Multiple features that ensure security and scalability
Inside physical boundaries controlled by or on behalf of Google, all scheduled production workloads are initialized with a certificate that asserts their identity. These credentials are securely delivered to the workloads. When a workload is involved in an ALTS handshake, it verifies the remote peer identity and certificate. To further increase security, all Google certificates have a relatively short lifespan.
ALTS has a flexible trust model that works for different types of entities on the network. Entities can be physical machines, containerized workloads, and even human users to whom certificates can be provisioned.
ALTS provides a handshake protocol, which is a Diffie-Hellman (DH) based authenticated key exchange protocol that Google developed and implemented. At the end of a handshake, ALTS provides applications with an authenticated remote peer identity, which can be used to enforce fine-grained authorization policies at the application layer.
ALTS ensures the integrity of Google traffic is protected, and encrypted as needed.
After a handshake is complete and the client and server negotiate the necessary shared secrets, ALTS secures RPC traffic by forcing integrity, and optional encryption, using the negotiated shared secrets. We support multiple protocols for integrity guarantees, e.g., AES-GMAC and AES-VMAC with 128-bit keys. Whenever traffic leaves a physical boundary controlled by or on behalf of Google, e.g., in transit over WAN between datacenters, all protocols are upgraded automatically to provide encryption as well as integrity guarantees. In this case, we use the AES-GCM and AES-VCM protocols with 128-bit keys.
More details on how Google data encryption is performed are available in another whitepaper we are releasing today, “Encryption in Transit in Google Cloud.”
In summary, ALTS is widely used in Google’s infrastructure to provide service-to-service authentication and integrity, with optional encryption for all Google RPC traffic. For more information about ALTS, please read our whitepaper, “Application Layer Transport Security.”
To protect Android devices and users, we used Google Play Protect to disable Tizi-infected apps on affected devices and have notified users of all known affected devices. The developers' accounts have been suspended from Play.
The Google Play Protect team also used information and signals from the Tizi apps to update Google's on-device security services and the systems that search for PHAs. These enhancements have been enabled for all users of our security services and increases coverage for Google Play users and the rest of the Android ecosystem.
Additionally, there is more technical information below to help the security industry in our collective work against PHAs.
What do I need to do?
Through our investigation, we identified around 1,300 devices affected by Tizi. To reduce the chance of your device being affected by PHAs and other threats, we recommend these 5 basic steps:
Check permissions: Be cautious with apps that request unreasonable permissions. For example, a flashlight app shouldn't need access to send SMS messages.
Enable a secure lock screen: Pick a PIN, pattern, or password that is easy for you to remember and hard for others to guess.
Update your device: Keep your device up-to-date with the latest security patches. Tizi exploited older and publicly known security vulnerabilities, so devices that have up-to-date security patches are less exposed to this kind of attack.
Locate your device: Practice finding your device, because you are far more likely to lose your device than install a PHA.
How does Tizi work?
The Google Play Protect team had previously classified some samples as spyware or backdoor PHAs without connecting them as a family. The early Tizi variants didn't have rooting capabilities or obfuscation, but later variants did.
After gaining root, Tizi steals sensitive data from popular social media apps like Facebook, Twitter, WhatsApp, Viber, Skype, LinkedIn, and Telegram. It usually first contacts its command-and-control servers by sending an SMS with the device's GPS coordinates to a specific number. Subsequent command-and-control communications are normally performed over regular HTTPS, though in some specific versions, Tizi uses the MQTT messaging protocol with a custom server. The backdoor contains various capabilities common to commercial spyware, such as recording calls from WhatsApp, Viber, and Skype; sending and receiving SMS messages; and accessing calendar events, call log, contacts, photos, Wi-Fi encryption keys, and a list of all installed apps. Tizi apps can also record ambient audio and take pictures without displaying the image on the device's screen.
