NIST Site Search
Search NIST.GOV
Custom Search
[Official NIST.GOV TIME]
Product Research

Advertise on this site
Firefox JavaScript Reentrant Vulnerability
Two Hackers at the ToorCon hacker conference demonstrated a flaw in Firefox that could lead to arbitrary code execution. The problem is with how Firefox implements JavaScript. Easy mitigation step, see below. (Updates: Proof of Concept code posted... The two hackers may have overstated the problem.) No Longer Supported
If you just want the skinny on the Firefox vulnerability click here. We're starting off with a little background on Javascript. See important Updates below.

We've said it many times before, the Internet is not a safe place, diligence is key. Though we feel that Firefox is more secure than Internet Explorer this is large part due to the lack of ActiveX support. But there are many other avenues to attack the web browser other than ActiveX. One of those is Javascript. Javascript is a interpreted programming language that works on the client side of the connection (as opposed to the server side). When your web browser loads a web page and sees Javascript on the page it interprets the code and does what its told to do. This sounds inherently dangerous since you have no control over what may be hidden in the HTML of some web page. But Javascript was written from the ground up to run within the confines of the web browser and as such its powers are limited. Most often used for simple tasks such as mouse rollovers (eg; changing a graphic when you highlight a button, or changing a text color when you float the cursor over the text) or validating form input. It is also often used in flyout style menus. It is usually harmless.

But the bad guys have figured out ways to use it maliciously. One such use is in Cross-Site Scripting (XSS) where Javascript is fed through some site's form entry (etc) that will echo it back to the user. When this is done it appears that whatever the Javascript did in the browser actually came from the website. So when you think you are entering your pin number on the banks site you may actually be entering it on the phishing / hackers site (there are other malicious uses for XSS as well). XSS vulnerable sites are everywhere. This author went hunting for them and found 2 major media sites that are vulnerable in less than 20 minutes.

Because Javascript must be interpreted by the browser to do things any oversight on the part of the browser programmers could be disastrous. A simple example would be Javascript used to load an image, if that routine could instead be used to load a local file with parameters a hacker could use this to run commands to download and start any malicious content they wanted. This would, in affect, make Javascript as dangerous as ActiveX (ActiveX can do almost anything if you let it. Its very powerful, it can also be very dangerous if used or configured incorrectly). These type problems with Javascript are rare but have come up from time to time.

Latest Firefox JavaScript Reentrant Vulnerability: (see updates below)

Two self-professed hackers, Mischa Spiegelmock and Andrew Wbeelsoi, gave a slide show at the ToorCon hacker conference showing Firefox being exploited to run arbitrary code. According to Spiegelmock the Firefox Javascript implementation is a "complete mess," and "is impossible to patch." Of course this this comes from a couple of hackers who's presentation was described on ToorCon as "New ways of getting your load onto your quivering victim's stack Reaching into the hearts and minds (also the genitals) of users" and comments in the slide presentation like "Hahahahahahaha stick that in your pipes and smoke it Firefox fanboys!". According to people who saw the presentation it appeared to show enough to figure out how to recreate the exploit. So far the vulnerability has not been confirmed and it is possible this is all a ruse or greatly exaggerated. But the folks at Mozilla seem to have seen enough to be taking this serious.

Of course this could also be the real deal. If that is the case Firefox has a very potent vulnerability just waiting to be exploited. Javascript can often be loaded in to bulletin board posts and blogs so random surfing would not be safe. Of course it can also be used in targeted attacks via eMail links, or loaded on to compromised web servers. It will be imperative that this get fixed quickly. If you are using a pre-1.5 version of Firefox and don't want to upgrade you should install the NoScript Extension (see below) immediately. Firefox 1.5x will be updated to fix this problem, previous versions will not.

The vulnerability as presented could lead to running arbitrary executable code within the security context of the user. In other words make Firefox install whatever the bad guys want installed assuming your login has the rights to install software.

Mitigation:
  • If you run Firefox you should immediately install the NoScript Extension. This script will prompt you when a page tries to run Javascript and give you the option to let it run. You can tell it to run just for this browser session or you can whitelist the site so that it always runs Javascript from that site. Some sites are very dependent on Javascript and won't show you anything without it. Some sites display nicely without it. We recommend whitelisting sites you visit often. Unless you do you'll never know what content you're missing out on. Some of the content might load using standard HTML, other content might load using JavaScript. For instance this site uses Javascript in several of the sidebar boxes.
  • You could use Internet Explorer since it is not vulnerable to this particular bug. But it currently has several unpatched vulnerabilities of its own. Since it still commands about 75-80% of the browser market hackers often target its vulnerabilities harder than those in Firefox (besides their is a "stick it to the man" mentality in attacking MS).


