Chromium Blog
News and developments from the open source browser project
Lossless and Transparency Modes in WebP
Thursday, August 30, 2012
Cross-posted on the
Google Developers Blog
At Google, we are constantly looking at ways to make web pages load faster. One way to do this is by making web images smaller. This is especially important for mobile devices where smaller images save both bandwidth and battery life. Earlier this month, we released
version 0.2 of the WebP library
that adds support for lossless and transparency modes to compress images. This version provides CPU and memory performance comparable to or better than PNG, yet results in
26% smaller files
.
WebP’s improved compression comes from advanced techniques such as dedicated
entropy codes
for different color channels, exploiting 2D locality of
backward reference distances
and a color cache of recently used colors. This complements basic techniques such as
dictionary coding
,
Huffman coding
and
color indexing transform
. We think that we've only scratched the surface in improving compression. Our newly added support for
alpha transparency
with lossy images promises additional gains in this space, helping make WebP an efficient replacement for PNG.
The new WebP modes are supported natively in the latest Beta version of Chrome. The
bit stream specification
for these new WebP modes has been finalized and the
container specification
has been updated. We thank the community for their valuable feedback and for helping us evolve WebP as a new image compression format for the web. We encourage you to try these new compression methods on your favorite set of images, check out the code, and continue to provide
feedback
.
Posted by Jyrki Alakuijala - Software Engineer
Octane: the JavaScript benchmark suite for the modern web
Tuesday, August 21, 2012
The web is evolving and so should the JavaScript benchmarks that measure its performance. Today, we are releasing
Octane
, a JavaScript benchmark suite that aims to measure a browser’s performance when running the complex and demanding web applications that users interact with daily.
Most of the existing JavaScript benchmarks run artificial tests that were created on an ad-hoc basis to stress a specific JavaScript feature. Octane breaks with this tradition and extends the former V8 Benchmark Suite with 5 new benchmarks created from full, unaltered [1], well-known web applications and libraries. A high score in the new benchmarks directly translates to better and smoother performance in similar web applications.
Here is an overview of the new tests:
Box2DWeb
runs a JavaScript port of a popular
2D physics engine
that is behind many well-known simulations and web games.
Mandreel
puts a JavaScript port of the 3D Bullet Engine to the test with a twist: The original C++ source code for the engine is translated to JavaScript by Onan Games’
Mandreel
compiler, which is also used in countless web-based games.
Pdf.js
is based on
Mozilla’s PDF reader
and shows how Javascript applications can replace complex native browser plug-ins. It measures how fast the browser decodes a sample PDF document.
GB Emulator
is derived from an
open source emulator
of a famous game console running a 3D demo.
CodeLoad
measures how quickly a JavaScript engine can bootstrap commonly used JavaScript libraries and start executing code in them. The source for this test is derived from open source libraries (
Closure
,
jQuery
).
Besides an expanded
set of benchmarks
, Octane also has an interface that makes it easier to read and that adapts automatically to tablet and mobile screens.
You can try out
Octane
yourself, browse the
source code
, or read more about each benchmark at the
Octane site
. Still have some questions? Have a look at the
FAQ page
.
[1]
Beside glue logic and emulation of canvas / DOM interaction where necessary.
Posted by Stefano Cazzulani, Product Manager
Announcing Pwnium 2
Wednesday, August 15, 2012
The
first Pwnium competition
held earlier this year
exceeded our expectations
. We received two submissions of such complexity and quality that both of them won
Pwnie Awards
at this year’s Black Hat industry event. Most importantly, we were able to make Chromium significantly stronger based on what we learned.
We’re therefore going to host another Pwnium competition, called... Pwnium 2. It will be held on Oct 10th, 2012 at the
Hack In The Box
10 year anniversary conference in Kuala Lumpur, Malaysia.
This time, we’ll be sponsoring up to $2 million worth of rewards at the following reward levels:
$60,000: “Full Chrome exploit”: Chrome / Win7 local OS user account persistence using only bugs in Chrome itself.
