Bugtraq mailing list archives
Re: Re[4]: DoS vulnerabilities in Firefox, Internet Explorer, Chrome, Opera and other browsers
From: "John Smith" <at-x () live com>
Date: Sat, 29 May 2010 02:57:35 +0530
Hi Vladimir, Thanks for your views.I was carried away because the author used scripts (in a global script tag) in the PoC of the issue in question which made unconditional recursion possible. Without scripts enabled, if iframe's src property is set to itself(?), it is parsed upto 1 level (i.e. not recursed). Hence it doesn't affect or DoS the latest browsers (the best I can say...).
A few other points:1. if a links/ads or any other content-syndication provider allow unverified javascript to be served, DoS would be the least of the concern (read: it’s the breeding ground of XSS exploits) 2. I more than agree that an issue to be classified as a security vulnerability if a combination of tags/properties/scripts causes or is capable of causing malice in any form while conforming to the standards (which isn't the case here). 3. Just to reiterate my earlier post, DoS is more of an annoyance than malice. If the issue noted in this context DoS by a form of unconditional recursion (or infinite loop) to create 'out of memory' or stack overflow sortof situation (though modern uri handlers handle it gracefully) but requires a task kill operation on the script engine's host (the browser in this context).
Sadly, there're too many known unknowns to the #2 above which involves the support of non-standard techniques like Anti-Phishing Working Group/SmartScreen filter etc which doesn't attempt to or can be absolutely 100% fool-proof...
Best Regards, wPS: Lets put IE6 out of context, I'm not sure why it is still brought up or why it's still used, because it’s a browser from the times when the first ancestor of Firefox (Phoenix) didn't exist. Yes, its that ancient! :)
-------------------------------------------------- From: "Vladimir '3APA3A' Dubrovin" <3APA3A () SECURITY NNOV RU> Sent: Saturday, May 29, 2010 2:05 AM To: "John Smith" <at-x () live com>Cc: "MustLive" <mustlive () websecurity com ua>; "Susan Bradley" <sbradcpa () pacbell net>; <bugtraq () securityfocus com> Subject: Re[4]: DoS vulnerabilities in Firefox, Internet Explorer, Chrome, Opera and other browsers
Dear John Smith, In general case we are discussing, DoS may be caused by e.g. some combination of allowed tags/properties or by malformed image. As it was pointed by author, this attack may be performed with scripting disabled (with [iframe src=]). That's why e-mail vector may be significant. --Friday, May 28, 2010, 11:55:28 PM, you wrote to 3APA3A () SECURITY NNOV RU: JS> Point taken. But that'd be a non-issue on the browser's end as much asJS> site's that is allowing the rogue scripts (or malformed ads, as per yourJS> example).JS> The fork of this mail thread clearly explains what I'm talking about. The JS> issue noted there is a simple DoS attack which every programming language JS> and platform is vulnerable too. Its called the "infinite loop". It is not a JS> 'security vulnerability' by itself and is completely agnostic of the uriJS> handler (try http or anything instead of nntp).JS> Here's the simplified JS version of it (lets call it the Universal DoS --JS> yes, it'd work for every browser on the planet that can execute JS) - JS> <script> JS> while(1)alert('hello world'); JS> </script> JS> Done! JS> Workaround:JS> None very intuitive. Maybe allow the user to terminate the script at everyJS> iteration? specific time period? etc... JS> -------------------------------------------------- JS> From: "Vladimir '3APA3A' Dubrovin" <3APA3A () SECURITY NNOV RU> JS> Sent: Friday, May 28, 2010 11:47 PM JS> To: "John Smith" <at-x () live com> JS> Cc: "MustLive" <mustlive () websecurity com ua>; "Susan Bradley" JS> <sbradcpa () pacbell net>; <bugtraq () securityfocus com>JS> Subject: Re[2]: DoS vulnerabilities in Firefox, Internet Explorer, Chrome,JS> Opera and other browsersDear John Smith, Actually, browser DoS may be quite serious vulnerability, depending on nature of DoS. Think about e.g. banner or content exchange network, social networks, web boards, etc where browser vulnerability may be used against site or page because it will harm any visitors of this site or page. In case of this very vulnerability, most serious impact may be from e-mail vector. --Friday, May 28, 2010, 7:07:50 PM, you wrote to mustlive () websecurity com ua:JS> Just a few cents - DoS in webbrowsers doesn't fall under the categoryof JS> "vulnerabilities" rather more of "annoyances". Although I don't deny the JS> fact that certain DoS attacks *may lead* or *may serve as hints* to other JS> more serious exploits, but that's a different topic and with ASLR in the JS> scene, a very grey area of discussion. -- Skype: Vladimir.Dubrovin ~/ZARAZA http://securityvulns.com/ Стреляя во второй раз, он искалечил постороннего. Посторонним был я. (Твен)-- Skype: Vladimir.Dubrovin ~/ZARAZA http://securityvulns.com/ Машина оказалась способной к единственному действию, а именно умножению 2x2, да и то при этом ошибаясь. (Лем)
Current thread:
- DoS vulnerabilities in Firefox, Internet Explorer, Chrome, Opera and other browsers MustLive (May 18)
- Re: DoS vulnerabilities in Firefox, Internet Explorer, Chrome, Opera and other browsers Susan Bradley (May 18)
- Re: DoS vulnerabilities in Firefox, Internet Explorer, Chrome, Opera and other browsers MustLive (May 20)
- Re: DoS vulnerabilities in Firefox, Internet Explorer, Chrome, Opera and other browsers Susan Bradley (May 20)
- Re: DoS vulnerabilities in Firefox, Internet Explorer, Chrome, Opera and other browsers MustLive (May 28)
- Re: DoS vulnerabilities in Firefox, Internet Explorer, Chrome, Opera and other browsers John Smith (May 28)
- Re[2]: DoS vulnerabilities in Firefox, Internet Explorer, Chrome, Opera and other browsers Vladimir '3APA3A' Dubrovin (May 28)
- Re: Re[2]: DoS vulnerabilities in Firefox, Internet Explorer, Chrome, Opera and other browsers John Smith (May 28)
- Re[4]: DoS vulnerabilities in Firefox, Internet Explorer, Chrome, Opera and other browsers Vladimir '3APA3A' Dubrovin (May 31)
- Re: Re[4]: DoS vulnerabilities in Firefox, Internet Explorer, Chrome, Opera and other browsers John Smith (May 31)
- Re: DoS vulnerabilities in Firefox, Internet Explorer, Chrome, Opera and other browsers MustLive (May 20)
- Re: DoS vulnerabilities in Firefox, Internet Explorer, Chrome, Opera and other browsers Susan Bradley (May 18)