Extending SSL to Google search

Posted by Murali Viswanathan, Product Manager

Google understands the potential risks of browsing the web on an unsecured network, particularly when information is sent over the wire unencrypted — as it is for most major websites today. That’s why we offered SSL support for Gmail back when we launched the product in 2004. Most other webmail providers don’t provide this feature even today. We’ve since added SSL support for Calendar, Docs, Sites, and several other products. Additionally, early this year we made SSL the default setting for all Gmail users.

As we work to provide more support for SSL across our products, today we’re introducing the ability to search with Google over SSL. We still have some testing to do, but you can try out the new encrypted version of Google search at https://www.google.com and read more about it on the Official Google Blog.

Do Know Evil: web application vulnerabilities

Posted by Bruce Leban, Software Engineer

UPDATE July 13: We have changed the name of the codelab application to Gruyere. The codelab is now located at http://google-gruyere.appspot.com.

We want Google employees to have a firm understanding of the threats our services face, as well as how to help protect against those threats. We work toward these goals in a variety of ways, including security training for new engineers, technical presentations about security, and other types of documentation. We also use codelabs — interactive programming tutorials that walk participants through specific programming tasks.

One codelab in particular teaches developers about common types of web application vulnerabilities. In the spirit of the thinking that "it takes a hacker to catch a hacker," the codelab also demonstrates how an attacker could exploit such vulnerabilities.

We're releasing this codelab, entitled "Web Application Exploits and Defenses," today in coordination with Google Code University and Google Labs to help software developers better recognize, fix, and avoid similar flaws in their own applications. The codelab is built around Gruyere, a small yet full-featured microblogging application designed to contain lots of security bugs. The vulnerabilities covered by the lab include cross-site scripting (XSS), cross-site request forgery (XSRF) and cross-site script inclusion (XSSI), as well as client-state manipulation, path traversal and AJAX and configuration vulnerabilities. It also shows how simple bugs can lead to information disclosure, denial-of-service and remote code execution.

The maxim, "given enough eyeballs, all bugs are shallow" is only true if the eyeballs know what to look for. To that end, the security bugs in Gruyere are real bugs — just like those in many other applications. The Gruyere source code is published under a Creative Commons license and is available for use in whitebox hacking exercises or in computer science classes covering security, software engineering or general software development.

To get started, visit http://google-gruyere.appspot.com. An instructor's guide for using the codelab is now available on Google Code University.

The Rise of Fake Anti-Virus

Posted by Niels Provos, Security Team
For years, we have detected malicious content on the web and helped protect users from it. Vulnerabilities in web browsers and popular plugins have resulted in an increased number of users whose systems can be compromised by attacks known as drive-by downloads. Such attacks do not require any user interaction, and they allow the adversary to execute code on a user’s computer without their knowledge. However, even without any vulnerabilities present, clever social engineering attacks can cause an unsuspecting user to unwittingly install malicious code supplied by an attacker on their computer.

One increasingly prevalent threat is the spread of Fake Anti-Virus (Fake AV) products. This malicious software takes advantage of users’ fear that their computer is vulnerable, as well as their desire to take the proper corrective action. Visiting a malicious or compromised web site — or sometimes even viewing a malicious ad — can produce a screen looking something like the following:


At Google, we have been working to help protect users against Fake AV threats on the web since we first discovered them in March 2007. In addition to protections like adding warnings to browsers and search results, we’re also actively engaged in malware research. We conducted an in-depth analysis of the prevalence of Fake AV over the course of the last 13 months, and the research paper containing our findings, “The Nocebo Effect on the Web: An Analysis of Fake AV distribution” is going to be presented at the Workshop on Large-Scale Exploits and Emergent Threats (LEET) in San Jose, CA on April 27th. While we do not want to spoil any surprises, here are a few previews. Our analysis of 240 million web pages over the 13 months of our study uncovered over 11,000 domains involved in Fake AV distribution — or, roughly 15% of the malware domains we detected on the web during that period.

Also, over the last year, the lifespan of domains distributing Fake AV attacks has decreased significantly:


In the meantime, we recommend only running antivirus and antispyware products from trusted companies. Be sure to use the latest versions of this software, and if the scan detects any suspicious programs or applications, remove them immediately.