References:


Updates:
  • If you can't trust a couple of hackers who can you trust!! Quotes from Mozilla's interview with one of the two hackers that gave the presentation: "The main purpose of our talk was to be humorous." "I personally have not gotten it to result in code execution, nor do I know of anyone who has." The PoC can lead to a browser crash. They also admitted to not having "30 undisclosed Firefox vulnerabilities".
  • Proof of Concept code has been posted on the web. Now its only a matter of time before this vulnerability is exploited in the wild.


Vulnerable - Windows, Mac, Linux. Apparently all versions of Firefox.

Share or Bookmark this Article Using:
No Longer Supported



Google
WebNIST.org
NIST.govSecurityFocus.com





Posted by NIST.org on Monday 02 October 2006 - 04:13:29 | |printer friendly
Translate to: French German Italian Spanish Portuguese GTM_LAN_DUTCH Russian Chinese Arabic Korean English
Google Ads




Headlines

»NIST Awards Contract to MITRE to Support Cybersecurity Center of Excellence
»NCCoE Fall Open House
»NCCoE Seeks Comments on Mobile Device Security Building Block
»Three Pilot Projects Receive Grants to Improve Online Security and Privacy
»NIST Megacities Carbon Project Named aposProject to Watchapos by United Nations
»NIST Announces FY 2014 Small Business Innovation Research Awards
»NIST Helps Develop New Standard for Microsensor Technology
»New Forensic Subcommittee on Digital Evidence Added to Organization of Scientific Area Committees
»NIST Team Honored for Work on Military Smartphone Apps, Security
»NIST Vetting Guide Helps in Testing Mobile Apps to Learn What They Really Do
»NIST, IAPP Host Privacy Engineering Workshop in September 2014
»NIST Therapy for Ultraviolet Laser Beams: Hydrogen-treated Fibers
»NIST aposGlobal City Teams Challengeapos to Create Smart Cities
»Global City Teams Challenge Workshop
»Updated NIST Guide Provides Computer Security Assessment Procedures for Core Security Controls


Date published: not known
Details

»Apple Releases OS X bash Update 1.0
Original release date: September 30, 2014 Apple has released OS X bash Update 1.0 to address ...
»Bourne-Again Shell (Bash) Remote Code Execution Vulnerability
Original release date: September 24, 2014 | Last revised: September 30, 2014 US-CERT is aware ...
»Mozilla Network Security Services (NSS) Library Vulnerability
Original release date: September 24, 2014 A vulnerability in the Mozilla NSS library could al ...
»Apple Releases Security Updates for iOS, Apple TV, and Xcode
Original release date: September 18, 2014 Apple released security updates for iOS devices, Ap ...
»Adobe Releases Security Updates for Adobe Reader and Acrobat
Original release date: September 16, 2014 Adobe has released security updates for Adobe Reade ...
»Cisco Integrated Management Controller Vulnerability
Original release date: September 11, 2014 Cisco has released an advisory to address a vulnera ...
»Google Releases Security Update for Chrome
Original release date: September 10, 2014 Google has released Chrome 37.0.2062.120 for Window ...
»Adobe Releases Security Updates for Flash Player and Air
Original release date: September 09, 2014 Adobe has released security updates to address mult ...
»Microsoft Releases September 2014 Security Bulletin
Original release date: September 09, 2014 Microsoft released updates to address vulnerabiliti ...
»WordPress Releases Security Update
Original release date: September 04, 2014 WordPress 3.9.2 has been released to address multip ...


Date published: not known
Details

»VB2014: Slides day three
Thanks all for a fantastic conference and see you in Prague... or in Denver! Two days ago, a lively ...
»'Windigo' research wins first annual Péter Szőr award
The first of many awards to commemorate brilliant researcher. When, in November last year, we heard ...
»VB2014: Slides day two
Another day of excellent presentations. The second day of VB2014 was just as successful as the first ...
»VB2014: Slides day one
Almost £1,300 donated to WWF! The inaugural Virus Bulletin conference was held in 1991, making ...
»VB2014 previews: an overview
Fourteen blog posts look ahead at the 24th Virus Bulletin conference. In just a few more hours, dele ...
»VB2014 preview: Tech Support Scams 2.0: an inside look into the evolution of the classic Microsoft tech support scam
Jérôme Segura looks at recent developments in malicious cold calls. In the weeks running u ...
»VB2014 preview: Ubiquitous Flash, ubiquitous exploits and ubiquitous mitigation
Chun Feng and Elia Florio look at exploits targeting domain memory opcode in Adobe Flash. In the wee ...
»VB2014: frequently asked questions
Some useful information for those attending VB2014 - or those interested in attending. I haven't reg ...
»VB2014 preview: two papers on Linux server malware
Researchers from ESET, Yandex and Symantec look at emerging malware trend. In the weeks running up t ...