Tizi can root the device by exploiting one of the following local vulnerabilities:
CVE-2012-4220
CVE-2013-2596
CVE-2013-2597
CVE-2013-2595
CVE-2013-2094
CVE-2013-6282
CVE-2014-3153
CVE-2015-3636
CVE-2015-1805
Most of these vulnerabilities target older chipsets, devices, and Android versions. All of the listed vulnerabilities are fixed on devices with a security patch level of April 2016 or later, and most of them were patched considerably prior to this date. Devices with this patch level or later are far less exposed to Tizi's capabilities. If a Tizi app is unable to take control of a device because the vulnerabilities it tries to use are are all patched, it will still attempt to perform some actions through the high level of permissions it asks the user to grant to it, mainly around reading and sending SMS messages and monitoring, redirecting, and preventing outgoing phone calls.
Samples uploaded to VirusTotal
To encourage further research in the security community, here are some sample applications embedding Tizi that were already on VirusTotal.
Tamper-resistant hardware comes in the form of a discrete chip separate from the System on a Chip (SoC). It includes its own flash, RAM, and other resources inside a single package, so it can fully control its own execution. It can also detect and defend against outside attempts to physically tamper with it.
In particular:
Because it has its own dedicated RAM, it’s robust against many side-channel information leakage attacks, such as those described in the TruSpy cache side-channel paper.
Because it has its own dedicated flash, it’s harder to interfere with its ability to store state persistently.
It loads its operating system and software directly from internal ROM and flash, and it controls all updates to it, so attackers can’t directly tamper with its software to inject malicious code.
Tamper-resistant hardware is resilient against many physical fault injection techniques including attempts to run outside normal operating conditions, such as wrong voltage, wrong clock speed, or wrong temperature. This is standardized in specifications such as the SmartCard IC Platform Protection Profile, and tamper-resistant hardware is often certified to these standards.
Tamper-resistant hardware is usually housed in a package that is resistant to physical penetration and designed to resist side channel attacks, including power analysis, timing analysis, and electromagnetic sniffing, such as described in the SoC it to EM paper.
Security module in Pixel 2
The new Google Pixel 2 ships with a security module built using tamper-resistant hardware that protects your lock screen and your data against many sophisticated hardware attacks.
In addition to all the benefits already mentioned, the security module in Pixel 2 also helps protect you against software-only attacks:
Because it performs very few functions, it has a super small attack surface.
With passcode verification happening in the security module, even in the event of a full compromise elsewhere, the attacker cannot derive your disk encryption key without compromising the security module first.
The security module is designed so that nobody, including Google, can update the passcode verification logic to a weakened version without knowing your passcode first.
Summary
Just like many other Google products, such as Chromebooks and Cloud, Android and Pixel are investing in additional hardware protections to make your device more secure. With the new Google Pixel 2, your data is safer against an entire class of sophisticated hardware attacks.
Our research tracked several black markets that traded third-party password breaches, as well as 25,000 blackhat tools used for phishing and keylogging. In total, these sources helped us identify 788,000 credentials stolen via keyloggers, 12 million credentials stolen via phishing, and 3.3 billion credentials exposed by third-party breaches.
While our study focused on Google, these password stealing tactics pose a risk to all account-based online services. In the case of third-party data breaches, 12% of the exposed records included a Gmail address serving as a username and a password; of those passwords, 7% were valid due to reuse. When it comes to phishing and keyloggers, attackers frequently target Google accounts to varying success: 12-25% of attacks yield a valid password.
However, because a password alone is rarely sufficient for gaining access to a Google account, increasingly sophisticated attackers also try to collect sensitive data that we may request when verifying an account holder’s identity. We found 82% of blackhat phishing tools and 74% of keyloggers attempted to collect a user’s IP address and location, while another 18% of tools collected phone numbers and device make and model.
By ranking the relative risk to users, we found that phishing posed the greatest threat, followed by keyloggers, and finally third-party breaches.
Protecting our users from account takeover
Our findings were clear: enterprising hijackers are constantly searching for, and are able to find, billions of different platforms’ usernames and passwords on black markets. While we have already applied these insights to our existing protections, our findings are yet another reminder that we must continuously evolve our defenses in order to stay ahead of these bad actors and keep users safe.
For many years, we’ve applied a ‘defense in-depth’ approach to security—a layered series of constantly improving protections that automatically prevent, detect, and mitigate threats to keep your account safe.
