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I'm playing with bypassSecurityTrust* functions of Angular. Goal is to get a script tag to execute on the page. But it either keeps sanitizing with the message

WARNING: sanitizing HTML stripped some content

or I see in the console a

SafeHtmlImpl {changingThisBreaksApplicationSecurity: "<script>alert(1)</script>.

Goal is to get this working.

What I currently use and tried:

@Pipe({ name: 'safeHtml'})
export class SafeHtmlPipe implements PipeTransform  {
  constructor(private sanitized: DomSanitizer) {}
  transform(value: string): string {
    console.log(this.sanitized.sanitize(SecurityContext.NONE, value))
    return this.sanitized.sanitize(SecurityContext.NONE, value);
  }
}
@Component({
  selector: 'app-demo',
  templateUrl: './demoponent.html',
  styleUrls: ['./demoponent.css']
})
export class DemoComponent implements OnInit {

  name: string;
  html: string;
  constructor(private sanitizer: DomSanitizer) {
    this.name = 'Angular2';
    this.html = "<script> alert(8) </script>";
  }
  ngOnInit() {
  }
}

and the template html:

<div [innerHtml]="html | safeHtml"></div>

I tried both sanitize with SecurityContext.NONE which should work looking at the code and bypassSecurityTrustHtml(value). The above code was inspired by this answer.

Any ideas on how to execute that JavaScript?

I'm playing with bypassSecurityTrust* functions of Angular. Goal is to get a script tag to execute on the page. But it either keeps sanitizing with the message

WARNING: sanitizing HTML stripped some content

or I see in the console a

SafeHtmlImpl {changingThisBreaksApplicationSecurity: "<script>alert(1)</script>.

Goal is to get this working.

What I currently use and tried:

@Pipe({ name: 'safeHtml'})
export class SafeHtmlPipe implements PipeTransform  {
  constructor(private sanitized: DomSanitizer) {}
  transform(value: string): string {
    console.log(this.sanitized.sanitize(SecurityContext.NONE, value))
    return this.sanitized.sanitize(SecurityContext.NONE, value);
  }
}
@Component({
  selector: 'app-demo',
  templateUrl: './demo.ponent.html',
  styleUrls: ['./demo.ponent.css']
})
export class DemoComponent implements OnInit {

  name: string;
  html: string;
  constructor(private sanitizer: DomSanitizer) {
    this.name = 'Angular2';
    this.html = "<script> alert(8) </script>";
  }
  ngOnInit() {
  }
}

and the template html:

<div [innerHtml]="html | safeHtml"></div>

I tried both sanitize with SecurityContext.NONE which should work looking at the code and bypassSecurityTrustHtml(value). The above code was inspired by this answer.

Any ideas on how to execute that JavaScript?

• javascript
• html
• angular
• angular-dom-sanitizer

Share Improve this question Follow edited Sep 17, 2018 at 20:07 Machavity♦ 31.7k2727 gold badges9595 silver badges105105 bronze badges asked Apr 19, 2018 at 14:09 user857990user857990 1,22033 gold badges1515 silver badges3131 bronze badges 3

• I don't think the sanitizer is the thing that is stopping this from working. It's the regular HTML spec that says <scripts>s added in innerHTML won't be executed. See :Can scripts be inserted with innerHTML? and my answer to this question: Why doesn't a browser run a <script> in an HTML fragment retrieved via fetch API?. – zero298 Commented Apr 19, 2018 at 14:17
• So how could I put the string on the page? – user857990 Commented Apr 24, 2018 at 8:24
• <div id="attack8"> {{ html | safeHtml }} </div> doesn't work either. Again the changingThisBreaksApplicationSecurity message. – user857990 Commented Apr 24, 2018 at 8:29

Add a ment  | 

1 Answer 1

Sorted by: Reset to default 2

So yes, innerHtml can't insert script tags, but it doesn't stop it from one of the many other ways to inject JavaScript.

Working example:

import { Component, Pipe, PipeTransform, SecurityContext} from '@angular/core';
import { DomSanitizer } from '@angular/platform-browser'

@Pipe({ name: 'safeHtml'})
export class SafeHtmlPipe implements PipeTransform  {
  constructor(private sanitized: DomSanitizer) {}
  transform(value: string) {
    console.log(this.sanitized.bypassSecurityTrustHtml(value));
    return this.sanitized.bypassSecurityTrustHtml(value);
  }
}

@Component({
  selector: 'app-demo',
  template: `
    <div [innerHtml]="html | safeHtml">
    </div>
  `
})

export class DemoComponent {

  html: string;
  h_html: string;
  constructor(private sanitizer: DomSanitizer) {
    this.html = "<svg onload=\"alert(1)\"> blah </svg>"
    this.h_html = sanitizer.sanitize(SecurityContext.HTML, "<svg onload=\"alert(2)\"> blah </svg>');
  }
}

What doesn't work is

return this.sanitized.sanitize(SecurityContext.HTML, value);

or using

<div [innerHtml]="h_tmpl"></div>

Not sure why. Should behave the same afaiu.