$50,000: “Partial Chrome exploit”: Chrome / Win7 local OS user account persistence using at least one bug in Chrome itself, plus other bugs. For example, a WebKit bug combined with a Windows kernel bug.
$40,000: “Non-Chrome exploit”: Flash / Windows / other. Chrome / Win7 local OS user account persistence that does not use bugs in Chrome. For example, bugs in one or more of Flash, Windows or a driver.
$Panel decision: “Incomplete exploit”: An exploit that is not reliable, or an incomplete exploit chain. For example, code execution inside the sandbox but no sandbox escape; or a working sandbox escape in isolation. For Pwnium 2, we want to reward people who get “part way” as we could definitely learn from this work. Our rewards panel will judge any such works as generously as we can.
Exploits should be demonstrated against the latest stable version of Chrome. Chrome and the underlying operating system and drivers will be fully patched and running on an Acer Aspire V5-571-6869 laptop (which we’ll be giving away to the best entry.) Exploits should be served from a password-authenticated and HTTPS Google property, such as App Engine. The bugs used must be novel i.e. not known to us or fixed on trunk. Please document the exploit.
You may have noticed that we’ve compressed the reward levels closer together for Pwnium 2. This is in response to feedback, and reflects that any local account compromise is very serious. We’re happy to make the web safer by any means -- even rewarding vulnerabilities outside of our immediate control.
Another well-received piece of feedback from the first Pwnium was that more notice would have been nice. Accordingly, we’re giving about two months notice. We hope this gives enough time for the security community to craft more
beautiful
works
, which we’d be more than happy to reward and celebrate.
Posted by Chris Evans, Software Engineer
Chromium Vulnerability Rewards Program: larger rewards!
Tuesday, August 14, 2012
The
Chromium Vulnerability Rewards Program
was created to help reward the contributions of security researchers who invest their time and effort in helping us make Chromium more secure. We’ve been very pleased with the response: Google’s various vulnerability reward programs have kept our users protected and netted more than $1 million dollars of total rewards for security researchers. Recently, we’ve seen a significant drop-off in externally reported Chromium security issues. This signals to us that bugs are becoming harder to find, as the efforts of the wider community have made Chromium significantly stronger.
Therefore, we’re making the following changes to the reward structure:
Adding a bonus of $1,000 or more on top of the base reward for “particularly exploitable” issues. The onus is on the reporter to provide a quick demonstration as part of the repro. For example, for a DOM-based use-after-free, one might use JavaScript to allocate a specific object type in the “freed” slot, resulting in a vtable dereference of 0x41414141.
Adding a bonus of $1,000 or more on top of the base reward for bugs in stable areas of the code base—see below for an example. By “stable”, we mean that the defect rate appears to be low and we think it’s harder to find a security bug in the area.
Adding a bonus of $1,000 or more on top of the base reward for serious bugs which impact a significantly wider range of products than just Chromium. For example, certain open source parsing libraries—see below for an example.
The rewards panel has always reserved the right to reward at our discretion. At times, rewards have reached the $10,000 level for
particularly significant contributions
. An extraordinary contribution could be a sustained level of bug finding, or even one individual impressive report. Examples of individual items that might impress the panel include:
Nvidia / ATI / Intel GPU driver vulnerabilities. High or critical severity vulnerabilities in the respective Windows drivers, demonstrated and triggered from a web page. Submissions on Chrome OS would also be interesting. Chrome OS typically runs on a device with an Intel GPU.
Local privilege escalation exploits in Chrome OS via the Linux kernel. Chrome OS has a stripped-down kernel, so a working exploit against it would certainly be worth examining. We reserve the right to reward more generously if the exploit works inside our “setuid sandbox” and / or our fast-evolving “seccomp BPF sandbox”.
Serious vulnerabilities in IJG libjpeg. For well over a decade, there hasn’t been a serious vulnerability against IJG libjpeg. Can one be found?
64-bit exploits. Any working code execution exploit on a 64-bit Chrome release. Sandbox escape not required.