Detection
We monitor every login attempt to your account for suspicious activity. When there is a sign-in attempt from a device you’ve never used, or a location you don’t commonly access your account from, we’ll require additional information before granting access to your account. For example, if you sign in from a new laptop and you have a phone associated with you account, you will see a prompt—we’re calling these dynamic verification challenges—like this:
This challenge provides two-factor authentication on all suspicious logins, while mitigating the risk of account lockout.
Mitigation
Finally, we regularly scan activity across Google’s suite of products for suspicious actions performed by hijackers and when we find any, we lock down the affected accounts to prevent any further damage as quickly as possible. We prevent or undo actions we attribute to account takeover, notify the affected user, and help them change their password and re-secure their account into a healthy state.
What you can do
There are some simple steps you can take that make these defenses even stronger. Visit our Security Checkup to make sure you have recovery information associated with your account, like a phone number. Allow Chrome to automatically generate passwords for your accounts and save them via Smart Lock. We’re constantly working to improve these tools, and our automatic protections, to keep your data safe.
CVE-2017-14491 is a DNS-based vulnerability that affects both directly exposed and internal network setups. Although the latest git version only allows a 2-byte overflow, this could be exploited based on previous research. Before version 2.76 and this commit the overflow is unrestricted.
==1159==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x62200001dd0b at pc 0x0000005105e7 bp 0x7fff6165b9b0 sp0x7fff6165b9a8
WRITE of size 1 at 0x62200001dd0b thread T0
#0 0x5105e6 in add_resource_record
/test/dnsmasq/src/rfc1035.c:1141:7
#1 0x5127c8 in answer_request /test/dnsmasq/src/rfc1035.c:1428:11
#2 0x534578 in receive_query /test/dnsmasq/src/forward.c:1439:11
#3 0x548486 in check_dns_listeners
/test/dnsmasq/src/dnsmasq.c:1565:2
#4 0x5448b6 in main /test/dnsmasq/src/dnsmasq.c:1044:7
#5 0x7fdf4b3972b0 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x202b0)
#6 0x41cbe9 in _start (/test/dnsmasq/src/dnsmasq+0x41cbe9)
CVE-2017-14493 is a trivial-to-exploit DHCP-based, stack-based buffer overflow vulnerability. In combination with CVE-2017-14494 acting as an info leak, an attacker could bypass ASLR and gain remote code execution.
dnsmasq[15714]: segfault at 1337deadbeef ip 00001337deadbeef sp 00007fff1b66fd10 error 14 in libnss_files-2.24.so[7f7cfbacb000+a000]
Android is affected by CVE-2017-14496 when the attacker is local or tethered directly to the device—the service itself is sandboxed so the risk is reduced. Android partners received patches on 5 September 2017 and devices with a 2017-10-01 security patch level or later address this issue.
Proofs of concept are provided so you can check if you are affected by these issues, and verify any mitigations you may deploy.
We would like to thank the following people for discovering, investigating impact/exploitability and developing PoCs: Felix Wilhelm, Fermin J. Serna, Gabriel Campana, Kevin Hamacher, Ron Bowes and Gynvael Coldwind of the Google Security Team.
Computing has evolved a bit in the last decade, though. Smartphones created a more mobile internet, and now AI is increasingly changing how the world interacts with it. Safe Browsing also had to evolve to effectively protect users.
And it has: In May 2016, we announced that Safe Browsing was protecting more than 2 billion devices from badness on the internet. Today we’re announcing that Safe Browsing has crossed the threshold to 3 billion devices. We’re sharing a bit more about how we got here, and where we’re going.
What is Safe Browsing?
You may not know Safe Browsing by name, since most of the time we’re invisibly protecting you, without getting in the way. But you may have seen a warning like this at some point:
This notification is one of the visible parts of Safe Browsing, a collection of Google technologies that hunt badness—typically websites that deceive users—on the internet. We identify sites that might try to phish you, or sites that install malware or other undesirable software. The systems that make up Safe Browsing work together to identify, analyze and continuously keep Safe Browsing’s knowledge of the harmful parts of the internet up to date.