I'm playing with bypassSecurityTrust* functions of Angular. Goal is to get a script tag to execute on the page. But it either keeps sanitizing with the message

WARNING: sanitizing HTML stripped some content

or I see in the console a

SafeHtmlImpl {changingThisBreaksApplicationSecurity: "<script>alert(1)</script>.

Goal is to get this working.

What I currently use and tried:

@Pipe({ name: 'safeHtml'})
export class SafeHtmlPipe implements PipeTransform  {
  constructor(private sanitized: DomSanitizer) {}
  transform(value: string): string {
    console.log(this.sanitized.sanitize(SecurityContext.NONE, value))
    return this.sanitized.sanitize(SecurityContext.NONE, value);
  }
}
@Component({
  selector: 'app-demo',
  templateUrl: './demoponent.html',
  styleUrls: ['./demoponent.css']
})
export class DemoComponent implements OnInit {

  name: string;
  html: string;
  constructor(private sanitizer: DomSanitizer) {
    this.name = 'Angular2';
    this.html = "<script> alert(8) </script>";
  }
  ngOnInit() {
  }
}

and the template html:

<div [innerHtml]="html | safeHtml"></div>

I tried both sanitize with SecurityContext.NONE which should work looking at the code and bypassSecurityTrustHtml(value). The above code was inspired by this answer.

Any ideas on how to execute that JavaScript?

I'm playing with bypassSecurityTrust* functions of Angular. Goal is to get a script tag to execute on the page. But it either keeps sanitizing with the message

WARNING: sanitizing HTML stripped some content

or I see in the console a

SafeHtmlImpl {changingThisBreaksApplicationSecurity: "<script>alert(1)</script>.

Goal is to get this working.

What I currently use and tried:

@Pipe({ name: 'safeHtml'})
export class SafeHtmlPipe implements PipeTransform  {
  constructor(private sanitized: DomSanitizer) {}
  transform(value: string): string {
    console.log(this.sanitized.sanitize(SecurityContext.NONE, value))
    return this.sanitized.sanitize(SecurityContext.NONE, value);
  }
}
@Component({
  selector: 'app-demo',
  templateUrl: './demo.ponent.html',
  styleUrls: ['./demo.ponent.css']
})
export class DemoComponent implements OnInit {

  name: string;
  html: string;
  constructor(private sanitizer: DomSanitizer) {
    this.name = 'Angular2';
    this.html = "<script> alert(8) </script>";
  }
  ngOnInit() {
  }
}

and the template html:

<div [innerHtml]="html | safeHtml"></div>

I tried both sanitize with SecurityContext.NONE which should work looking at the code and bypassSecurityTrustHtml(value). The above code was inspired by this answer.

Any ideas on how to execute that JavaScript?

• javascript
• html
• angular
• angular-dom-sanitizer

Share Improve this question Follow edited Sep 17, 2018 at 20:07 Machavity♦ 31.7k2727 gold badges9595 silver badges105105 bronze badges asked Apr 19, 2018 at 14:09 user857990user857990 1,22033 gold badges1515 silver badges3131 bronze badges 3

• I don't think the sanitizer is the thing that is stopping this from working. It's the regular HTML spec that says <scripts>s added in innerHTML won't be executed. See :Can scripts be inserted with innerHTML? and my answer to this question: Why doesn't a browser run a <script> in an HTML fragment retrieved via fetch API?. – zero298 Commented Apr 19, 2018 at 14:17
• So how could I put the string on the page? – user857990 Commented Apr 24, 2018 at 8:24
• <div id="attack8"> {{ html | safeHtml }} </div> doesn't work either. Again the changingThisBreaksApplicationSecurity message. – user857990 Commented Apr 24, 2018 at 8:29

Add a ment  | 

1 Answer 1

Sorted by: Reset to default 2

So yes, innerHtml can't insert script tags, but it doesn't stop it from one of the many other ways to inject JavaScript.

Working example:

import { Component, Pipe, PipeTransform, SecurityContext} from '@angular/core';
import { DomSanitizer } from '@angular/platform-browser'

@Pipe({ name: 'safeHtml'})
export class SafeHtmlPipe implements PipeTransform  {
  constructor(private sanitized: DomSanitizer) {}
  transform(value: string) {
    console.log(this.sanitized.bypassSecurityTrustHtml(value));
    return this.sanitized.bypassSecurityTrustHtml(value);
  }
}

@Component({
  selector: 'app-demo',
  template: `
    <div [innerHtml]="html | safeHtml">
    </div>
  `
})

export class DemoComponent {

  html: string;
  h_html: string;
  constructor(private sanitizer: DomSanitizer) {
    this.html = "<svg onload=\"alert(1)\"> blah </svg>"
    this.h_html = sanitizer.sanitize(SecurityContext.HTML, "<svg onload=\"alert(2)\"> blah </svg>');
  }
}

What doesn't work is

return this.sanitized.sanitize(SecurityContext.HTML, value);

or using

<div [innerHtml]="h_tmpl"></div>

Not sure why. Should behave the same afaiu.

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