Security Blog
The latest news and insights from Google on security and safety on the Internet
Gmail account security in Iran
September 8, 2011
Posted by Eric Grosse, VP Security Engineering
We
learned last week
that the compromise of a Dutch company involved with verifying the authenticity of websites could have put the Internet communications of many Iranians at risk, including their Gmail. While Google’s internal systems were not compromised, we are directly contacting possibly affected users and providing similar information below because our top priority is to protect the privacy and security of our users.
While users of the Chrome browser were protected from this threat, we advise all users in Iran to take concrete steps to secure their accounts:
Change your password. You may have already been asked to change your password when you signed in to your Google Account. If not, you can change it
here
.
Verify your account recovery options. Secondary email addresses, phone numbers, and other information can help you regain access to your account if you lose your password. Check to be sure your recovery options are correct and up to date
here
.
Check the websites and applications that are allowed to access your account, and revoke any that are unfamiliar
here
.
Check your Gmail settings for suspicious
forwarding addresses
or
delegated accounts
.
Pay careful attention to
warnings that appear
in your web browser and don’t click past them.
For more ways to secure your account, you can visit
http://www.google.com/help/security
. If you believe your account has been compromised, you can start the recovery process
here
.
An update on attempted man-in-the-middle attacks
August 29, 2011
Posted by Heather Adkins, Information Security Manager
Today we received reports of attempted SSL man-in-the-middle (MITM) attacks against Google users, whereby someone tried to get between them and encrypted Google services. The people affected were primarily located in Iran. The attacker used a fraudulent SSL certificate issued by DigiNotar, a root certificate authority that should not issue certificates for Google (and has since revoked it).
Google Chrome users were protected from this attack because Chrome was able to
detect
the fraudulent certificate.
To further protect the safety and privacy of our users, we plan to disable the DigiNotar certificate authority in Chrome while investigations continue. Mozilla also
moved quickly
to protect its users. This means that Chrome and Firefox users will receive alerts if they try to visit websites that use DigiNotar certificates. Microsoft also has
taken prompt action
.
To help deter unwanted surveillance, we recommend that users, especially those in Iran, keep their web browsers and operating systems up to date and pay attention to web browser security warnings.
Update
Aug 30:
Added information about Microsoft's response.
Update
Sept 3:
Our top priority is to protect the privacy and security of our users. Based on the findings and decision of the Dutch government, as well as conversations with other browser makers, we have decided to reject all of the Certificate Authorities operated by DigiNotar. We encourage DigiNotar to provide a complete analysis of the situation.
Four Years of Web Malware
August 17, 2011
Posted by Lucas Ballard and Niels Provos, Google Security Team
Google’s Safe Browsing initiative has been protecting users from web pages that install malware for over five years now. Each day we show around 3 million malware warnings to over four hundred million users whose browsers implement the Safe Browsing API. Like other service providers, we are engaged in an arms race with malware distributors. Over time, we have adapted our original system to incorporate new detection algorithms that allow us to keep pace. We recently completed an analysis of four years of data that explores the evasive techniques that malware distributors employ. We compiled the results in a technical report, entitled “
Trends in Circumventing Web-Malware Detection
.”
Below are a few of the research highlights, but we recommend reviewing the
full report
for details on our methodology and measurements. The analysis covers approximately 160 million web pages hosted on approximately 8 million sites.
Social Engineering
Social engineering is a malware distribution mechanism that relies on tricking a user into installing malware. Typically, the malware is disguised as an anti-virus product or browser plugin. Social engineering has increased in frequency significantly and is still rising. However, it’s important to keep this growth in perspective — sites that rely on social engineering comprise only 2% of all sites that distribute malware.
Number of sites distributing Social Engineering Malware and Exploits over time
Drive-by Download Exploit Trends
Far more common than social engineering, malicious pages install malware after exploiting a vulnerability in the browser or a plugin. This type of infection is often called a drive-by download. Our analysis of which vulnerabilities are actively being exploited over time shows that adversaries quickly switch to new and more reliable exploits to help avoid detection. The graph below shows the ratio of exploits targeting a vulnerability in one CVE to all exploits over time. Most vulnerabilities are exploited only for a short period of time until new vulnerabilities become available. A prominent exception is the MDAC vulnerability which is present in most exploit kits.
Prevalence of exploits targeting specific CVEs over time
Increase in IP Cloaking
Malware distributors are increasingly relying upon ‘cloaking’ as a technique to evade detection. The concept behind cloaking is simple: serve benign content to detection systems, but serve malicious content to normal web page visitors. Over the years, we have seen more malicious sites engaging in IP cloaking. To bypass the cloaking defense, we run our scanners in different ways to mimic regular user traffic.
