Mozilla Firefox onUnload Event and document.write() Race Condition May Let Remote Users Execute Arbitrary Code
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SecurityTracker Alert ID: 1017701 |
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SecurityTracker URL: http://securitytracker.com/id/1017701
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CVE Reference:
CVE-2007-1092
(Links to External Site)
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Updated: May 18 2008
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Original Entry Date: Feb 26 2007
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Impact:
Execution of arbitrary code via network, User access via network
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Fix Available: Yes Vendor Confirmed: Yes Exploit Included: Yes
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Version(s): 1.5.0.9 and 2.0.0.1 only
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Description:
A vulnerability was reported in Mozilla Firefox. A remote user may be able to cause arbitrary code to be executed on the target user's system.
A remote user can create specially crafted HTML that, when loaded by the target user, will trigger a memory corruption error and potentially execute arbitrary code on the target system. The code will run with the privileges of the target user.
A race condition between the onUnload event handler and self-modifying document.write() calls can trigger the vulnerability.
The vulnerability was introduced in Firefox 2.0.0.1 and 1.5.0.9. Earlier versions are not affected.
A demonstration exploit is available at:
http://lcamtuf.coredump.cx/ietrap/testme.html
Michal Zalewski reported this vulnerability.
The Mozilla bug report is available at:
https://bugzilla.mozilla.org/show_bug.cgi?id=371321
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Impact:
A remote user can create HTML that, when loaded by the target user, will execute arbitrary code on the target user's system.
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Solution:
The vendor has issued a fix (1.5.0.10, 2.0.0.2).
The Mozilla advisory is available at:
http://www.mozilla.org/security/announce/2007/mfsa2007-08.html
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Vendor URL: www.mozilla.org/security/announce/2007/mfsa2007-08.html (Links to External Site)
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Cause:
Boundary error
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Underlying OS: Linux (Any), UNIX (Any), Windows (Any)
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Message History:
None.
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Source Message Contents
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Subject: [Full-disclosure] Firefox onUnload + document.write() memory
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While researching my previous report on MSIE7 browser entrapment, I
noticed that Firefox is susceptible to a pretty nasty, and apparently
easily exploitable memory corruption vulnerability. When a location
transition occurs and the structure of a document is modified from within
onUnload event handler, freed memory structures are left in inconsistent
state, possibly leading to a remote compromise.
A quick test case that crashes while trying to follow partly
user-dependent corrupted pointers near valid memory regions (can be forced
to write, too):
http://lcamtuf.coredump.cx/ietrap/testme.html
This also crashes MSIE7 with a seemingly harmless NULL pointer bug (didn't
research it - do your homework).
Firefox problem is being tracked here:
https://bugzilla.mozilla.org/show_bug.cgi?id=371321
/mz
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