359137 - Bug 357947 can be used for an XSS attack

Status: RESOLVED FIXED

(Core :: Security, defect)

Description

[moz_bug_r_a4]

A Function constructor that came from an outer window can be used to create a
function whose global object is the outer window.  Such function can be used
for an XSS attack.  See also Bug 311024.

Bug 357947 was already fixed on trunk in Bug 355161.  Thus, a testcase works
only on fx2.0.

Comment 1

[moz_bug_r_a4]

Attachment: testcase - page B (this will be opened by page A)

Comment 2

[moz_bug_r_a4]

Attachment: testcase - page A

This tries to get cookies for www.mozilla.com.

Comment 3

[moz_bug_r_a4]

An attacker can perform the XSS attack without user interaction.

It seems that Function can refer to the outer window's Function only when the
window has been opened by window.open().  Since the popup blocker is turned on
by default, my first testcase requires user interaction.

But, window.toString.constructor refers to the outer window's Function even
when the window is a subframe.  Thus, an attacker can exploit without user
interaction.

Comment 4

[moz_bug_r_a4]

Attachment: testcase 2 - using window.toString.constructor

This does not require user interaction to exploit.

Comment 5

[Daniel Veditz [:dveditz]]

Does this apply to the 1.8.0 branch? bug 355161 is claimed to be a regression from bug 343417 that never landed there. Need to test (no time now). plussing for 1.8.1.1

Comment 6

[moz_bug_r_a4]

On 1.5.0.8, I cannot get outer window's Function. (though I don't understand
how window.toString.constructor refers to outer window's Function with the fix
for bug 343417.)

Comment 7

[Daniel Veditz [:dveditz]]

We're saying we don't need this one on the 1.8.0 branch

Comment 8

[Daniel Veditz [:dveditz]]

bug 355161 has been fixed on the 1.8 branch, this one ought to be fixed by that as well. Needs to be verified.

Comment 9

[Jay Patel [:jay]]

v.fixed on 1.8 branch with Mozilla/5.0 (Macintosh; U; Intel Mac OS X; en-US; rv:1.8.1.1pre) Gecko/20061201 BonEcho/2.0.0.1pre, no exploit with testcase 2.

Comment 10

[Daniel Veditz [:dveditz]]

This bug is fixed now

Comment 11

[chris hofmann]

pvnick is doing a bit of research on XSS and also gathering up bugs with security related test cases to help add to the regression/certification test suites.  adding him to the cc list in these...