Number of sites practicing IP Cloaking over time
New Detection Capabilities
Our report analyzed four years of data to uncover trends in malware distribution on the web, and it demonstrates the ongoing tension between malware distributors and malware detectors. To help protect Internet users, even those who don’t use Google, we have updated the Safe Browsing infrastructure over the years to incorporate many state-of-the-art malware detection technologies. We hope the findings outlined in this report will help other researchers in this area and raise awareness of some of the current challenges.
Fuzzing at scale
August 12, 2011
Posted by Chris Evans, Matt Moore and Tavis Ormandy, Google Security Team
One of the exciting things about working on security at Google is that you have a lot of compute horsepower available if you need it. This is very useful if you’re looking to
fuzz
something, and especially if you’re going to use modern fuzzing techniques.
Using these techniques and large amounts of compute power, we’ve found hundreds of bugs in our own code, including Chrome components such as WebKit and the PDF viewer. We recently decided to apply the same techniques to fuzz Adobe’s Flash Player, which we include with Chrome in partnership with Adobe.
A good overview of some modern techniques can be read
in this presentation
. For the purposes of fuzzing Flash, we mainly relied on “corpus distillation”. This is a technique whereby you locate a large number of sample files for the format at hand (SWF in this case). You then see which areas of code are reached by each of the sample files. Finally, you run an algorithm to generate a minimal set of sample files that achieves the code coverage of the full set. This calculated set of files is a great basis for fuzzing: a manageable number of files that exercise lots of unusual code paths.
What does corpus distillation look like at Google scale? Turns out we have a large index of the web, so we cranked through 20 terabytes of SWF file downloads followed by 1 week of run time on 2,000 CPU cores to calculate the minimal set of about 20,000 files. Finally, those same 2,000 cores plus 3 more weeks of runtime were put to good work mutating the files in the minimal set (bitflipping, etc.) and generating crash cases. These crash cases included an interesting range of vulnerability categories, including buffer overflows, integer overflows, use-after-frees and object type confusions.
The initial run of the ongoing effort resulted in about 400 unique crash signatures, which were logged as 106 individual security bugs following Adobe's initial triage. As these bugs were resolved, many were identified as duplicates that weren't caught during the initial triage. A unique crash signature does not always indicate a unique bug. Since Adobe has access to symbols and sources, they were able to group similar crashes to perform root cause analysis reducing the actual number of changes to the code. No analysis was performed to determine how many of the identified crashes were actually exploitable. However, each crash was treated as though it were potentially exploitable and addressed by Adobe. In the final analysis, the Flash Player update Adobe shipped earlier this week contained about 80 code changes to fix these bugs.
Commandeering massive resource to improve security is rewarding on its own, but the real highlight of this exercise has been Adobe’s response. The
Flash patch
earlier this week fixes these bugs and incorporates UIPI protections for the Flash Player sandbox in Chrome which Justin Schuh contributed assistance on developing. Fixing
so many issues
in such a short time frame shows a real commitment to security from Adobe, for which we are grateful.
2-step verification: stay safe around the world in 40 languages
July 28, 2011
Posted by Nishit Shah, Product Manager, Google Security
(Cross-posted from the
Official Google Blog
)
Earlier this year, we
introduced
a security feature called
2-step verification
that helps protect your Google Account from threats like password compromise and identity theft. By entering a one-time verification code from your phone after you type your password, you can make it much tougher for an unauthorized person to gain access to your account.
People have told us how much they like the feature, which is why we're thrilled to offer 2-step verification in 40 languages and in more than 150 countries. There’s never been a better time to set it up: Examples in the news of password theft and data breaches constantly remind us to stay on our toes and take advantage of tools to properly secure our valuable online information. Email, social networking and other online accounts still get compromised today, but 2-step verification cuts those risks significantly.
We recommend investing some time in keeping your information safe by watching our
2-step verification video
to learn how to quickly increase your Google Account’s resistance to common problems like reused passwords and
malware and phishing scams
. Wherever you are in the world,
sign up for 2-step verification
and help keep yourself one step ahead of the bad guys.
To learn more about online safety tips and resources, visit our ongoing security
blog series
, and review a couple of simple
tips and tricks
for online security. Also, watch our video about
five easy ways
to help you stay safe and secure as you browse.
Update
on 12/1/11
: We recently made 2-step verification available for users in even more places, including Iran, Japan, Liberia, Myanmar (Burma), Sudan and Syria. This enhanced security feature for Google Accounts is now available in more than 175 countries.
Using data to protect people from malware
July 19, 2011
Posted by Damian Menscher, Security Engineer
(Cross-posted from the
Official Google Blog
)
The Internet brings remarkable benefits to society. Unfortunately, some people use it for harm and their own gain at the expense of others. We believe in the power of the web and information, and we work every day to detect potential abuse of our services and ward off attacks.