Date published: not known
Details

»How A Major Bank Hacked Its Java Security
Deutsche Bank London helped create a new application self-defense tool to lock down and virtually pa ...
»Black Hat Trainings
https://www.blackhat.com/tr-14/
»Retailers Realize EMV Won't Save Them From Fraudsters
Fraudsters hit retailers harder than ever in 2014 and many recognize that even though EMV's chip-and ...
»Software Assurance: Time to Raise the Bar on Static Analysis
The results from tools studies suggest that using multiple tools together can produce more powerful ...
»How To Hack A Human
Social engineering expert and founder of the DEF CON Social Engineering Capture the Flag contest Chr ...
»Bashed & Shellshocked
»Be Aware: 8 Tips for Security Awareness Training
Hint: One giant security training session to rule them all is not the way to go.
»New Bash Bugs Surface
Time to patch again--newly discovered flaws in Bash put Linux-based systems at risk.
»Making Sense Of Shellshock Attack Chaos
Attacks against the Bash bug increase in volume and variety, with an emphasis on information gatheri ...


Date published: Wed, 01 Oct 2014 05:46:17 EDT
Details
Main Menu
· Home
Current Security News
 
SANS Internet Storm Center, InfoCON: green

» Infocon: green

» VMware security advisory: VMSA-2014-0010 http://www.vmware.com/security/advisories/VMSA-2014-0010.html, (Wed, Oct 1st)
[30 Sep 2014 10:10pm]

» ISC StormCast for Wednesday, October 1st 2014 http://isc.sans.edu/podcastdetail.html?id=4171, (Wed, Oct 1st)
[30 Sep 2014 06:27pm]

» DerbyCon highlights, (Tue, Sep 30th)
[30 Sep 2014 05:59pm]

» ISC threat level returned to green - ShellShock message traffic subsiding, recommend focus on patching and monitoring, (Tue, Sep 30th)
[30 Sep 2014 03:43pm]

» ISC StormCast for Tuesday, September 30th 2014 http://isc.sans.edu/podcastdetail.html?id=4169, (Tue, Sep 30th)
[29 Sep 2014 06:27pm]

» Apple Released Update to Fix Shellshock Vulnerability http://support.apple.com/kb/DL1769, (Mon, Sep 29th)
[29 Sep 2014 03:54pm]

» Shellshock: Updated Webcast (Now 6 bash related CVEs!), (Mon, Sep 29th)
[29 Sep 2014 01:41pm]

» Shellshock: A Collection of Exploits seen in the wild, (Mon, Sep 29th)
[29 Sep 2014 09:05am]

» Shellshock: We are not done yet CVE-2014-6277, CVE-2014-6278, (Mon, Sep 29th)
[29 Sep 2014 08:14am]

» Shellshock: Vulnerable Systems you may have missed and how to move forward, (Mon, Sep 29th)
[29 Sep 2014 08:14am]

***
CNET News.com

» Microsoft defends opening Hotmail account of blogger in espionage case
[20 Mar 2014 06:47pm]

» Syria's Internet goes dark for several hours
[20 Mar 2014 04:25pm]

» Symantec fires CEO Steve Bennett
[20 Mar 2014 03:07pm]

» Microsoft sniffed blogger's Hotmail account to trace leak
[20 Mar 2014 01:28pm]

» Microsoft sniffed private Hotmail account to trace trade secret leak
[20 Mar 2014 01:28pm]

» IBM's new services zero in on fraud, financial crime
[20 Mar 2014 07:31am]

» Despite assault on privacy, Page sees value in online openness
[19 Mar 2014 08:00pm]

» Hackers transform EA Web page into Apple ID phishing scheme
[19 Mar 2014 05:21pm]

» NSA top lawyer says tech giants knew about data collection
[19 Mar 2014 02:57pm]

» Microsoft touts study showing the cost of pirated software
[19 Mar 2014 06:55am]

» Microsoft touts study showing cost of malware in pirated software
[19 Mar 2014 06:55am]

» How to spy on your lover, the smartphone way
[18 Mar 2014 01:24pm]

» Mt. Gox update lets users see their Bitcoin balances
[18 Mar 2014 06:38am]

» Fake Malaysia Airlines links spread malware
[17 Mar 2014 05:12pm]

» IBM: No, we did not help NSA spy on customers
[17 Mar 2014 01:15pm]

***

***



***


More IT Security
News Feeds
More Sponsors

Advertise on this site
RSS Feeds
Our news can be syndicated by using these rss feeds.
rss1.0
rss2.0
rdf
Symantec News

NIST.org is in no way connected to the U.S. government site NIST.gov

This site is © John Herron, CISSP. All Rights Reserved.

Please visit daily to stay up to date on all your IT Security compliance issues.

http://www.nist.org -
Hosted by BlueHost. We've never had a better hosting company.
{THEMEDISCLAIMER}