the challenge of mapping variables in my typescript component to the backend node.js. When viewing the data structure in the browser consol ...

javascriptnode.jsangulartypescript

Tips for retrieving the hyperlink within an HTML anchor tag using JavaScript

Here's some HTML with JavaScript: document.addEventListener('mousedown', function(event) { let elem = event.target; let jsonObject = { Key: 'mousedown', Value: event.button }; if (event.button == 2) { console ...

javascripthtmlmouseeventhref

wordpress widget that triggers a function when a click event occurs on jquery

I'm facing an issue where this function works perfectly in my header, but seems to have no effect when used in a widget $("#myID").click(function(){ var name = $("#name").val(); var phone = $("#phone").val(); console.log(name +" "+ phone) ...

javascriptphpjqueryajaxwordpress

The Vue.js array matching method

I am attempting to populate my form with the corresponding values from 'myproduct' where the id_product matches the input. However, when I run the code, the value is not returned. Can anyone spot what's wrong with my code? this.products.forE ...

javascriptarraysvue.jsfor-loop

Executing a PUT XMLHttpRequest request results in an empty response being logged to the

I've been struggling to send a PUT request using XMLHttpRequest, but I keep getting an empty response. I'm using JS for the front end and nodejs for the backend. Even though the network section in the dev tools shows that the PUT request is okay, ...

javascriptnode.jsexpress

Having trouble converting a timestamp to a date in JavaScript

My database uses MongoDB and has a timestamp field with unique formats, such as: 1657479170.7300725 1657479170.7301126 1657479170.7301197 1657479170.9120467 1657479170.932398 Converting these timestamps to the date format YYYY-MM-DD yields the correct res ...

javascriptmongodbdatetimestamp

Icons not appearing in TinyMce

Currently, I am utilizing Laravel in combination with Blade and Vue.js, specifically the tinymce-wrapper @tinymce/tinymce-vue. The Issue: Following a transition from cloud to self-hosted, TinyMce (version 5.7.0) is not displaying icons as expected. <te ...

javascriptlaravelvue.jslaravel-bladetinymce-5

What could be the cause of a JSON string only returning the final object when evaluated?

Does anyone have insight into why only the last object in my json string is returned when I use the eval function? ...

javascriptjson