As we work to protect our users and their information, we sometimes discover unusual patterns of activity. Recently, we found some unusual search traffic while performing routine maintenance on one of our data centers. After collaborating with security engineers at several companies that were sending this modified traffic, we determined that the computers exhibiting this behavior were infected with a particular strain of malicious software, or “malware.” As a result of this discovery, today some people will see a prominent notification at the top of their Google web search results:
This particular malware causes infected computers to send traffic to Google through a small number of intermediary servers called “proxies.” We hope that by taking steps to notify users whose traffic is coming through these proxies, we can help them update their antivirus software and remove the infections.
We hope to use the knowledge we’ve gathered to assist as many people as possible. In case our notice doesn’t reach everyone directly, you can run a system scan on your computer yourself by following the steps in our
Help Center article
.
Updated July 20, 2011:
We've seen a few common questions we thought we'd address here:
The malware appears to have gotten onto users' computers from one of roughly a hundred variants of fake antivirus, or "fake AV" software that has been in circulation for a while. We aren't aware of a common name for the malware.
We believe a couple million machines are affected by this malware.
We've heard from a number of you that you're thinking about the potential for an attacker to copy our notice and attempt to point users to a dangerous site instead. It's a good security practice to be cautious about the links you click, so the spirit of those comments is spot-on. We thought about this, too, which is why the notice appears only at the top of our search results page. Falsifying the message on this page would require prior compromise of that computer, so the notice is not a risk to additional users.
In the meantime, we've been able to successfully warn hundreds of thousands of users that their computer is infected. These are people who otherwise may never have known.
Introducing DOM Snitch, our passive in-the-browser reconnaissance tool
June 21, 2011
Posted by Radoslav Vasilev, Security Test Engineer
(Cross-posted from the
Google Testing Blog
)
Every day modern web applications are becoming increasingly sophisticated, and as their complexity grows so does their attack surface. Previously we introduced open source tools such as
Skipfish
and
Ratproxy
to assist developers in understanding and securing these applications.
As existing tools focus mostly on testingserver-side code, today we are happy to introduce
DOM Snitch
— an experimental* Chrome extension that enables developers and testers to identify insecure practices commonly found in client-side code. To do this, we have adopted
several approaches
to intercepting JavaScript calls to key and potentially dangerous browser infrastructure such as document.write or HTMLElement.innerHTML (
among others
). Once a JavaScript call has been intercepted, DOM Snitch records the document URL and a complete stack trace that will help assess if the intercepted call can lead to cross-site scripting, mixed content, insecure modifications to the
same-origin policy for DOM access
, or other client-side issues.
Here are the benefits of DOM Snitch:
Real-time:
Developers can observe DOM modifications as they happen inside the browser without the need to step through JavaScript code with a debugger or pause the execution of their application.
Easy to use:
With built-in
security heuristics
and nested views, both advanced and less experienced developers and testers can quickly spot areas of the application being tested that need more attention.
Easier collaboration:
Enables developers to easily export and share captured DOM modifications while troubleshooting an issue with their peers.
DOM Snitch is intended for use by developers, testers, and security researchers alike.
Click here
to download DOM Snitch. To read the documentation, please visit
this page
.
*Developers and testers should be aware that DOM Snitch is currently experimental. We do not guarantee that it will work flawlessly for all web applications. More details on known issues can be found
here
or in the project’s
issues tracker
.
Protecting users from malware hosted on bulk subdomain services
June 17, 2011
Posted by Oliver Fisher, Google Anti-Malware Team
Over the past few months, Google’s systems have detected a number of bulk subdomain providers becoming targets of abuse by malware distributors. Bulk subdomain providers register a domain name, like example.com, and then sell subdomains of this domain name, like subdomain.example.com. Subdomains are often registered by the thousands at one time and are used to distribute malware and fake anti-virus products on the web. In some cases our malware scanners have found more than 50,000 malware domains from a single bulk provider.
Google’s automated malware scanning systems detect sites that distribute malware. To help protect users we recently modified those systems to identify bulk subdomain services which are being abused. In some severe cases our systems may now flag the whole bulk domain.
We offer many services to webmasters to help them fight abuse, such as:
Webmaster Tools
lets webmasters find examples of URLs under their domains that may be distributing malware.
Google Safe Browsing Alerts for Network Administrators
allows owners of Autonomous Systems to get notifications for hosts that are involved in malware delivery.
If you are the owner of a website that is hosted in a bulk subdomain service, please consider contacting your bulk subdomain provider if Google SafeBrowsing shows a warning for your site. The top-level bulk subdomain may be a target of abuse. Bulk subdomain service providers may use Google’s tools to help identify and disable abusive subdomains and accounts.