Renderer to browser exploit. Any working browser code execution exploit, starting from the assumed precondition of full code execution inside a normal web renderer or PPAPI process.
Aside from the new bonuses, it’s worth recapping some details of the existing reward structure that aren’t as widely known:
Our reward program covers vulnerabilities in Adobe Flash as well as other well-known software such as the Linux kernel, various open-source libraries and daemons, X windows, etc.
Our base reward is $2,000 for well-reported UXSS bugs, covering both the Chromium browser and also Adobe Flash. (With the new reward bonus for exploitability, UXSS rewards will likely become $4,000.)
Our reward program already includes a bonus of $500 to $1,000 when the reporter becomes a more involved Chromium community member and provides a peer-reviewed patch.
We have always considered rewards for regressions affecting our Beta or Dev channel releases. It’s a big success to fix security regressions before they ship to the Stable channel.
To illustrate how the new reward bonuses will work, we’re retroactively applying the bonuses to some older, memorable bugs:
$1,000
to Atte Kettunen of OUSPG for
bug 104529
(new total: $2,000). We believe that our PDF component is one of the more secure (C++) implementations of PDF, hence the $1,000 top-up.
$3,000
to Jüri Aedla for
bug 107128
(new total: $4,000). There is a $1,000 bonus because this bug affects many projects via core libxml parsing, and we added a $2,000 bonus for exploitability: this is a heap-based buffer overflow involving user-controlled data with a user-controlled length.
We’re more excited than ever to work with the community and
reward their efforts
.
Posted by Chris Evans, Software Engineer
The evolution of Chrome packaged apps
Thursday, August 9, 2012
Just over a month ago, at Google I/O,
we announced
significant changes to Chrome’s packaged application platform. These changes are intended to allow apps to break out of the browser, work offline by default, and enable richer, more immersive experiences.
Check out our overview video for a quick intro to the new platform.
With the latest version of Chrome in the
developer channel
, you can build, load, debug and test your apps without command-line flags, although you may need to enable experimental APIs in some cases. Because we’re still in developer preview mode, the
Chrome Web Store
doesn’t yet accept uploads of these new packaged apps. We’ll enable web store support later this year, and when we flip that switch, users will be able to discover and download your apps directly from the store.
In order to get started building apps, visit our developer documentation at
developer.chrome.com/apps
and check out our growing list of
sample applications
on Github (thanks for the pull requests; keep them coming). If you’d like to reach us while you’re building apps, you can join us on the #chromium-apps Freenode IRC channel, join the
chromium-apps
group or
report an issue
.
We’re also starting a regular weekly hangout every Tuesday at 9:30am (Pacific Time). Our first one will take place on Tuesday, August 14th. You can add a
reminder to your calendar
and then tune in at
Google Developers Live
. And be sure to add
+Google Chrome Developers
to your circles to keep up on the latest from the Chrome team.
Posted by Mike Tsao, Evolved Software Engineer
The road to safer, more stable, and flashier Flash
Wednesday, August 8, 2012
A little more than two years ago, engineers on the Chrome team began a very ambitious project. In coordination with Adobe, we started porting Flash from the aging NPAPI architecture to our sandboxed PPAPI platform. With
last week’s Chrome Stable release
, we were finally able to ship PPAPI Flash to all Windows Chrome users, so they can now experience dramatically improved security and stability as well as improved performance down the line.
To appreciate just what a big step forward this is, it helps to understand a bit more about the history and architecture of
NPAPI plug-ins
. At its core, NPAPI is a thin layer of glue between the web browser and a native application. In the early days of the Web this provided a tremendous advantage, because it allowed third-party plug-ins to evolve rapidly and implement new capabilities, moving the whole web forward.
Unfortunately, as the web evolved, the past benefits of NPAPI became liabilities. The thinness allowed legacy browser and OS behavior to bleed through and crystallize to the point that it hamstrung future improvements. As browsers add compelling features like sandboxing, GPU acceleration, and a multi-process architecture, the legacy of NPAPI severely impedes or outright prevents us from extending those improvements to any pages with plug-in content.
