Mozilla has released a security advisory and updated software to address the Mozilla Firefox just-in-time JavaScript parsing arbitrary code execution vulnerability.
Description
Mozilla Firefox version 3.5 contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code.
The vulnerability is due to an error in the just-in-time (JIT) JavaScript compiler used by the TraceMonkey JavaScript engine when processing HTML elements. An unauthenticated, remote attacker could exploit the vulnerability by convincing a user to visit a malicious website. A successful exploit could allow the attacker to execute arbitrary code with the privileges of the user.
Proof-of-concept code to exploit the vulnerability is publicly available.
Mozilla has confirmed the vulnerability and released updated software.
Warning Indicators
Mozilla Firefox version 3.5 is vulnerable.
IntelliShield Analysis
Limited information is available to describe this vulnerability. To exploit the vulnerability, an attacker must convince a user to visit a malicious web page. The attacker will likely employ social engineering to exploit the vulnerability, such as supplying links to the website in an e-mail message or another form of messaging.
An exploit could allow an unauthenticated, remote attacker to execute arbitrary code with the privileges of the user running Mozilla Firefox. If the user holds Administrator privileges, an exploit could result in complete system compromise.
Vendor Announcements
Mozilla has released a security advisory at the following link: MFSA 2009-41
US-CERT has released a vulnerability note at the following link: VU#443060
Impact
An unauthenticated, remote attacker could exploit this vulnerability to execute arbitrary code with the privileges of the user. If the user holds elevated privileges, the attacker could execute code that results in a complete system compromise.
Technical Information
The vulnerability exists when the application returns from a native function such as escape(). Upon this return, the JIT compiler could fall into a corrupt state.
An unauthenticated, remote attacker could exploit this vulnerability to execute arbitrary code with user privileges.
Safeguards
Administrators are advised to apply the appropriate updates.
Users are advised not to follow unsolicited links. Users should verify the authenticity of unexpected links prior to following them.
Users are advised not to open e-mail messages from untrusted sources.
Administrators are advised to monitor affected systems.
Users may disable the just-in-time JavaScript compiler by running Mozilla Firefox in safe mode or by setting the javascript.options.jit.content value to false through the about:config interface.
Version 2, July 15, 2009, 12:06 PM: Mozilla has released a security notice and provided workarounds to address the just-in-time JavaScript parsing arbitrary code execution vulnerability. US-CERT has released a vulnerability note.
Version 1, July 14, 2009, 11:29 AM: Mozilla Firefox contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code. Updates are unavailable.
The security vulnerability applies to the following combinations of products.
Primary Products:
Mozilla Foundation
Firefox
3.5 .0
Associated Products:
N/A
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