Trying to end mixed scripting vulnerabilities
June 16, 2011
Posted by Chris Evans and Tom Sepez, Google Chrome Security Team
A “mixed sc
ripting” vulnerability is caused when a page served over HTTPS loads a script, CSS, or plug-in resource over HTTP. A man-in-the-middle attacker (such as someone on the same wireless network) can typically intercept the HTTP resource
load and gain full access to the website loading the resource. It’s often as bad as if the web page hadn’t used HTTPS at all.
A less severe but similar problem -- let’s call it a “mixed display” vulnerability -- is caused when a page served over HTTPS loads an image, iFrame, or font over HTTP. A man-in-the-middle attacker can again intercept the HTTP resource load but normally can only affect the appearance of the page.
Browsers have long used different indicators, modal dialogs, block options or even click-throughs to indicate these conditions to users. If a page on your website has a mixed scripting issue, Chromium will currently indicate it like this in the URL bar:
And for a mixed display issue:
If any of the HTTPS pages on your website show the cross-out red https, there are good reasons to investigate promptly:
Your website won’t work as well in other modern browsers (such as IE9 or FF4) due to click-throughs and ugly modal dialogs.
You may have a security vulnerability that could compromise the entire HTTPS connection.
As of the first Chromium 14 canary release (14.0.785.0), we are trialing blocking mixed scripting conditions by default. We’ll be carefully listening to feedback; please leave it on
this Chromium bug
.
We also added an infobar that shows when a script is being blocked:
As a user, you can choose to reload the website without the block applied. Ideally, in the longer term, the infobar will not have the option for the user to bypass it. Our experience shows that some subset of users will attempt to “click through” even the scariest of warnings -- despite the hazards that can follow.
Tools that can help website owners
If Chromium’s UI shows any mixed content issues on your site, you can try to use a couple of our developer tools to locate the problem. A useful message is typically logged to the JavaScript console (Menu -> Tools -> JavaScript Console):
You can also reload the page with the “Network” tab active and look for requests that were issued over the http:// protocol. It’s worth noting that the entire origin is poisoned when mixed scripting occurs in it, so you’ll want to look at the console for all tabs that reference the indicated origin. To clear the error, all tabs that reference the poisoned origin need to be closed. For particularly tough cases where it’s not clear how the origin became poisoned, you can also
enable debugging to the command-line console
to see the relevant warning message.
The latest Chromium 13 dev channel build (13.0.782.10) has a command line flag:
--no-running-insecure-content
. We recommend that website owners and advanced users run with this flag, so we can all help mop up errant sites. (We also have the flag
--no-displaying-insecure-content
for the less serious class of mixed content issues; there are no plans to block this by default in Chromium 14).
The Chromium 14 release will come with an inverse flag: --allow-running-insecure-content, as a convenience for users and admins who have internal applications without immediate fixes for these errors.
Thanks for helping us push website security forward as a community. Until this class of bug is stamped out, Chromium has your back.
Safe Browsing Protocol v2 Transition
May 26, 2011
Posted by Ian Fette, Google Security Team
Last year, we released
version 2
of the Safe Browsing API, along with a
reference implementation
in Python. This version provides more efficient updates compared to version 1, giving clients the most useful (freshest) data first. The new version uses significantly less bandwidth, and also allows us to serve data that covers more URLs than previously possible. Browsers including Chrome and Firefox have already migrated to version 2, and we are confident that the new version works well and delivers significant benefits compared to the previous version.
We are now planning to discontinue version 1 of the protocol to help us better focus our efforts and resources. On December 1, 2011, we will stop supporting version 1 and will take the service down shortly thereafter. If you are currently using version 1 of the protocol, we encourage you to migrate as soon as possible to the new version. In addition to the
documentation
and
reference implementation
, there’s a
Google Group
dedicated to the API where you may be able to get additional advice or ask questions as you prepare to transition. Those of you who who have already migrated to version 2 will not be affected and do not need to take any further action.
If you are looking to migrate from the version 1 API and are worried about the complexity of the version 2 API, we now have a
lookup service
that you can use in lieu of version 2 of the Safe Browsing Protocol if your usage is relatively low. The lookup service is a RESTful service that lets you send a URL or set of URLs to Google and receive a reply indicating the state of those URLs. You can use this API if you check fewer than 100,000 URLs per day and don’t mind waiting on a network roundtrip. This process may be simpler to use than version 2 of the Safe Browsing Protocol, but it is not supported for users who will generate excessive load (meaning that your software, either your servers or deployed clients, will collectively generate over 100,000 requests to Google in a 24-hour period).
If you are currently using version 1 of the Safe Browsing Protocol, please update to either the Safe Browsing Protocol version 2, or the lookup service, before December 1, 2011. If you have any questions, feel free to check out the Google Safe Browsing API
discussion list
.
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