The chilling effects of malware

Posted by Neel Mehta, Security Team

In January, we discussed a set of highly sophisticated cyber attacks that originated in China and targeted many corporations around the world. We believe that malware is a general threat to the Internet, but it is especially harmful when it is used to suppress opinions of dissent. In that case, the attacks involved surveillance of email accounts belonging to Chinese human rights activists. Perhaps unsurprisingly, these are not the only examples of malicious software being used for political ends. We have gathered information about a separate cyber threat that was less sophisticated but that nonetheless was employed against another community.

This particular malware broadly targeted Vietnamese computer users around the world. The malware infected the computers of potentially tens of thousands of users who downloaded Vietnamese keyboard language software and possibly other legitimate software that was altered to infect users. While the malware itself was not especially sophisticated, it has nonetheless been used for damaging purposes. These infected machines have been used both to spy on their owners as well as participate in distributed denial of service (DDoS) attacks against blogs containing messages of political dissent. Specifically, these attacks have tried to squelch opposition to bauxite mining efforts in Vietnam, an important and emotionally charged issue in the country.

Since some anti-virus vendors have already introduced signatures to help detect this specific malware, we recommend the following actions, particularly if you believe that you may have been exposed to the malware: run regular anti-virus as well as anti-spyware scans from trusted vendors, and be sure to install all web browser and operating system updates to ensure you’re using only the latest versions. New technology like our suspicious account activity alerts in Gmail should also help detect surveillance efforts. At a larger scale, we feel the international community needs to take cybersecurity seriously to help keep free opinion flowing.

Phishing phree

Posted by Colin Whittaker, Anti-Phishing Team

To help protect you from a wide array of Internet scams you may encounter while searching, we analyze millions of webpages daily for phishing behavior. Each year, we find hundreds of thousands of phishing pages and add them to our list that we use to directly warn users of Firefox, Safari, and Chrome via our SafeBrowsing API. How do we find all these phishing pages? We certainly don’t do it by hand!

Instead, we have taught computers to look for certain telltale signs, as we describe in a paper that we recently presented at the 17th Annual Network and Distributed System Security Symposium. In a nutshell, our system looks at many of the same elements of a webpage that you would check to help evaluate whether the page is designed for phishing. If our system determines that a page is being used for phishing, it will automatically produce a warning for all of our users who try to visit that page. This scalable design enables us to review all these potentially “phishy” pages in about a minute each.

What we look for

Our system analyzes a number of webpage features to help make a verdict about whether a site is a phishing site. Starting with a page’s URL, we look to see if there is anything unusual about the host, such as whether the hostname is unusually long or whether the URL uses an IP address to specify the host. We also look to see if the URL contains any phrases like “banking” or “login” that might indicate that the page is trying to steal information.

We don’t just look at the URL, though. After all, a perfectly legitimate site could certainly use words like “banking” or “login.” We collect a snapshot of the page’s content to examine it closely for phishing behavior. For example, we check to see if the page has a password field or whether most of the links point to a common phishing target, as both of these characteristics can be a sign of phishing. Additionally, we pick out some of the most characteristic terms that show up on a page (as defined by their TF-IDF scores), and look for terms like “password” or “PIN number,” which also may indicate that the page is intended for phishing.

We also check the page’s hosting information to find out which networks host the page and where the page’s servers are located geographically. If a site purporting to be an American bank runs its servers in a different country and is hosted on a local residential ISP’s network, we have a strong signal that the site is bad.

Finally, we check the page’s PageRank to see if the page is popular or not, and we check the spam reputation of the page’s domain. We discovered in our research findings that almost all phishing pages are found on domains that almost exclusively send spam. You can observe this trend in the CCDF graph of the spam reputation scores for phishing pages as compared to the graph of other, non-phishing pages.


How we learn to recognize phishing pages

We use a sample of the data that our system generates to train the classifier that lies at the core of our automatic system using a machine learning algorithm. Coming up with good labels (phishing/not phishing) for this data is tricky because we can’t label each of the millions of pages ourselves. Instead, we use our published phishing page list, largely generated by our classifier, to assign labels for the training data.

