Google is preparing new functionality for Android that will allow apps to retrieve and auto-fill security codes from SMS. Last year Apple introduced a similar feature to iOS and macOS, for which we discovered security risks for online banking, two-factor authentication, and other services. Will Google come up with a better design? In this post, we analyse what we know about this feature so far.
The latest developer beta of Google Play Services (18.7.13 beta) contains code fragments that show a new Android permission to automatically retrieve verification codes from text messages. This feature has not yet been fully implemented, but the available code allows for some analysis and early evaluation for possible security risks, akin to similarrisks we demonstrated in 2018 for the Security Code AutoFill feature in iOS and macOS.
Background
It seems that Google is updating the “Autofill Framework”, introduced with Android 8.0 in 2017, to include the new functionality. Previously, this framework’s sole purpose was to support the autofill functionality of password managers in Android apps and websites. The code fragments of this new feature reveal the names and descriptions of the associated system setting and corresponding runtime permission requests, shown below.
The likely UI of the new setting in Android to enable/disable SMS Code Auto-fill.The likely UI of the new runtime permission request in Android to deny or allow an application’s access to the SMS Code Auto-fill feature.
Inadequate user interface designs in Windows 10 and macOS Mojave can cause accidental data breaches through inconsistent language, insecure default options, and unclear or incomprehensible information. Users could accidentally leak sensitive personal data. Data controllers in companies might be unknowingly non-compliant with the GDPR’s legal obligations for data erasure.
At the upcoming Annual Privacy Forum 2019 in Rome, I will be presenting the results of a recent study conducted with my colleague Mark Warner, exploring the inadequate design of user interfaces (UI) as a contributing factor in accidental data breaches from USB memory sticks. The paper titled “Fight to be Forgotten: Exploring the Efficacy of Data Erasure in Popular Operating Systems” will be published in the conference proceedings at a later date but the accepted version is available now.
Privacy and security risks from decommissioned memory chips
The process of decommissioning memory chips (e.g. USB sticks, hard drives, and memory cards) can create risks for data protection. Researchers have repeatedly found sensitive data on devices they acquired from second-hand markets. Sometimes this data was from the previous owners, other times from third persons. In some cases, highly sensitive data from vulnerable people were found, e.g. Jones et al. found videos of children at a high school in the UK on a second-hand USB stick.
Data found this way had frequently been deleted but not erased, creating the risk that any tech-savvy future owner could access it using legally available, free to download software (e.g., FTK Imager Lite 3.4.3.3). Findings from these studies also indicate the previous owners’ intentions to erase these files and prevent future access by unauthorised individuals, and their failure to sufficiently do so. Moreover, these risks likely extend from the second-hand market to recycled memory chips – a practice encouraged under Directive 2012/19/EU on ‘waste electrical and electronic equipment’.
The implications for data security and data protection are substantial. End-users and companies alike could accidentally cause breaches of sensitive personal data of themselves or their customers. The protection of personal data is enshrined in Article 8 of the Charter of Fundamental Rights of the European Union, and the General Data Protection Regulation (GDPR) lays down rules and regulation for the protection of this fundamental right. For example, data processors could find themselves inadvertently in violation of Article 17 GDPR Right to Erasure (‘right to be forgotten’) despite their best intentions if they failed to erase a customer’s personal data – independent of whether that data was breached or not.
Seemingly minor design choices, the potential for major implications
The indication that people might fail to properly erase files from storage, despite their apparent intention to do so, is a strong sign of system failure. We know since more than twenty years that unintentional failure of users at a task “is often caused by the way in which [these] mechanisms are implemented, and users’ lack of knowledge”. In our case, these mechanisms are – for most users – the UI of Windows and macOS. When investigating these mechanisms, we found seemingly minor design choices that might facilitate unintentional data breaches. A few examples are shown below and are expanded upon in the full publication of our work.
A flaw in Apple’s Security Code AutoFill feature can affect a wide range of services, from online banking to instant messaging.
In June 2018, we reported a problem in the iOS 12 beta. In the previous post, we discussed the associated risks the problem creates for transaction authentication technology used in online banking and elsewhere. We described the underlying issue and that the risk will carry over to macOS Mojave. Since our initial reports, Apple has modified the Security Code AutoFill feature, but the problem is not yet solved.
In this blog post, we publish the results of our extended analysis and demonstrate that the changes made by Apple mitigated one symptom of the problem, but did not address the cause. Security Code AutoFill could leave Apple users in a vulnerable position after upgrading to iOS 12 and macOS Mojave, exposing them to risks beyond the scope of our initial reports.
We describe four example attacks that are intended to demonstrate the risks stemming from the flawed Security Code AutoFill, but intentionally omit the detail necessary to execute them against live systems. Note that supporting screenshots and videos in this article may identify companies whose services we’ve used to test our attacks. We do not infer that those companies’ systems would be affected any more or any less than their competitors.
Flaws in Security Code AutoFill
The Security Code AutoFill feature extracts short security codes (e.g., a one-time password or OTP) from an incoming SMS and allows the user to autofill that code into a web form, webpage, or app when authenticating. This feature is meant to provide convenience, as the user no longer needs to memorize and re-enter a code in order to authenticate. However, this convenience could create risks for the user.
A new feature for iPhones in iOS 12 – Security Code AutoFill – is supposed to improve the usability of Two Factor Authentication but could place users at risk of falling victim to online banking fraud.
Two Factor Authentication (2FA), which is often referred to as Two Step Verification, is an essential element for many security systems, especially those online and accessed remotely. In most cases, it provides extended security by checking if the user has access to a device. In SMS-based 2FA, for example, a user registers their phone number with an online service. When this service sees a login attempt for the corresponding user account, it sends a One Time Password (OTP), e.g. four to six digits, to the registered phone number. The legitimate user then receives this code and is able to quote it during the login process, but an impersonator won’t.
In a recent development by Apple, announced at its developer conference WWDC18, they are set to automate this last step to improve user experience with 2FA with a new feature that is set to be introduced to iOS in version 12. The Security Code AutoFill feature, currently available to developers in a beta version, will allow the mobile device to scan incoming SMS messages for such codes and suggest them at the top of the default keyboard.
Description of new iOS 12 Security Code AutoFill feature (source: Apple)
Currently, these SMS codes rely on the user actively switching apps and memorising the code, which can take a couple of seconds. Some users deploy alternative try strategies such as memorising the code from the preview banner and hastily typing it down. Apple’s new iOS feature will require only a single tap from the user. This will make the login process faster and less error prone, a significant improvement to the usability of 2FA. It could also translate into an increased uptake of 2FA among iPhone users.
Example of Security Code AutoFill feature in operation on iPhone (source: Apple)
If users synchronise SMS with their MacBook or iMac, the existing Text Message Forwarding feature will push codes from their iPhone and enable Security Code AutoFill in Safari.
Example of Security Code AutoFill feature synchronised with macOS Mojave (source: Apple)
Reducing friction in user interaction to improve technology uptake for new users, and increase the usability and satisfaction for existing users, is not a new concept. It has not only been discussed in academia at length but is also a common goal within industry, e.g. in banking. This is evident in how the financial and paymentindustry has encouraged contactless (Near Field Communication – NFC) payments, which makes transactions below a certain threshold much quicker than traditional Chip and PIN payments.