By porting Flash to PPAPI we’ve been able to achieve what was previously impossible with NPAPI for the
99.9% of Chrome users that rely on Flash
. Windows Flash is now inside a sandbox that’s as strong as Chrome’s native sandbox, and dramatically more robust than anything else available. And for the first time ever, Windows XP users (specifically, over 100 million Chrome users) have a sandboxed Flash—which is critical given the absence of OS support for security features like
ASLR
and
integrity levels
.
Beyond the security benefits, PPAPI has allowed us to move plug-ins forward in numerous other ways. By eliminating the complexity and legacy code associated with NPAPI, we’ve reduced Flash crashes by about 20%. We can also composite Flash content on the GPU, allowing faster rendering and smooth scrolling (with more improvements to come). And because PPAPI doesn’t let the OS bleed through, it’s the only way to use all Flash features on any site in Windows 8 Metro mode.
Moving forward, we’re finishing off the PPAPI Flash port for Mac OS X and hope to ship it soon. And Linux users have already been benefiting from PPAPI Flash since Chrome 20, along with Chrome OS users who have been running it for almost a year. Soon all Chrome users will have access to the improved security, stability, and performance of PPAPI Flash.
Posted by Justin Schuh, Software Engineer and Boring Security Guy
Ending mixed scripting vulnerabilities
Friday, August 3, 2012
Last year, we posted on the Google Online Security Blog about our desire to
end mixed scripting vulnerabilities
. A “mixed scripting” vulnerability affects HTTPS websites that are improperly implemented; these vulnerabilities are serious because they eliminate most of the security protections afforded by HTTPS. All web browsers have historically taken it upon themselves to try and work around these bugs by informing or protecting users in some way.
With the recent release of Chrome 21, we’ve taken several steps forward:
We continue to protect end users by blocking mixed scripting conditions by default, but we now do it in a way that is less intrusive. This change minimizes “security dialog fatigue” and reduces the likelihood that users will expose themselves to risk by clicking through the warning.
We’ve improved resistance to so-called “
clickjacking
” attacks. Electing to run any mixed script is now a two-click process.
We now silently block mixed scripting conditions for websites that opt in to the
HSTS security standard
. This is the strongest default protection available.
If you visit a non-HSTS web site with a mixed scripting condition, a new shield icon in the omnibox (to the right, next to the star) indicates that Chrome’s protection has kicked in:
You can click on the shield to see the option to run the mixed script, but we don’t recommend it. Instead, if you see the shield icon, we recommend contacting the website owners to make sure they know they may have a security vulnerability.
It has been an interesting journey to get to this point. For about a year, we blocked mixed scripting by default on Chrome’s Dev and Beta channel releases. Rolling out the block to Stable was more challenging because of widespread mixed scripting across the web. To move forward, we turned blocking on for certain web sites, starting with
google.com
. Later, we reached out to and then collaborated with
twitter.com
and
facebook.com
to opt them into blocking, too. All these websites hold themselves to a high standard of security, so this approach worked well. We later took the additional step of
opting in sites to mixed script blocking
for any site using the HSTS standard.
We bit the bullet and let full mixed script blocking for all sites hit Stable back in Chrome 19. Predictably, we uncovered a range of buggy web sites, and some users were confused about the “infobar” warning displayed by the older versions of Chrome:
Fortunately—and no doubt driven by the high visibility of this warning—some prominently affected websites were able to deploy quick fixes to resolve their mixed scripting vulnerabilities. This work aligns with one of our
Core Security Principles
: Make the web safer for everyone. Unfortunately, the warning confused some users, which conflicts with another principle: Don’t get in the way. (We’re sorry for any temporary disruption.)
With Chrome 21, we believe we’ve achieved a good balance between top-flight protection for end users, a pleasant UI experience, and notifications that help buggy websites improve their security.
Posted by Chris Evans and Tom Sepez, Software Engineers
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