The Android Security Rewards (ASR) program was created in 2015 to reward researchers who find and report security issues to help keep the Android ecosystem safe. Over the past 4 years, we have awarded over 1,800 reports, and paid out over four million dollars.
Today, we’re expanding the program and increasing reward amounts. We are introducing a top prize of $1 million for a full chain remote code execution exploit with persistence which compromises the Titan M secure element on Pixel devices. Additionally, we will be launching a specific program offering a 50% bonus for exploits found on specific developer preview versions of Android, meaning our top prize is now $1.5 million.
As mentioned in a previous blog post, in 2019 Gartner rated the Pixel 3 with Titan M as having the most “strong” ratings in the built-in security section out of all devices evaluated. This is why we’ve created a dedicated prize to reward researchers for exploits found to circumvent the secure elements protections.
In addition to exploits involving Pixel Titan M, we have added other categories of exploits to the rewards program, such as those involving data exfiltration and lockscreen bypass. These rewards go up to $500,000 depending on the exploit category. For full details, please refer to the Android Security Rewards Program Rules page.
Now that we’ve covered some of what’s new, let’s take a look back at some milestones from this year. Here are some highlights from 2019:
The highest reward paid out to a member of the research community was for a report from Guang Gong (@oldfresher) of Alpha Lab, Qihoo 360 Technology Co. Ltd. This report detailed the first reported 1-click remote code execution exploit chain on the Pixel 3 device. Guang Gong was awarded $161,337 from the Android Security Rewards program and $40,000 by Chrome Rewards program for a total of $201,337. The $201,337 combined reward is also the highest reward for a single exploit chain across all Google VRP programs. The Chrome vulnerabilities leveraged in this report were fixed in Chrome 77.0.3865.75 and released in September, protecting users against this exploit chain.
We’d like to thank all of our researchers for contributing to the security of the Android ecosystem. If you’re interested in becoming a researcher, check out our Bughunter University for information on how to get started.
Starting today November 21, 2019 the new rewards take effect. Any reports that were submitted before November 21, 2019 will be rewarded based on the previously existing rewards table.
Happy bug hunting!
Memory safety errors, like use-after-frees and out-of-bounds reads/writes, are a leading source of vulnerabilities in C/C++ applications. Despite investments in preventing and detecting these errors in Chrome, over 60% of high severity vulnerabilities in Chrome are memory safety errors. Some memory safety errors don’t lead to security vulnerabilities but simply cause crashes and instability.
Chrome uses state-of-the-art techniques to prevent these errors, including:
Chrome also makes use of sandboxing and exploit mitigations to complicate exploitation of memory errors that go undetected by the methods above.
AddressSanitizer is a compiler instrumentation that finds memory errors occurring on the heap, stack, or in globals. ASan is highly effective and one of the lowest overhead instrumentations available that detects the errors that it does; however, it still incurs an average 2-3x performance and memory overhead. This makes it suitable for use with unit tests or fuzzing, but not deployment to end users. Chrome used to deploy SyzyASAN instrumented binaries to detect memory errors. SyzyASAN had a similar overhead so it was only deployed to a small subset of users on the canary channel. It was discontinued after the Windows toolchain switched to LLVM.
GWP-ASan, also known by its recursive backronym, GWP-ASan Will Provide Allocation Sanity, is a sampling allocation tool designed to detect heap memory errors occurring in production with negligible overhead. Because of its negligible overhead we can deploy GWP-ASan to the entire Chrome user base to find memory errors happening in the real world that are not caught by fuzzing or testing with ASan. Unlike ASan, GWP-ASan can not find memory errors on the stack or in globals.
GWP-ASan is currently enabled for all Windows and macOS users for allocations made using malloc() and PartitionAlloc. It is only enabled for a small fraction of allocations and processes to reduce performance and memory overhead to a negligible amount. At the time of writing it has found over sixty bugs (many are still restricted view). About 90% of the issues GWP-ASan has found are use-after-frees. The remaining are out-of-bounds reads and writes.
To learn more, check out our full write up on GWP-ASan here.
CONFIG_SHADOW_CALL_STACK=y # CONFIG_SHADOW_CALL_STACK_VMAP is not set # CONFIG_DEBUG_STACK_USAGE is not set
By default, shadow stacks are not virtually allocated to minimize memory overhead, but CONFIG_SHADOW_CALL_STACK_VMAP can be enabled for better stack exhaustion protection. With CONFIG_DEBUG_STACK_USAGE, the kernel will also print out shadow stack usage in addition to normal stack usage which can be helpful when debugging issues.
The Chrome Security team values having multiple lines of defense. Web browsers are complex, and malicious web pages may try to find and exploit browser bugs to steal data. Additional lines of defense, like sandboxes, make it harder for attackers to access your computer, even if bugs in the browser are exploited. With Site Isolation, Chrome has gained a new line of defense that helps protect your accounts on the Web as well.
Site Isolation ensures that pages from different sites end up in different sandboxed processes in the browser. Chrome can thus limit the entire process to accessing data from only one site, making it harder for an attacker to steal cross-site data. We started isolating all sites for desktop users back in Chrome 67, and now we’re excited to enable it on Android for sites that users log into in Chrome 77. We've also strengthened Site Isolation on desktop to help defend against even fully compromised processes.
Site Isolation helps defend against two types of threats. First, attackers may try to use advanced "side channel" attacks to leak sensitive data from a process through unexpected means. For example, Spectre attacks take advantage of CPU performance features to access data that should be off limits. With Site Isolation, it is harder for the attacker to get cross-site data into their process in the first place.
Second, even more powerful attackers may discover security bugs in the browser, allowing them to completely hijack the sandboxed process. On desktop platforms, Site Isolation can now catch these misbehaving processes and limit their access to cross-site data. We're working to bring this level of hijacked process protection to Android in the future as well.
Thanks to this extra line of defense, Chrome can now help keep your web accounts even more secure. We are still making improvements to get the full benefits of Site Isolation, but this change gives Chrome a solid foundation for protecting your data.
If you’d like to learn more, check out our technical write up on the Chromium blog.
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