You might be wondering if this system is going to lead to situations where the classifier makes a mistake, puts that mistake on our list, and then uses the list to learn to make more mistakes. Fortunately, the chain doesn’t make it that far. Our classifier only makes a relatively small number of mistakes, which we can correct manually when you report them to us. Our learning algorithms can handle a few temporary errors in the training labels, and the overall learning process remains stable.

How well does this work?

Of the millions of webpages that our scanners analyze for phishing, we successfully identify 9 out of 10 phishing pages. Our classification system only incorrectly flags a non-phishing site as a phishing site about 1 in 10,000 times, which is significantly better than similar systems. In our experience, these “false positive” sites are usually built to distribute spam or may be involved with other suspicious activity. While phishers are constantly changing their strategies, we find that they do not change them enough to reliably escape our system. Our experiments showed that our classification system remained effective for over a month without retraining.

If you are a webmaster and would like more information about how to keep your site from looking like a phishing site, please check out our post on the Webmaster Central Blog. If you find that your site has been added to our phishing page list ("Reported Web Forgery!") by mistake, please report the error to us.

Detecting suspicious account activity

(Cross-posted from the Gmail Blog)

Posted by Pavni Diwanji, Engineering Director

A few weeks ago, I got an email presumably from a friend stuck in London asking for some money to help him out. It turned out that the email was sent by a scammer who had hijacked my friend's account. By reading his email, the scammer had figured out my friend's whereabouts and was emailing all of his contacts. Here at Google, we work hard to protect Gmail accounts against this kind of abuse. Today we're introducing a new feature to notify you when we detect suspicious login activity on your account.

You may remember that a while back we launched remote sign out and information about recent account activity to help you understand and manage your account usage. This information is still at the bottom of your inbox. Now, if it looks like something unusual is going on with your account, we’ll also alert you by posting a warning message saying, "Warning: We believe your account was last accessed from…" along with the geographic region that we can best associate with the access.


To determine when to display this message, our automated system matches the relevant IP address, logged per the Gmail privacy policy, to a broad geographical location. While we don't have the capability to determine the specific location from which an account is accessed, a login appearing to come from one country and occurring a few hours after a login from another country may trigger an alert.

By clicking on the "Details" link next to the message, you'll see the last account activity window that you're used to, along with the most recent access points.


If you think your account has been compromised, you can change your password from the same window. Or, if you know it was legitimate access (e.g. you were traveling, your husband/wife who accesses the account was also traveling, etc.), you can click "Dismiss" to remove the message.

Keep in mind that these notifications are meant to alert you of suspicious activity but are not a replacement for account security best practices. If you'd like more information on account security, read these tips on keeping your information secure or visit the Google Online Security Blog.

Finally, we know that security is also a top priority for businesses and schools, and we look forward to offering this feature to Google Apps customers once we have gathered and incorporated their feedback.

Meet skipfish, our automated web security scanner

Posted by Michal Zalewski

The safety of the Internet is of paramount importance to Google, and helping web developers build secure, reliable web applications is an important part of the equation. To advance this goal, we have released projects such as ratproxy, a passive security assessment tool; and Browser Security Handbook, a comprehensive guide for web developers. We also worked with the community to improve the security of third-party browsers.

Today, we are happy to announce the availability of skipfish - our free, open source, fully automated, active web application security reconnaissance tool. We think this project is interesting for a few reasons:

• High speed: written in pure C, with highly optimized HTTP handling and a minimal CPU footprint, the tool easily achieves 2000 requests per second with responsive targets.
  
  
• Ease of use: the tool features heuristics to support a variety of quirky web frameworks and mixed-technology sites, with automatic learning capabilities, on-the-fly wordlist creation, and form autocompletion.
  
  
• Cutting-edge security logic: we incorporated high quality, low false positive, differential security checks capable of spotting a range of subtle flaws, including blind injection vectors.
  

As with ratproxy, we feel that skipfish will be a valuable contribution to the information security community, making security assessments significantly more accessible and easier to execute.

To download the scanner, please visit this page; detailed project documentation is available here.