This protective information that we generate—a curated list of places that are dangerous for people and their devices—is used across many of our products. It helps keep search results safe and keep ads free from badness; it’s integral to Google Play Protect and keeps you safe on Android; and it helps Gmail shield you from malicious messages.
And Safe Browsing doesn’t protect only Google’s products. For many years, Safari and Firefox have protected their users with Safe Browsing as well. If you use an up-to-date version of Chrome, Firefox or Safari, you’re protected by default. Safe Browsing is also used widely by web developers and app developers (including Snapchat), who integrate our protections by checking URLs before they’re presented to their users. Protecting more people with fewer bits
In the days when web browsers were used only on personal computers, we didn’t worry much about the amount of data Safe Browsing sent over the internet to keep your browser current. Mobile devices changed all that: Slow connections, expensive mobile data plans, and scarce battery capacity became important new considerations.
So over the last few years, we’ve rethought how Safe Browsing delivers data. We built new technologies to make its data as compact as possible: We only send the information that’s most protective to a given device, and we make sure this data is compressed as tightly as possible. (All this work benefits desktop browsers, too!)
Safe Browsing in an AI-first world
The internet is at the start of another major shift. Safe Browsing has already been using machine learning for many years to detect much badness of many kinds. We’re continually evaluating and integrating cutting-edge new approaches to improve Safe Browsing.
Protecting all users across all their platforms makes the internet safer for everyone. Wherever the future of the internet takes us, Safe Browsing will be there, continuing to evolve, expand, and protect people wherever they are.
Site Operators using Symantec-issued TLS server certificates issued before June 1, 2016 should replace these certificates. These certificates can be replaced by any currently trusted CA.
~October 24, 2017
Chrome 62 released to Stable, which will add alerting in DevTools when evaluating certificates that will be affected by the Chrome 66 distrust.
December 1, 2017
According to Symantec, DigiCert’s new “Managed Partner Infrastructure” will at this point be capable of full issuance. Any certificates issued by Symantec’s old infrastructure after this point will cease working in a future Chrome update.
From this date forward, Site Operators can obtain TLS server certificates from the new Managed Partner Infrastructure that will continue to be trusted after Chrome 70 (~October 23, 2018).
December 1, 2017 does not mandate any certificate changes, but represents an opportunity for site operators to obtain TLS server certificates that will not be affected by Chrome 70’s distrust of the old infrastructure.
~March 15, 2018
Chrome 66 released to beta, which will remove trust in Symantec-issued certificates with a not-before date prior to June 1, 2016. As of this date Site Operators must be using either a Symantec-issued TLS server certificate issued on or after June 1, 2016 or a currently valid certificate issued from any other trusted CA as of Chrome 66.
Site Operators that obtained a certificate from Symantec’s old infrastructure after June 1, 2016 are unaffected by Chrome 66 but will need to obtain a new certificate by the Chrome 70 dates described below.
~April 17, 2018
Chrome 66 released to Stable.
~September 13, 2018
Chrome 70 released to Beta, which will remove trust in the old Symantec-rooted Infrastructure. This will not affect any certificate chaining to the new Managed Partner Infrastructure, which Symantec has said will be operational by December 1, 2017.
Only TLS server certificates issued by Symantec’s old infrastructure will be affected by this distrust regardless of issuance date.
After we blocked the first set of apps on Google Play, new apps were uploaded with a similar format but had a couple of differences.
The apps changed from ‘backup’ apps to looking like a “cleaner”, “notepad”, “sound recorder”, and “alarm manager” app. The new apps were uploaded within a week of the takedown, showing that the authors have a method of easily changing the branding of the implant apps.
The app changed from downloading an unencrypted stage 2 to including stage 2 as an encrypted blob. The new stage 1 would only decrypt and load the 2nd stage if it received an intent with an AES key and IV.
Despite changing the type of app and the method to download stage 2, we were able to catch the new implant apps soon after upload.
How many devices were affected?
There were fewer than 100 devices that checked into Google Play Protect with the apps listed below. That means the family affected only 0.000007% of Android devices. Since we identified Lipizzan, Google Play Protect removed Lipizzan from affected devices and actively blocks installs on new devices.
